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springboot教程（一）

發布時間：2024/9/16 编程问答 30 豆豆

生活随笔收集整理的這篇文章主要介紹了 springboot教程（一）小編覺得挺不錯的,現在分享給大家,幫大家做個參考.

擼了今年阿里、頭條和美團的面試，我有一個重要發現.......>>>

使用jdk:1.8、maven:3.3.3

spring獲取Bean的方式

pom.xml文件內容：

配置類MyConfig.java：

package com.edu.spring;import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration;/*** 配置類*/@Configuration public class MyConfig {// 配置一個bean@Beanpublic MyBean createMyBean(){return new MyBean();}}

MyBean.java

package com.edu.spring;public class MyBean { }

主函數：App.java

package com.edu.spring;import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class App {public static void main(String[] args) {AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MyConfig.class);// 從容器中獲取bean---從類型獲取System.out.println(context.getBean(MyBean.class));// 從容器中獲取bean---從名字獲取，默認名字是方法名System.out.println(context.getBean("createMyBean"));context.close();} }

輸出結果如下：

com.edu.spring.MyBean@1445d7f
com.edu.spring.MyBean@1445d7f

如果需要指定bean名字，需要修改MyConfig.java：

@Configuration public class MyConfig {// 配置一個bean@Bean(name = "myBean")public MyBean createMyBean(){return new MyBean();}}

然后在App.java指定Bean的名字：這樣就無法根據方法名獲取Bean了。

public class App {public static void main(String[] args) {AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MyConfig.class);// 從容器中獲取bean---從類型獲取System.out.println(context.getBean(MyBean.class));// 從容器中獲取bean---從名字獲取，默認名字是方法名// System.out.println(context.getBean("createMyBean"));// 從容器中獲取bean---從指定名字獲取System.out.println(context.getBean("myBean"));context.close();} }

Bean默認是單例

我們可以看到，Bean是單例的，兩次打印出的對象是一樣的。

如果我們想修改Bean的單例為多例，修改MyConfig.java如下（添加scope(prototype)）:

@Configuration public class MyConfig {// 配置一個bean@Bean(name = "myBean")@Scope("prototype")public MyBean createMyBean(){return new MyBean();}}

打印如下：

com.edu.spring.MyBean@10b48321
com.edu.spring.MyBean@6b67034

FactoryBean

新建方法JeepFactoryBean.java

package com.edu.spring;import org.springframework.beans.factory.FactoryBean;public class JeepFactoryBean implements FactoryBean<Jeep> {/*** 創建的實例對象* @return* @throws Exception*/@Overridepublic Jeep getObject() throws Exception {return new Jeep();}/**** @return*/@Overridepublic Class<?> getObjectType() {return Jeep.class;}@Overridepublic boolean isSingleton() {return true;} }

在MyConfig.java中添加配置：

@Beanpublic JeepFactoryBean createJeepFactoryBean(){return new JeepFactoryBean();}

可以在App.java中得到Jeep.class。

System.out.println(context.getBean(Jeep.class)); System.out.println(context.getBean("createJeepFactoryBean"));

如果要獲取JeepFactoryBean本身，而不是工廠生產出的類，可以通過下面的兩種方式獲取：

System.out.println(context.getBean(JeepFactoryBean.class)); System.out.println(context.getBean("&createJeepFactoryBean"));

目前有兩種方式進行Bean的裝配，一種是使用FactoryBean，一種是原始方式

使用第三種裝配

新建CarFactory.java

public class CarFactory {public Car create(){return new Car();} }

新建Car.java

配置MyConfig.java

@Beanpublic Car createJeep(CarFactory carFactory){return carFactory.create();}@Beanpublic CarFactory createCarFactory(){return new CarFactory();}

獲取對象：

System.out.println(context.getBean(Car.class));

因為，在Bean的裝配過程中，需要參數的時候，spring會默認從當前容器中獲取到對應的參數，然后注入。

Bean初始化，在Bean初始化時，進行一些操作。

方式一：

創建Cat.java

package com.edu.spring;import org.springframework.beans.factory.DisposableBean; import org.springframework.beans.factory.InitializingBean;public class Cat implements InitializingBean, DisposableBean {@Overridepublic void afterPropertiesSet() throws Exception {System.out.println("====afterPropertiesSet====");}@Overridepublic void destroy() throws Exception {System.out.println("====destroy====");} }

配置MyConfig.java

@Beanpublic Cat createCat(){return new Cat();}

獲得cat

System.out.println(context.getBean(Cat.class));

控制臺打印：

====afterPropertiesSet==== com.edu.spring.MyBean@7fe8ea47 com.edu.spring.MyBean@226a82c4 com.edu.spring.JeepFactoryBean@731f8236 com.edu.spring.JeepFactoryBean@731f8236 com.edu.spring.Jeep@255b53dc com.edu.spring.Jeep@255b53dc com.edu.spring.Car@1dd92fe2 com.edu.spring.Cat@6b53e23f ====destroy====

方法二：

創建Dog.java

package com.edu.spring;public class Dog {public void myInit(){System.out.println("init=====");}public void myDestory(){System.out.println("destory===");}}

在配置MyConfig.java時指定初始化時執行和銷毀時執行的方法

@Bean(initMethod = "myInit", destroyMethod = "myDestory")public Dog createDog(){return new Dog();}

方式三：

新建Fish.java

package com.edu.spring;import javax.annotation.PostConstruct; import javax.annotation.PreDestroy;public class Fish {@PostConstructpublic void initial(){System.out.println("fish init");}@PreDestroypublic void close(){System.out.println("fish close");}}

配置MyConfig.java

@Beanpublic Fish createFish(){return new Fish();}

Bean裝配

新建User.java

package com.edu.spring;import org.springframework.stereotype.Component;@Component public class User { }

修改App.java，將User.class添加到容器

AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MyConfig.class, User.class); System.out.println(context.getBean(User.class));

但是使用@Component，則無法使用@Bean(initMethod = "myInit", destroyMethod = "myDestory")設置初始化和銷毀的方法

此外，默認的名字是類名。可以指定名字：

@Component("myUser")

如果此時同樣在MyConfig.java中，配置一個Bean，

@Beanpublic User createUser(){return new User();}

則會報錯：

Exception in thread "main" org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'com.edu.spring.User' available: expected single matching bean but found 2: myUser,createUserat org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveNamedBean(DefaultListableBeanFactory.java:1034)at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:340)at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:335)at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1101)at com.edu.spring.App.main(App.java:24)

也就是說通過類型獲取User時找到了兩個一個是myUser一個是createUser。如果我們通過名字來獲取就沒有問題了。

System.out.println(context.getBean("myUser"));

如果想獲取，User類型的所有對象，可以使用getBeansOfType方法。

除了使用Component，還可以使用Repository來裝配類，一般用在數據訪問層，而Component一般用于沒有明確角色的時候。

新建UserDao.java

@Repository public class UserDao { }

添加到AnnotationConfigApplicationContext中

AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MyConfig.class, User.class, UserDao.class); System.out.println(context.getBean(UserDao.class));

還可以使用Service來裝配，一般用在業務邏輯層

新建UserService.java，

// 業務邏輯層 @Service public class UserService { }

添加到AnnotationConfigApplicationContext：

AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MyConfig.class, User.class, UserDao.class, UserService.class); System.out.println(context.getBean(UserService.class));

使用Controller來裝配，一般用于展示層，

package com.edu.spring;import org.springframework.stereotype.Controller;// 用在展示層 @Controller public class UserController { }

依賴注入

在User中，依賴UserService.java

User.java

package com.edu.spring;import org.springframework.stereotype.Component;@Component("myUser") public class User {private UserService userService;public UserService getUserService() {return userService;}public void setUserService(UserService userService) {this.userService = userService;}@Overridepublic String toString() {return "User{" +"userService=" + userService +'}';} }

在App.java中調用show方法

AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(MyConfig.class, User.class, UserDao.class, UserService.class, UserController.class); User user = context.getBean("myUser", User.class); user.show(); context.close();

輸出打印：

null

說明UserService沒有注入進去，使用@AutoWired修飾UserService，便可以注入進去了，同時也不需要set get方法了。

package com.edu.spring;import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component;@Component("myUser") public class User {@Autowiredprivate UserService userService;@Overridepublic String toString() {return "UserService{" +"userDao=" + userDao +'}';}}

打印輸出：

User{userService=UserService{userDao=com.edu.spring.UserDao@3bbc39f8}}

說明成功注入進去了。

如果繼續在MyConfig.java中裝配一個Bean：

@Beanpublic UserDao createUserDao(){return new UserDao();}

那么這時，就會有兩個UserDao存在，就不知道用哪個對象，出現報錯：

Exception in thread "main" org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'com.edu.spring.UserDao' available: expected single matching bean but found 2: userDao,createUserDaoat org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveNamedBean(DefaultListableBeanFactory.java:1034)at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:340)at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:335)at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1101)at com.edu.spring.App.main(App.java:26)

這時可以用兩個方法解決問題。

方法一：使用Qualifier注釋

@Service public class UserService {@Autowired@Qualifier("createUserDao")private UserDao userDao;@Overridepublic String toString() {return "UserService{" +"userDao=" + userDao +'}';} }

這樣就知道用哪一個對象了。（注意要將其他所有用到UserDao的地方，都需要使用Qualifier指明到底用哪一個userdao）

方法二：使用Primary注釋Bean

在MyConfig.java中：

@Bean@Primarypublic UserDao createUserDao(){return new UserDao();}

Primary用于有多個對象存在時，首先尋找標有Primary的對象，進行注入。

如果要注入其他類，比如Car.java，需要使用Resource注釋來注入。

package com.edu.spring;import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component;import javax.annotation.Resource;@Component("myUser") public class User {@Autowiredprivate UserService userService;// 使用JSR 250的注解@Resourceprivate Car car;@Overridepublic String toString() {return "User{" +"userService=" + userService +", car=" + car +'}';} }

輸出：User{userService=UserService{userDao=com.edu.spring.UserDao@1b083826}, car=com.edu.spring.Car@55a1c291}

說明Car.java 也注入進來了。

此外還可以使用 JSR 330 的注解方式進行注入，但是這種方式需要添加依賴：

<dependency><groupId>javax.inject</groupId><artifactId>javax.inject</artifactId><version>1</version></dependency>

嘗試將Cat.java注入進去User。使用Inject注釋。

package com.edu.spring;import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Component;import javax.annotation.Resource; import javax.inject.Inject;@Component("myUser") public class User {// Spring提供的注解@Autowiredprivate UserService userService;// 使用JSR-250的注解@Resourceprivate Car car;// 使用JSR-330的注解@Injectprivate Cat cat;@Overridepublic String toString() {return "User{" +"userService=" + userService +", car=" + car +", cat=" + cat +'}';} }

控制臺顯示輸出：信息: JSR-330 'javax.inject.Inject' annotation found and supported for autowiring 說明JSR330 已經起作用了。

User{userService=UserService{userDao=com.edu.spring.UserDao@55ca8de8}, car=com.edu.spring.Car@5d740a0f, cat=com.edu.spring.Cat@214b199c}
說明cat也成功注入進去了。

我們發現AnnotationConfigApplicationContext很麻煩，每次都需要手動去添加新的類。

我們可以使用包掃描的方式進行類裝載，更加方便。

package com.edu.spring;import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class AnnotationClient {public static void main(String[] args) {AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext("com.edu.spring");System.out.println(context.getBean(Jeep.class));System.out.println(context.getBean("createJeepFactoryBean"));System.out.println(context.getBean(Car.class));System.out.println(context.getBean(Cat.class));System.out.println(context.getBean(Dog.class));System.out.println(context.getBean(Fish.class));System.out.println(context.getBean("myUser"));context.close();} }

如果我們想排除某一些類，這些類不想被掃描到。方法如下：

新建AnnotationScan.java

package com.edu.spring;import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration;@ComponentScan("com.edu.spring") @Configuration public class AnnotationScan { }

新建AnnotationClient2.java

package com.edu.spring;import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class AnnotationClient2 {public static void main(String[] args) {AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AnnotationScan.class);context.close();} }

這種方法同樣可以達到掃描包的效果。如果我們想排除Dog類，需要將MyConfig.java中的配置Dog的地方刪除，新建DogConfig.java

package com.edu.spring;import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration;@Configuration public class DogConfig {@Bean(initMethod = "myInit", destroyMethod = "myDestory")public Dog createDog(){return new Dog();}}

修改AnnotationScan.java

package com.edu.spring;import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.FilterType;@ComponentScan(basePackages = "com.edu.spring", excludeFilters = @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = DogConfig.class)) @Configuration public class AnnotationScan { }

這樣就將Dog類排除了，然后執行AnnotationClient2.java 就會報錯：

Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.edu.spring.Dog' availableat org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:348)at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:335)at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1101)at com.edu.spring.AnnotationClient2.main(AnnotationClient2.java:13)

說明Dog已經排除成功了。同樣可以排除UserController.java

因為UserController上有注釋，可以直接排除。

package com.edu.spring;import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.FilterType;@ComponentScan(basePackages = "com.edu.spring", excludeFilters = @ComponentScan.Filter(type = FilterType.ASSIGNABLE_TYPE, classes = {DogConfig.class, UserController.class})) @Configuration public class AnnotationScan { }

第二課

Spring有兩個核心接口：BeanFactory和ApplicationContext，其中ApplicationContext是BeanFactory的子接口。他們都可代表Spring容器，Spring容器是生成Bean實例的工廠，并且管理容器中的Bean。

BeanFactory負責配置、創建、管理Bean，他有一個子接口：ApplicationContext，因此也稱之為Spring上下文。Spring容器負責管理Bean與Bean之間的依賴關系。

BeanFactory接口包含以下幾個基本方法：

Boolean containBean(String name):判斷Spring容器是否包含id為name的Bean實例。
<T> getBean(Class<T> requiredTypr):獲取Spring容器中屬于requiredType類型的唯一的Bean實例。
Object getBean(String name)：返回Sprin容器中id為name的Bean實例。
<T> T getBean(String name,Class requiredType)：返回容器中id為name,并且類型為requiredType的Bean
Class <?> getType(String name)：返回容器中指定Bean實例的類型。?

?調用者只需使用getBean()方法即可獲得指定Bean的引用，無須關心Bean的實例化過程。即Bean實例的創建過程完全透明。

讓Bean獲取Spring容器

????在Spring中我們可以使用Spring容器中getBean()方法來獲取Spring容器中的Bean實例。在這樣的訪問模式下，程序中總是持有Spring容器的引用。但是在實際的應用中，Spring容器通常是采用聲明式方式配置產生：即開發者只要在web.xml文件中配置一個Listener，該Listener將會負責初始化Spring容器。在這種情況下，容器中Bean處于容器管理下，無須主動訪問容器，只需要接受容器的注入管理即可。同時Bean實例的依賴關系通常也是由容器自動注入，無須Bean實例主動請求。

如何注入ApplicationContext?

新建myConfig.java

package com.edu.spring;import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration;@Configuration public class MyConfig {@Beanpublic User createUser(){return new User();}}

新建User.java

新建App.java

package com.edu.spring;import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class App {public static void main(String[] args) {AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext("com.edu.spring");System.out.println(context.getBean(User.class));System.out.println(context.getBean("createUser"));context.getBean(User.class).show();context.close();} }

方法一：

在Use.java中使用AutoWired成功注入ApplicationContext。也可以使用JSR 250 和JSR330 方式注入

輸出如下：

com.edu.spring.User@6ee12bac com.edu.spring.User@6ee12bac user:class org.springframework.context.annotation.AnnotationConfigApplicationContext

方法二：

新建Book.java

package com.edu.spring;import org.springframework.beans.BeansException; import org.springframework.context.ApplicationContext; import org.springframework.context.ApplicationContextAware; import org.springframework.stereotype.Component;@Component public class Book implements ApplicationContextAware {private ApplicationContext applicationContext;@Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {this.applicationContext = applicationContext;}public void show(){System.out.println("book:" + applicationContext.getClass());}}

方法三：

新鍵Bank.java

package com.edu.spring;import org.springframework.context.ApplicationContext; import org.springframework.stereotype.Component;@Component public class Bank {private ApplicationContext applicationContext;public Bank (ApplicationContext applicationContext){this.applicationContext = applicationContext;}public void show(){System.out.println("bank:" + applicationContext.getClass());}}

這種方法同樣可以注入ApplicationContext。但是這個方法，構造函數只能有一個，如果有多個的話，就必須有一個無參的構造函數，此時，spring會調用無參的構造函數。構造函數的參數，必須都要在Spring容器中。

BeanPostProcessor

BeanPostProcessor會在每個bean初始化的時候，調用一次

新建EchoBeanPostProcessor.java

package com.edu.spring;import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.lang.Nullable; import org.springframework.stereotype.Component;/*** BeanPostProcessor會在每個bean初始化的時候，調用一次*/ @Component public class EchoBeanPostProcessor implements BeanPostProcessor {// 在bean依賴裝配（屬性設置完）完成之后觸發@Nullable@Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {System.out.println("====postProcessBeforeInitialization======" + bean.getClass());return bean;}// 在bean init方法執行之后觸發@Nullable@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {System.out.println("====postProcessAfterInitialization======" + bean.getClass());return bean;} }

打印輸出如下：

====postProcessBeforeInitialization======class org.springframework.context.event.EventListenerMethodProcessor ====postProcessAfterInitialization======class org.springframework.context.event.EventListenerMethodProcessor ====postProcessBeforeInitialization======class org.springframework.context.event.DefaultEventListenerFactory ====postProcessAfterInitialization======class org.springframework.context.event.DefaultEventListenerFactory ====postProcessBeforeInitialization======class com.edu.spring.Bank ====postProcessAfterInitialization======class com.edu.spring.Bank ====postProcessBeforeInitialization======class com.edu.spring.Book ====postProcessAfterInitialization======class com.edu.spring.Book ====postProcessBeforeInitialization======class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$3a1c64d1 ====postProcessAfterInitialization======class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$3a1c64d1 ====postProcessBeforeInitialization======class com.edu.spring.User ====postProcessAfterInitialization======class com.edu.spring.User com.edu.spring.User@482cd91f com.edu.spring.User@482cd91f user:class org.springframework.context.annotation.AnnotationConfigApplicationContext book:class org.springframework.context.annotation.AnnotationConfigApplicationContext bank:class org.springframework.context.annotation.AnnotationConfigApplicationContext

在每個bean初始化之前和之后執行的方法。????

如果我們給User添加一個初始化方法init

user.java

在MyConfig.java中指定初始化方法：

package com.edu.spring;import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration;@Configuration public class MyConfig {@Bean(initMethod = "init")public User createUser(){return new User();}}

則輸出結果如下：

====postProcessBeforeInitialization======class org.springframework.context.event.EventListenerMethodProcessor ====postProcessAfterInitialization======class org.springframework.context.event.EventListenerMethodProcessor ====postProcessBeforeInitialization======class org.springframework.context.event.DefaultEventListenerFactory ====postProcessAfterInitialization======class org.springframework.context.event.DefaultEventListenerFactory ====postProcessBeforeInitialization======class com.edu.spring.Bank ====postProcessAfterInitialization======class com.edu.spring.Bank ====postProcessBeforeInitialization======class com.edu.spring.Book ====postProcessAfterInitialization======class com.edu.spring.Book ====postProcessBeforeInitialization======class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$3a1c64d1 ====postProcessAfterInitialization======class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$3a1c64d1 ====postProcessBeforeInitialization======class com.edu.spring.User user init ====postProcessAfterInitialization======class com.edu.spring.User com.edu.spring.User@482cd91f com.edu.spring.User@482cd91f user:class org.springframework.context.annotation.AnnotationConfigApplicationContext book:class org.springframework.context.annotation.AnnotationConfigApplicationContext bank:class org.springframework.context.annotation.AnnotationConfigApplicationContext

說明postProcessBeforeInitialization方法是在bean init方法之前執行，postProcessAfterInitialization方法是在bean init方法之后執行。

修改User.java

package com.edu.spring;import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.ApplicationContext;public class User {private ApplicationContext applicationContext;public void init(){System.out.println("user init");}public void show(){System.out.println("user:" + applicationContext.getClass());}@Autowiredpublic void setApplicationContext(ApplicationContext applicationContext) {System.out.println("applicationContext set");this.applicationContext = applicationContext;} }

Autowired既可以用在變量上，也可以用在方法上。

輸出結果如下：

====postProcessBeforeInitialization======class org.springframework.context.event.EventListenerMethodProcessor ====postProcessAfterInitialization======class org.springframework.context.event.EventListenerMethodProcessor ====postProcessBeforeInitialization======class org.springframework.context.event.DefaultEventListenerFactory ====postProcessAfterInitialization======class org.springframework.context.event.DefaultEventListenerFactory ====postProcessBeforeInitialization======class com.edu.spring.Bank ====postProcessAfterInitialization======class com.edu.spring.Bank ====postProcessBeforeInitialization======class com.edu.spring.Book ====postProcessAfterInitialization======class com.edu.spring.Book ====postProcessBeforeInitialization======class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$50df4f2b ====postProcessAfterInitialization======class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$50df4f2b applicationContext set ====postProcessBeforeInitialization======class com.edu.spring.User user init ====postProcessAfterInitialization======class com.edu.spring.User com.edu.spring.User@5b0abc94 com.edu.spring.User@5b0abc94 user:class org.springframework.context.annotation.AnnotationConfigApplicationContext book:class org.springframework.context.annotation.AnnotationConfigApplicationContext bank:class org.springframework.context.annotation.AnnotationConfigApplicationContext

說明依賴都裝配完成之后出發postProcessBeforeInitialization

代理對象

新建LogUser.java

package com.edu.spring;public class LogUser extends User {@Overridepublic void show() {System.out.println("log start ...");super.show();System.out.println("log end ...");} }

修改Use.java

public void show(){System.out.println("user:" + applicationContext);}

修改EchoBeanPostProcessor.java

public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {System.out.println("====postProcessBeforeInitialization======" + bean.getClass());if(bean instanceof User){return new LogUser();}return bean;}

輸出結果如下：

====postProcessBeforeInitialization======class org.springframework.context.event.EventListenerMethodProcessor ====postProcessAfterInitialization======class org.springframework.context.event.EventListenerMethodProcessor ====postProcessBeforeInitialization======class org.springframework.context.event.DefaultEventListenerFactory ====postProcessAfterInitialization======class org.springframework.context.event.DefaultEventListenerFactory ====postProcessBeforeInitialization======class com.edu.spring.Bank ====postProcessAfterInitialization======class com.edu.spring.Bank ====postProcessBeforeInitialization======class com.edu.spring.Book ====postProcessAfterInitialization======class com.edu.spring.Book ====postProcessBeforeInitialization======class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$50df4f2b ====postProcessAfterInitialization======class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$50df4f2b applicationContext set ====postProcessBeforeInitialization======class com.edu.spring.User user init ====postProcessAfterInitialization======class com.edu.spring.LogUser com.edu.spring.LogUser@75c072cb com.edu.spring.LogUser@75c072cb log start ... user:null log end ... book:class org.springframework.context.annotation.AnnotationConfigApplicationContext bank:class org.springframework.context.annotation.AnnotationConfigApplicationContext

可以對指定的Bean做一些處理，比如返回對象的代理對象。

spring擴展二

目前我們知道BeanPostProcessor是在某個bean初始化的時候，進行回調的，我們可以控制bean的初始化和其他的操作。如果我們想要對某個容器進行初始化回調，如何做？spring同樣留了接口， BeanFactoryPostProcessor，是在spring容器初始化之后進行的

新建App.java

新建MyBeanFactoryPostProcessor.java

package com.edu.spring;import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanFactoryPostProcessor; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.stereotype.Component;/*** BeanFactoryPostProcessor在spring容器的初始化之后出發，而且只會觸發一次* 觸發的時機比BeanPostProcessor早*/ @Component public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor {@Overridepublic void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {System.out.println("============" + configurableListableBeanFactory.getBeanDefinitionCount());} }

運行App.java 輸出結果如下：

============7

說明即使我們什么都不做，spring容器還是有很多個bean的。

新建User.java

public class User {public void init(){System.out.println("user init");} }

新建MyConfig.java

package com.edu.spring;import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration;@Configuration public class MyConfig {@Bean(initMethod = "init")public User createUser(){return new User();}@Beanpublic User createUser2(){return new User();}}

運行App.java，輸出結果如下：

============10 user init

新建MyBeanPostProcessor.java，對比BeanPostProcessor和BeanFactoryPostProcessor執行順序是什么

package com.edu.spring;import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.stereotype.Component;@Component public class MyBeanPostProcessor implements BeanPostProcessor {@Overridepublic Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {System.out.println("====postProcessBeforeInitialization=====" + bean.getClass());return bean;}@Overridepublic Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {System.out.println("====postProcessAfterInitialization=====" + bean.getClass());return bean;} }

運行輸出結果：

============11 四月 22, 2019 3:47:16 下午 org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor <init> 信息: JSR-330 'javax.inject.Inject' annotation found and supported for autowiring ====postProcessBeforeInitialization=====class org.springframework.context.event.EventListenerMethodProcessor ====postProcessAfterInitialization=====class org.springframework.context.event.EventListenerMethodProcessor ====postProcessBeforeInitialization=====class org.springframework.context.event.DefaultEventListenerFactory ====postProcessAfterInitialization=====class org.springframework.context.event.DefaultEventListenerFactory ====postProcessBeforeInitialization=====class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$a601222d ====postProcessAfterInitialization=====class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$a601222d ====postProcessBeforeInitialization=====class com.edu.spring.User user init ====postProcessAfterInitialization=====class com.edu.spring.User ====postProcessBeforeInitialization=====class com.edu.spring.User ====postProcessAfterInitialization=====class com.edu.spring.User

說明BeanFactoryPostProcessor最先執行，但只會執行一次，因為容器執行完成一次。

BeanDefinitionRegistry

我們使用Component注釋來注冊一個bean，但這是靜態的注冊，我們可以通過BeanDefinitionRegistry來動態注冊一個Bean。

新建一個要注入的類Person.java

package com.edu.spring;public class Person {private String name;@Overridepublic String toString() {return "Person{" +"name='" + name + '\'' +'}';}public String getName() {return name;}public void setName(String name) {this.name = name;} }

新建MyBeanDefinitionRegistryPostProcessor.java，注入十個Person類，并給他們的屬性賦值。

package com.edu.spring;import org.springframework.beans.BeansException; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.beans.factory.support.BeanDefinitionBuilder; import org.springframework.beans.factory.support.BeanDefinitionRegistry; import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor; import org.springframework.stereotype.Component;/*** BeanDefinitionRegistryPostProcessor可以拿到BeanDefinitionRegistry，ConfigurableListableBeanFactory兩個對象* BeanDefinitionRegistry可以動態注入bean*/ @Component public class MyBeanDefinitionRegistryPostProcessor implements BeanDefinitionRegistryPostProcessor {@Overridepublic void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry beanDefinitionRegistry) throws BeansException {for( int i = 0; i < 10; i++){BeanDefinitionBuilder beanDefinitionBuilder = BeanDefinitionBuilder.rootBeanDefinition(Person.class);// 往person內注入屬性,可以注入引用beanDefinitionBuilder.addPropertyValue("name", "admin" + i);beanDefinitionRegistry.registerBeanDefinition("person" + i, beanDefinitionBuilder.getBeanDefinition());}}@Overridepublic void postProcessBeanFactory(ConfigurableListableBeanFactory configurableListableBeanFactory) throws BeansException {} }

修改App.java

package com.edu.spring;import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class App {public static void main(String[] args) {AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext("com.edu.spring");context.getBeansOfType(Person.class).values().forEach(person -> {System.out.println(person);});context.close();} }

輸出結果：

============22 四月 22, 2019 4:38:56 下午 org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor <init> 信息: JSR-330 'javax.inject.Inject' annotation found and supported for autowiring ====postProcessBeforeInitialization=====class org.springframework.context.event.EventListenerMethodProcessor ====postProcessAfterInitialization=====class org.springframework.context.event.EventListenerMethodProcessor ====postProcessBeforeInitialization=====class org.springframework.context.event.DefaultEventListenerFactory ====postProcessAfterInitialization=====class org.springframework.context.event.DefaultEventListenerFactory ====postProcessBeforeInitialization=====class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$bc5fcd78 ====postProcessAfterInitialization=====class com.edu.spring.MyConfig$$EnhancerBySpringCGLIB$$bc5fcd78 ====postProcessBeforeInitialization=====class com.edu.spring.User user init ====postProcessAfterInitialization=====class com.edu.spring.User ====postProcessBeforeInitialization=====class com.edu.spring.User ====postProcessAfterInitialization=====class com.edu.spring.User ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person ====postProcessBeforeInitialization=====class com.edu.spring.Person ====postProcessAfterInitialization=====class com.edu.spring.Person Person{name='admin0'} Person{name='admin1'} Person{name='admin2'} Person{name='admin3'} Person{name='admin4'} Person{name='admin5'} Person{name='admin6'} Person{name='admin7'} Person{name='admin8'} Person{name='admin9'}

說明Person自動注入進去了。

除了這個方法，也可以使用

AnnotationConfigApplicationContext context.registerBeanDefinition(beanName, beanDefinition);

springboot-1

新建pom.xml

新建App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.Bean;@SpringBootApplication public class App {@Beanpublic Runnable createRunable(){return () -> {System.out.println("spring boot is running");};}public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);context.getBean(Runnable.class).run();} }

運行App.java 可以得到輸出結果如下：

. ____ _ __ _ _/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \ ( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/ ___)| |_)| | | | | || (_| | ) ) ) )' |____| .__|_| |_|_| |_\__, | / / / /=========|_|==============|___/=/_/_/_/:: Spring Boot :: (v2.1.4.RELEASE)2019-04-22 22:52:03.868 INFO 11372 --- [ main] com.edu.spring.App : Starting App on duandingyangdeMacBook-Pro.local with PID 11372 (/Users/duandingyang/git-project/springcourse/target/classes started by duandingyang in /Users/duandingyang/git-project/springcourse) 2019-04-22 22:52:03.876 INFO 11372 --- [ main] com.edu.spring.App : No active profile set, falling back to default profiles: default 2019-04-22 22:52:04.651 INFO 11372 --- [ main] com.edu.spring.App : Started App in 1.432 seconds (JVM running for 2.166) spring boot is running

這是一個最簡單的SpringBoot應用。

跟之前的spring使用方法差不多，只是main的入口變了。

在pom.xml文件中，如果我們不想使用parent依賴，應該怎么做？

新的pom.xml如下

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>cn.ac.iie</groupId><artifactId>spring-course</artifactId><version>1.0-SNAPSHOT</version><packaging>jar</packaging><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target></properties><dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>2.1.4.RELEASE</version><scope>import</scope><type>pom</type></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency></dependencies> </project>

在App.java中，點擊查看@SpringBootApplication注釋，有三個重要的注釋，分別是@SpringBootConfiguration @EnableAutoConfiguration @ComponentScan

目前的情況，我們可以直接使用@ComponentScan注釋就行

App.java如下：

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan;@ComponentScan public class App {@Beanpublic Runnable createRunable(){return () -> {System.out.println("spring boot is running");};}public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);context.getBean(Runnable.class).run();} }

運行結果跟之前是一樣的。

其實SpringApplication.run(App.class, args)中App.class一般就是入口，也就是配置類，里面可以配置各種Bean。

刪掉@ComponentScan 修改入口配置

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.ComponentScan;public class App {@Beanpublic Runnable createRunable(){return () -> {System.out.println("spring boot is running");};}public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App2.class, args);context.getBean(Runnable.class).run();} }

新建App2.java

package com.edu.spring;import org.springframework.context.annotation.ComponentScan;@ComponentScan public class App2 {}

這樣輸出結果如下：

Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'java.lang.Runnable' availableat org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:343)at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBean(DefaultListableBeanFactory.java:335)at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1123)at com.edu.spring.App.main(App.java:21)

因為找不到bean，如果將App.java中的生命bean 的代碼剪切到App2.java中，那么程序正常運行。

也可以通過這個方式加載配置類：

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.context.ConfigurableApplicationContext;import java.util.HashSet; import java.util.Set;public class App {public static void main(String[] args) {SpringApplication application = new SpringApplication(App2.class);ConfigurableApplicationContext context = application.run(args);context.getBean(Runnable.class).run();}}

新建MyConfig.java

package com.edu.spring;import org.springframework.boot.SpringBootConfiguration; import org.springframework.context.annotation.Bean;import java.util.ArrayList; import java.util.List;@SpringBootConfiguration public class MyConfig {@Beanpublic List<String> createList(){ArrayList arrayList = new ArrayList();arrayList.add("a");return arrayList;}}

使用SpringBootConfiguration同樣可以裝配Bean

App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.context.ConfigurableApplicationContext;import java.util.List;public class App {public static void main(String[] args) {SpringApplication application = new SpringApplication(App2.class);ConfigurableApplicationContext context = application.run(args);context.getBean(Runnable.class).run();System.out.println(context.getBean(List.class));}}

Springboot配置文件

springboot默認的配置文件是application.properties.

新建application.properties，內容如下：

local.ip=192.168.1.1 local.port=8080name=springboot app.name=this is ${name}

方法一使用context.getEnvironment().getProperty("local.ip")

新建App.java,

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.SpringBootConfiguration; import org.springframework.context.ConfigurableApplicationContext;@SpringBootConfiguration public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);System.out.println(context.getEnvironment().getProperty("local.ip"));context.close();}}

輸出：

192.168.1.1

方法二：

新建UserConfig.java

package com.edu.spring;import org.springframework.beans.factory.annotation.Autowired; import org.springframework.core.env.Environment; import org.springframework.stereotype.Component;@Component public class UserConfig {@Autowiredprivate Environment environment;public void show(){System.out.println("local.ip=" + environment.getProperty("local.ip"));}}

修改App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);context.getBean(UserConfig.class).show();context.close();}}

同樣可以輸出local.ip=192.168.1.1

方法三：

修改UserConfig.java, 使用@Value("${local.port}")注釋，來獲取

package com.edu.spring;import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Value; import org.springframework.core.env.Environment; import org.springframework.stereotype.Component;@Component public class UserConfig {@Value("${local.port}")private String localPort;/*** @Value 默認要有配置項，配置項可以為空，如果沒有配置項，則可以給默認值*/@Value("${tomcat.port:9090}")private String tomcatPort;@Autowiredprivate Environment environment;public void show(){System.out.println("local.ip=" + environment.getProperty("local.ip"));System.out.println("local.port=" + localPort);System.out.println("name=" + environment.getProperty("name"));System.out.println("app.name=" + environment.getProperty("app.name"));System.out.println("tomcat.port=" + tomcatPort);}}

使用配置文件引用其他變量

public void show(){System.out.println("local.ip=" + environment.getProperty("local.ip"));System.out.println("local.port=" + localPort);System.out.println("name=" + environment.getProperty("name"));System.out.println("app.name=" + environment.getProperty("app.name"));}

application.properties的位置是resources目錄下(即classpath根目錄)或者是resources/config目錄(即classpath:/config目錄)下。

如果要改application.properties的名字和目錄如何做？

可以在intellij工具 Program argument添加參數 --spring.config.name=文件名可以省略文件擴展名

如果修改目錄添加參數 --spring.config.location=classpath:conf/app.properties，? 必須指定擴展名。還可以指定多個路徑，用逗號隔開。之間的指定方式有兩種1.classpath: 2.file:

如果要加載其他配置文件，如何做？

新建jdbc.properties

url=jdbc:mysql:///springboot driverClassName=com.mysql.jdbc.Driver

新建FileConfig.java

package com.edu.spring;import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.PropertySource;@Configuration @PropertySource("classpath:jdbc.properties") public class FileConfig { }

新建JdbcConfig.java

package com.edu.spring;import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component;@Component public class JdbcConfig {@Value("${url}")private String url;@Value("${driverClassName}")private String driverClassName;public void show(){System.out.println("url=" + url);System.out.println("driverClassName=" + driverClassName);}}

在App.java中

context.getBean(JdbcConfig.class).show();

可以正常輸出。

如果是多個路徑下的文件，修改FileConfig.java

或者使用

package com.edu.spring;import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.PropertySource; import org.springframework.context.annotation.PropertySources;@Configuration @PropertySources({@PropertySource("classpath:jdbc.properties"),@PropertySource("file:/e/tmp/jdbc.properties")}) public class FileConfig { }

新建DataSourceProperties.java

package com.edu.spring;import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.context.annotation.PropertySource; import org.springframework.stereotype.Component;@Component @ConfigurationProperties(prefix = "ds") @PropertySource("classpath:/ds.properties") public class DataSourceProperties {private String url;private String driverClassName;private String username;private String password;public void show(){System.out.println("url:" + url);System.out.println("driverClassName:" + driverClassName);System.out.println("username:" + username);System.out.println("password:" + password);}public String getUrl() {return url;}public void setUrl(String url) {this.url = url;}public String getDriverClassName() {return driverClassName;}public void setDriverClassName(String driverClassName) {this.driverClassName = driverClassName;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;} }

新建ds.properties

ds.url=jdbc:mysql:///springboot ds.driverClassName=com.mysql.jdbc.Driver ds.username=root ds.password=123456

springboot 也可以使用application.yml作為配置文件，是使用縮進方式書寫。

從配置文件中，注入集合與數組

新建TomcatProperties.java

package com.edu.spring;import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.stereotype.Component;import java.util.ArrayList; import java.util.Arrays; import java.util.List;@Component @ConfigurationProperties("ds") public class TomcatProperties {private List<String> hosts = new ArrayList<>();private String[] ports;@Overridepublic String toString() {return "TomcatProperties{" +"hosts=" + hosts +", ports=" + Arrays.toString(ports) +'}';}public String[] getPorts() {return ports;}public void setPorts(String[] ports) {this.ports = ports;}public List<String> getHosts() {return hosts;}public void setHosts(List<String> hosts) {this.hosts = hosts;} }

applicatioin.properties

ds.hosts[0]=192.168.1.100 ds.hosts[1]=192.168.1.101 ds.hosts[2]=192.168.1.102 ds.ports[0]=8080 ds.ports[1]=8081 ds.ports[2]=8082

App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);System.out.println(context.getBean(TomcatProperties.class));context.close();}}

注入正常。輸出結果：

TomcatProperties{hosts=[192.168.1.100, 192.168.1.101, 192.168.1.102], ports=[8080, 8081, 8082]}

動態引入配置文件，使用EnvironmentPostProcessor接口

新建MyEnvironmentPostProcessor.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.env.EnvironmentPostProcessor; import org.springframework.core.env.ConfigurableEnvironment; import org.springframework.core.env.PropertiesPropertySource; import org.springframework.stereotype.Component;import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.util.Properties;@Component public class MyEnvironmentPostProcessor implements EnvironmentPostProcessor {@Overridepublic void postProcessEnvironment(ConfigurableEnvironment environment, SpringApplication application) {try(InputStream inputStream = new FileInputStream("F:/test/springboot.properties")){Properties properties = new Properties();properties.load(inputStream);PropertiesPropertySource propertySource = new PropertiesPropertySource("my", properties);environment.getPropertySources().addLast(propertySource);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}} }

測試輸出

System.out.println(context.getEnvironment().getProperty("springboot.name"));

輸出結果為Null

說明沒有正確注入，在resources目錄下新建META-INF/spring.factories，內容如下:

org.springframework.boot.env.EnvironmentPostProcessor=com.edu.spring.MyEnvironmentPostProcessor

執行輸出結果正常。原因是EnvironmentPostProcessor接口不屬于spring的，而是屬于Springboot的，因此需要配置到spring.factories。

有了這一功能我們就可以隨意的增加一些配置了，任意讀取配置，即配置文件中心化。

profile，開發階段和上線測試階段是不同的，如何在不同階段載入不同配置

新建application-dev.properties，內容如下

jdbc.url=mysql:jdbc://127.0.0.1/db_springboot_dev

新建application-test.properties，內容如下：

jdbc.url=mysql:jdbc://127.0.0.1/db_springboot_test

App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication public class App {public static void main(String[] args) {SpringApplication application = new SpringApplication(App.class);//application.setAdditionalProfiles("dev");application.setAdditionalProfiles("test");ConfigurableApplicationContext context = application.run(args);System.out.println(context.getBean(TomcatProperties.class));System.out.println(context.getEnvironment().getProperty("springboot.name"));System.out.println(context.getEnvironment().getProperty("jdbc.url"));context.close();}}

這樣就可以實現切換。默認的application.properties也會加進去。

通過啟動參數來控制生效的profile，--spring.profiles.active=test,dev，這樣test和dev便同時啟用了。

新建MyConfig.java

package com.edu.spring;import org.springframework.boot.SpringBootConfiguration; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Profile;@SpringBootConfiguration public class MyConfig {@Beanpublic Runnable createRunable(){System.out.println("===1==");return () -> {};}/*** 當application-test.properties激活之后才裝配這個Bean* @return*/@Bean@Profile("test")public Runnable createRunable2(){System.out.println("===2==");return () -> {};}/*** 當application-dev.properties激活之后才裝配這個Bean* @return*/@Bean@Profile("dev")public Runnable createRunable3(){System.out.println("===3==");return () -> {};}}

可以當具體properties激活時，裝配Bean。profile注釋也可以用在類上，表示當某個profile生效時，使用這個類。

spring boot自動配置

新建接口EncodingConvert.java

package com.edu.spring;public interface EncodingConvert {}

新建實現類GBKEncodingConvert.java

public class GBKEncodingConvert implements EncodingConvert { }

新建實現類UTF8EncodingConvert.java

package com.edu.spring;public class UTF8EncodingConvert implements EncodingConvert { }

新建EncodingConvertConfig.java

package com.edu.spring;import org.springframework.boot.SpringBootConfiguration; import org.springframework.context.annotation.Bean;@SpringBootConfiguration public class EncodingConvertConfig {@Beanpublic EncodingConvert createUTF8EncodingConvert(){return new UTF8EncodingConvert();}@Beanpublic EncodingConvert createGBKEncodingConvert(){return new GBKEncodingConvert();}}

新建App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);System.out.println(System.getProperty("file.encoding"));System.out.println(context.getBeansOfType(EncodingConvert.class));context.close();}}

運行App.java，打印輸出結果如下：

{createUTF8EncodingConvert=com.edu.spring.UTF8EncodingConvert@c9d0d6, createGBKEncodingConvert=com.edu.spring.GBKEncodingConvert@6ccdb29f}

兩個Bean都裝配成功。

新建GBKCondition.java

package com.edu.spring;import org.springframework.context.annotation.Condition; import org.springframework.context.annotation.ConditionContext; import org.springframework.core.type.AnnotatedTypeMetadata;public class GBKCondition implements Condition {@Overridepublic boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) {String encoding = System.getProperty("file.encoding");if(encoding != null){return "gbk".equals(encoding.toLowerCase());}return false;} }

新建UTF8Condition.java

package com.edu.spring;import org.springframework.context.annotation.Condition; import org.springframework.context.annotation.ConditionContext; import org.springframework.core.type.AnnotatedTypeMetadata;public class UTF8Condition implements Condition {@Overridepublic boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) {String encoding = System.getProperty("file.encoding");if(encoding != null){return "utf-8".equals(encoding.toLowerCase());}return false;} }

在intellij 的VMoption參數添加 -Dfile.encoding=GBK

打印輸出：

{createGBKEncodingConvert=com.edu.spring.GBKEncodingConvert@512baff6}

@Conditional 是基于條件的自動配置，一般配合Condition接口一起使用，只有接口（一個或多個）實現類都返回true才裝配，否則不裝配。

它可以用在方法上，則只對該方法起作用，還可以用在類上，則對該類的所有方法起作用。

此外，@Conditional({UTF8Condition.class, GBKCondition.class})，表示兩個條件都返回true才生效。

@ConditionalOnProperty，表示某個屬性等于某個值時。

新建UserConfiguration.java

package com.edu.spring;import org.springframework.boot.SpringBootConfiguration; import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty; import org.springframework.context.annotation.Bean;@SpringBootConfiguration public class UserConfiguration {@Bean@ConditionalOnProperty(name = "runnable.enabled", havingValue = "true")public Runnable createRunnable(){return ()->{};}}

當application.properties中的屬性runnable.enabled=true時，這個Bean才能夠裝配。否則裝配不成功。matchIfMissing表示當這個配置不存在的時候，也為true。

修改UserConfiguration.java

package com.edu.spring;import com.google.gson.Gson; import org.springframework.boot.SpringBootConfiguration; import org.springframework.boot.autoconfigure.condition.ConditionalOnClass; import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty; import org.springframework.context.annotation.Bean;@SpringBootConfiguration public class UserConfiguration {@Bean@ConditionalOnProperty(name = "runnable.enabled", havingValue = "true", matchIfMissing = true)public Runnable createRunnable() {return () -> {};}@Bean@ConditionalOnClass(name = "com.google.gson.Gson")public Runnable createGsonRunnable() {return () -> {};}}

修改pom.xml，添加gson依賴

<dependency><groupId>com.google.code.gson</groupId><artifactId>gson</artifactId><version>2.8.1</version></dependency>

@ConditionalOnClass表示當存在這個“com.google.gson.Gson”類的時候，就裝配這個Bean。

@ConditionalOnMissingClass表示當不存在這個“com.google.gson.Gson”類的時候，就裝配這個Bean。

打印輸出：

{createRunnable=com.edu.spring.UserConfiguration$$Lambda$137/800735172@335b5620, createGsonRunnable=com.edu.spring.UserConfiguration$$Lambda$138/478489615@29a0cdb}

去掉pom.xml中的依賴是，就不會裝配這個bean。

@ConditionalOnBean??根據容器中存在某個bean來進行裝配

修改UserConfiguration.java

@Bean@ConditionalOnBean(name="user")public Runnable createBeanRunnable() {return () -> {};}

運行時輸出：

{createRunnable=com.edu.spring.UserConfiguration$$Lambda$137/698741991@22356acd, createGsonRunnable=com.edu.spring.UserConfiguration$$Lambda$138/669284403@386f0da3}

沒有輸出createBeanRunnable這個Bean，添加User.java

package com.edu.spring;import org.springframework.stereotype.Component;@Component public class User { }

然后運行輸出：

{createRunnable=com.edu.spring.UserConfiguration$$Lambda$138/1934932165@27d4a09, createGsonRunnable=com.edu.spring.UserConfiguration$$Lambda$139/1508038883@7e4204e2, createBeanRunnable=com.edu.spring.UserConfiguration$$Lambda$140/728943498@b7c4869}

說明成功配置了createBeanRunnable這個bean了。

@ConditionalOnMissiongBean??根據容器中不存在某個bean來進行裝配

Spring Boot @Enable*注解工作原理

新建TomcatProperties.java

package com.edu.spring;import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.context.annotation.Profile; import org.springframework.stereotype.Component;@Component @ConfigurationProperties(prefix = "tomcat") public class TomcatProperties {private String host;private String port;@Overridepublic String toString() {return "TomcatProperties{" +"host='" + host + '\'' +", port='" + port + '\'' +'}';}public String getHost() {return host;}public void setHost(String host) {this.host = host;}public String getPort() {return port;}public void setPort(String port) {this.port = port;} }

application.properties

tomcat.host=192.168.1.100 tomcat.port=8080

新建App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);System.out.println(context.getBean(TomcatProperties.class));context.close();}}

運行輸出結果：

TomcatProperties{host='192.168.1.100', port='8080'}

當我們修改App.java的注解時，

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.boot.context.properties.EnableConfigurationProperties; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.ComponentScan;/*** @EnableConfiguratinProperties是用來啟用一個特性的，這個特性可以把配置文件的屬性注入到bean里面去*/ @EnableConfigurationProperties @ComponentScan public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);System.out.println(context.getBean(TomcatProperties.class));context.close();}}

程序也可以正常運行，但是當我們將注解@EnableConfiguratinProperties刪掉后，程序就獲取不到properties的內容了。說明是@EnableConfiguratinProperties起了作用。

如何在Springboot中啟動異步？

新建Jeep.java

package com.edu.spring;import org.springframework.stereotype.Component;import java.util.concurrent.TimeUnit;@Component public class Jeep implements Runnable {@Overridepublic void run() {try {for(int i = 1; i<= 10; i++){System.out.println("============" + i);TimeUnit.SECONDS.sleep(1);}}catch (Exception e){e.printStackTrace();}} }

修改App.java

context.getBean(Runnable.class).run(); System.out.println("----end-----");

輸出結果如下：

TomcatProperties{host='192.168.1.100', port='8080'} ============1 ============2 ============3 ============4 ============5 ============6 ============7 ============8 ============9 ============10 ----end-----

說明當run方法執行完之后，才輸出end。如何實現異步？

在App.java上啟動異步，添加注釋：

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.context.properties.EnableConfigurationProperties; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.ComponentScan; import org.springframework.scheduling.annotation.EnableAsync;/*** @EnableConfiguratinProperties是用來啟用一個特性的，這個特性可以把配置文件的屬性注入到bean里面去,一般是和@ConfigurationProperties一起使用* @EnableAsync 啟用異步，一般是和@Async一起使用*/ @EnableConfigurationProperties @EnableAsync @ComponentScan public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);System.out.println(context.getBean(TomcatProperties.class));context.getBean(Runnable.class).run();System.out.println("----end-----");context.close();}}

在Jeep.java的run方法上添加@Async注釋

package com.edu.spring;import org.springframework.scheduling.annotation.Async; import org.springframework.stereotype.Component;import java.util.concurrent.TimeUnit;@Component public class Jeep implements Runnable {@Async@Overridepublic void run() {try {for(int i = 1; i<= 10; i++){System.out.println("============" + i);TimeUnit.SECONDS.sleep(1);}}catch (Exception e){e.printStackTrace();}} }

運行輸出結果如下：

----end----- ============1 ============2 ============3 ============4 ============5 ============6 ============7 ============8 ============9 ============10

說明已經成功異步了。

新建User.java

package com.edu.spring;public class User { }

新建Role.java

package com.edu.spring;public class Role { }

新建App2.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.ComponentScan;@ComponentScan public class App2 {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App2.class, args);context.close();}}

此時App2.java中無法獲取User的Bean和Role的Bean，想獲取的方式是：有很多，之前有講過，例如：@Component。今天講另一種方式：

修改App2.java

添加Import注釋，這樣就可以使用User的Bean了。

@Import注釋也可以導入一個數組，例如：@Import({User.class, Role.class})

此外，@Import還可以到如配置類

新建MyConfiguration.java

package com.edu.spring;import org.springframework.context.annotation.Bean;public class MyConfiguration {@Beanpublic Runnable createRunnable(){return () -> {};}@Beanpublic Runnable createRunnable2(){return () -> {};}}

修改App2.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Import;/*** @Import 用來導入一個或多個類（Bean會被Spring容器托管），或者配置類（配置類里面的bean會被Spring容器托管）*/ @ComponentScan @Import({User.class, Role.class, MyConfiguration.class}) public class App2 {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App2.class, args);System.out.println(context.getBean(User.class));System.out.println(context.getBeansOfType(Runnable.class));context.close();} }

使用Import導入MyConfiguration，輸出結果：

com.edu.spring.User@6f27a732 {jeep=com.edu.spring.Jeep@6c779568, createRunnable=com.edu.spring.MyConfiguration$$Lambda$93/1730704097@f381794, createRunnable2=com.edu.spring.MyConfiguration$$Lambda$94/726379593@2cdd0d4b}

說明成功導入了配置類。

ImportSelector是什么？

新建MyImportSelector.java

修改App2.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Import;/*** @Import 用來導入一個或多個類（Bean會被Spring容器托管），或者配置類（配置類里面的bean會被Spring容器托管）*/ @ComponentScan //@Import({User.class, Role.class, MyConfiguration.class}) @Import(MyImportSelector.class) public class App2 {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App2.class, args);System.out.println(context.getBean(User.class));System.out.println(context.getBean(Role.class));System.out.println(context.getBeansOfType(Runnable.class));context.close();}}

同樣可以輸出User的Bean，Role的Bean以及Runnable的Bean，說明裝配成功。

新建EnableLog.java

package com.edu.spring;import org.springframework.context.annotation.Import;import java.lang.annotation.*;@Retention(RetentionPolicy.RUNTIME) @Target(ElementType.TYPE) @Documented @Import(MyImportSelector.class) public @interface EnableLog {String name(); }

在MyImportSelector.java中修改：

package com.edu.spring;import org.springframework.context.annotation.ImportSelector; import org.springframework.core.type.AnnotationMetadata;/*** ImportSelector的方法的返回值，必須是一個class(全稱),該class會被spring容器托管起來。*/ public class MyImportSelector implements ImportSelector {@Overridepublic String[] selectImports(AnnotationMetadata importingClassMetadata) {System.out.println(importingClassMetadata.getAllAnnotationAttributes(EnableLog.class.getName()));/*** 這里可以獲取到注解的詳細信息。然后根據信息去動態的返回需要被spring容器管理的bean*/return new String[]{"com.edu.spring.User",Role.class.getName(), MyConfiguration.class.getName()};} }

可以輸出注釋的信息。

修改APP2.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Import;/*** @Import 用來導入一個或多個類（Bean會被Spring容器托管），或者配置類（配置類里面的bean會被Spring容器托管）*/ @ComponentScan //@Import({User.class, Role.class, MyConfiguration.class}) @Import(MyImportSelector.class) @EnableLog(name="my springboot") public class App2 {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App2.class, args);System.out.println(context.getBean(User.class));System.out.println(context.getBean(Role.class));System.out.println(context.getBeansOfType(Runnable.class));context.close();}}

輸出結果可以輸出{name=[my springboot]}，可以獲取到注解的詳細信息

@EnableAutoConfiguration深入分析

新建App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);System.out.println(context.getBean(Runnable.class));context.close();} }

運行報錯，因為沒有Runnable這個bean。

新建項目：corebean

pom.xml文件：

新建RunnableConfiguration.java

package com.edu.core.bean;import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration;@Configuration public class RunnableConfiguration {@Beanpublic Runnable createRunnable(){return () -> {};}}

在springcourse項目的pom.xml中添加corebean項目依賴：

在次運行App.java

同樣顯示沒有找到Runnable的bean類。

如果spring只支持當前項目中加載配置，那么他的擴展性太不好了，如何解決這個第三方jar的配置？

使用EnableAutoConfiguration注解

修改App.java，我們只用@EnableAutoConfiguration和@ComponentScan注釋

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.EnableAutoConfiguration; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.ComponentScan;/*** EnableAutoConfiguration 作用：從classpath中搜索所有META-INF/spring.factories配置文件，* 然后，將其中org.springframework.boot.autoconfigure.EnableAutoConfiguration key對應的配置項加載到spring容器中*/ @EnableAutoConfiguration @ComponentScan public class App {public static void main(String[] args) {ConfigurableApplicationContext context = SpringApplication.run(App.class, args);System.out.println(context.getBean(Runnable.class));context.close();} }

在resources目錄下創建META-INF/spring.factories，內容如下：

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.edu.core.bean.RunnableConfiguration

運行App.java，輸出如下：

com.edu.core.bean.RunnableConfiguration$$Lambda$134/549293029@398dada8

成功注入進去了Runnable的Bean。

如何配置多個？

在core-bean中新建User.java和Role.java以及一個配置類UserConfiguration.java內容分別如下：

package com.edu.core.bean;public class User { } package com.edu.core.bean;public class Role { } package com.edu.core.bean;import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration;@Configuration public class UserConfiguration {@Beanpublic User createUser(){return new User();} }

然后在springcourse的spring.factories中內容如下：

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.edu.core.bean.RunnableConfiguration,com.edu.core.bean.UserConfiguration,com.edu.core.bean.Role

同樣成功注入進去了。這樣就實現了添加多個配置類。

只有在application.properties 文件中，spring.boot.enableautoconfiguration為true(默認為true)時，才啟用自動配置。默認不用配置時為true

其內部實現的關鍵點有：
?1. ImportSelector 該接口的方法的額返回值都會被納入到spring容器管理中
?2. SpringFactoriesLoader 該類可以從classpath中搜索所有META-INF/spring.factories配置文件，并讀取配置

?如果想要排除某些類，應該如何做？

方式一：通過class來排除

使用exclude

使用@EnableAutoConfiguration(exclude = UserConfiguration.class) 就將User的bean排除在外了。

方式二：通過類名來排除

使用@EnableAutoConfiguration(excludeName = "com.edu.core.bean.Role")

Springboot 事件監聽

事件流程：

? ? 1. 自定義事件，一般是繼承ApplicationEvent抽象類

? ? 2. 定義時間監聽器，一般是實現ApplicationListener接口

? ? 3. 啟動的時候，需要把監聽器加入到spring容器中

? ? 4. 發布事件，使用ApplicationContext的publishEvent發布事件

? ? 5. 配置監聽器

????? ? a. SpringApplication.addListeners 添加監聽器

????? ? b. 把監聽器納入到spring容器中管理 @Component

????? ? c. 可以使用配置項，在application.properties中配置context.listener.classes=com.edu.spring.MyApplicationListener? ?詳細內容參數：DelegatingApplicationListener

定義事件，新建MyApplicationEvent.java

package com.edu.spring;import org.springframework.context.ApplicationEvent;/*** 定義事件*/ public class MyApplicationEvent extends ApplicationEvent {public MyApplicationEvent(Object source) {super(source);} }

定義監聽器，MyApplicationListener.java

package com.edu.spring;import org.springframework.context.ApplicationListener;public class MyApplicationListener implements ApplicationListener<MyApplicationEvent> {@Overridepublic void onApplicationEvent(MyApplicationEvent event) {System.out.println("接收到事件:" + event.getClass());} }

新建App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.EnableAutoConfiguration; import org.springframework.context.ConfigurableApplicationContext; import org.springframework.context.annotation.ComponentScan;@EnableAutoConfiguration(excludeName = "com.edu.core.bean.Role") @ComponentScan public class App {public static void main(String[] args) {SpringApplication application = new SpringApplication(App.class);application.addListeners(new MyApplicationListener());ConfigurableApplicationContext context = application.run(args);//發布事件context.publishEvent(new MyApplicationEvent(new Object()));context.close();} }

運行結果：

接收到事件:class com.edu.spring.MyApplicationEvent

說明監聽成功。

除了使用application.addListeners(new MyApplicationListener());這種方式添加監聽器，還有什么方式？

可以使用@Component注釋給MyApplicationListener.java。這樣也可以。

另一種方式配置監聽器：新建MyEventHandler.java

package com.edu.spring;import org.springframework.context.event.EventListener; import org.springframework.stereotype.Component;@Component public class MyEventHandle {/*** 參數一定要是ApplicationEvent,或者其子類* @param event*/@EventListenerpublic void event(MyApplicationEvent event){System.out.println("接受到事件" + event.getClass());}}

使用注解@EventListener也可以配置監聽器，且該類需要納入到spring容器重管理（詳細內容參照EventListenerFactory和EventListenerMethodProcessor），不用其他的配置了。如果參數設置成public void event(Object event) 那么所有的事件都能夠接收到。?

spring或者Springboot內部有哪些已經定義好的事件？

修改MyEventHandle.java

package com.edu.spring;import org.springframework.context.event.ContextStoppedEvent; import org.springframework.context.event.EventListener; import org.springframework.stereotype.Component;@Component public class MyEventHandle {/*** 參數一定要是ApplicationEvent,或者其子類* @param event*/@EventListenerpublic void event(MyApplicationEvent event){System.out.println("接受到事件" + event.getClass());}@EventListenerpublic void event2(ContextStoppedEvent event){System.out.println("應用停止事件：" + event);}}

在App.java中修改：

context.publishEvent(new MyApplicationEvent(new Object()));

輸出結果：

接受到事件class com.edu.spring.MyApplicationEvent 應用停止事件：org.springframework.context.event.ContextStoppedEvent[source=org.springframework.context.annotation.AnnotationConfigApplicationContext@314c508a, started on Thu Apr 25 17:07:00 CST 2019]

監聽器起作用了。

spring boot擴展分析

新建MyApplicationContextInitializer.java

package com.edu.spring;import org.springframework.context.ApplicationContextInitializer; import org.springframework.context.ConfigurableApplicationContext;public class MyApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {@Overridepublic void initialize(ConfigurableApplicationContext applicationContext) {System.out.println("bean count: " + applicationContext.getBeanDefinitionCount());} }

新建MyApplicationContextInitializer2.java

package com.edu.spring;import org.springframework.context.ApplicationContextInitializer; import org.springframework.context.ConfigurableApplicationContext;public class MyApplicationContextInitializer2 implements ApplicationContextInitializer<ConfigurableApplicationContext> {@Overridepublic void initialize(ConfigurableApplicationContext applicationContext) {System.out.println("app name: " + applicationContext.getDisplayName());} }

新建App.java

package com.edu.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication public class App {public static void main(String[] args) {SpringApplication application = new SpringApplication(App.class);application.addInitializers(new MyApplicationContextInitializer());ConfigurableApplicationContext context = application.run(args);context.stop();context.close();} }

在application.properties中內容如下：

context.initializer.classes=com.edu.spring.MyApplicationContextInitializer, com.edu.spring.MyApplicationContextInitializer2

運行App.java

輸出結果如下：

bean count: 5 app name: org.springframework.context.annotation.AnnotationConfigApplicationContext@1a052a00

ApplicationContextInitializer 接口是在spring容器執行refreshed之前的一個回調
?使用步驟：
? ? ?1. 寫一個類，實現ApplicationContextInitializer接口
? ? ?2. 注冊ApplicationContextInitializer

?注冊方法：
? ? ?1. SpringApplication.addInitializers()
? ? ?2. 通過application.properties 配置context.initializer.classes=com.edu.spring.MyApplicationContextInitializer來進行,可以指定多個，多個用逗號隔開
? ? ?3. 通過spring.factories機制,(注冊listener監聽器也可以使用這種方式)

下面詳細說明如何通過spring.factories實現。

新建項目initializer。

其中pom.xml內容如下:

<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.edu.spring</groupId><artifactId>initializer</artifactId><version>1.0-SNAPSHOT</version><properties><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><maven.compiler.source>1.8</maven.compiler.source><maven.compiler.target>1.8</maven.compiler.target></properties><dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>2.1.4.RELEASE</version><scope>import</scope><type>pom</type></dependency></dependencies></dependencyManagement><dependencies><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency></dependencies></project>

新建EchoApplicationContextInitializer.java

package com.edu.spring.initializer;import org.springframework.context.ApplicationContextInitializer; import org.springframework.context.ConfigurableApplicationContext;public class EchoApplicationContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {@Overridepublic void initialize(ConfigurableApplicationContext configurableApplicationContext) {System.out.println("===EchoApplicationContextInitializer====");} }

在resources下新建META-INF/spring.factories，內容如下：

org.springframework.context.ApplicationContextInitializer=com.edu.spring.initializer.EchoApplicationContextInitializer

然后在springcourse項目的pom中導入Initializer項目

<dependency><groupId>com.edu.spring</groupId><artifactId>initializer</artifactId><version>1.0-SNAPSHOT</version></dependency>

運行App.java，執行結果如下：

bean count: 5 app name: org.springframework.context.annotation.AnnotationConfigApplicationContext@ca263c2 ===EchoApplicationContextInitializer====

說明成功注入。

CommandLineRunner接口回調

在springboot項目中，新建ServerSuccessReport.java

package com.edu.spring;import org.springframework.boot.CommandLineRunner; import org.springframework.stereotype.Component;@Component public class ServerSuccessReport implements CommandLineRunner {@Overridepublic void run(String... args) throws Exception {System.out.println("=====應用已經成功啟動=====");} }

運行結果如下：

bean count: 5 app name: org.springframework.context.annotation.AnnotationConfigApplicationContext@27c6e487 ===EchoApplicationContextInitializer==== 2019-04-26 15:33:13.441 INFO 1396 --- [ main] com.edu.spring.App : Starting App on DESKTOP-AQM2529 with PID 1396 (E:\git\springcourse\target\classes started by vincent in E:\git\springcourse) 2019-04-26 15:33:13.443 INFO 1396 --- [ main] com.edu.spring.App : No active profile set, falling back to default profiles: default 2019-04-26 15:33:14.150 INFO 1396 --- [ main] com.edu.spring.App : Started App in 1.013 seconds (JVM running for 1.577) =====應用已經成功啟動=====

從輸出結果中可以看到，在Started App啟動之后，輸出CommandLineRunner接口方法。

CommandLineRunner ApplicationRunner接口是在容器啟動成功后的最后一步的回調。類似開機自啟動

使用步驟：

? ? 1. 寫一個類，實現CommandLineRunner接口

? ? 2. 把該類納入到Spring容器中

? ? 3. 可以通過@Order注解或者Ordered接口來控制執行順序

如果有多個類實現了CommandLineRunner接口，如何保證執行順序？

新建ServerStartedReport.java

package com.edu.spring;import org.springframework.boot.CommandLineRunner; import org.springframework.stereotype.Component;import java.time.LocalDateTime;@Component public class ServerStartedReport implements CommandLineRunner {@Overridepublic void run(String... args) throws Exception {System.out.println("=========應用啟動后的時間是：" + LocalDateTime.now().toString());} }

運行App.java，結果如下：

bean count: 5 app name: org.springframework.context.annotation.AnnotationConfigApplicationContext@7ff2a664 ===EchoApplicationContextInitializer==== 2019-04-26 15:44:03.081 INFO 2656 --- [ main] com.edu.spring.App : Starting App on DESKTOP-AQM2529 with PID 2656 (E:\git\springcourse\target\classes started by vincent in E:\git\springcourse) 2019-04-26 15:44:03.084 INFO 2656 --- [ main] com.edu.spring.App : No active profile set, falling back to default profiles: default 2019-04-26 15:44:03.775 INFO 2656 --- [ main] com.edu.spring.App : Started App in 1.0 seconds (JVM running for 1.426) =========應用啟動后的時間是：2019-04-26T15:44:03.784 =====應用已經成功啟動=====

如果我們想要ServerSuccessReport類先執行，可以使用@Order注釋。

@Order(3) @Component public class ServerStartedReport implements CommandLineRunner {@Overridepublic void run(String... args) throws Exception {System.out.println("=========應用啟動后的時間是：" + LocalDateTime.now().toString());} } @Order(2) @Component public class ServerSuccessReport implements CommandLineRunner {@Overridepublic void run(String... args) throws Exception {System.out.println("=====應用已經成功啟動=====");} }

只要Order括號內的數字越小，則越先執行。

新建StartedApplicationRunner.java

package com.edu.spring;import org.springframework.boot.ApplicationArguments; import org.springframework.boot.ApplicationRunner; import org.springframework.stereotype.Component;import java.util.Arrays;@Component public class StartedApplicationRunner implements ApplicationRunner {@Overridepublic void run(ApplicationArguments args) throws Exception {System.out.println("應用已經啟動，參數為：" + Arrays.deepHashCode(args.getSourceArgs()));} }

修改ServerSuccessReport.java的輸出

@Overridepublic void run(String... args) throws Exception {System.out.println("=====應用已經成功啟動=====" + Arrays.asList(args));}

App.java添加參數：

運行App.java，結果如下：

bean count: 5 app name: org.springframework.context.annotation.AnnotationConfigApplicationContext@78a2da20 ===EchoApplicationContextInitializer==== 2019-04-26 16:04:07.136 INFO 1684 --- [ main] com.edu.spring.App : Starting App on DESKTOP-AQM2529 with PID 1684 (E:\git\springcourse\target\classes started by vincent in E:\git\springcourse) 2019-04-26 16:04:07.138 INFO 1684 --- [ main] com.edu.spring.App : No active profile set, falling back to default profiles: default 2019-04-26 16:04:07.832 INFO 1684 --- [ main] com.edu.spring.App : Started App in 0.994 seconds (JVM running for 1.458) =====應用已經成功啟動=====[aa, bb] =========應用啟動后的時間是：2019-04-26T16:04:07.844 應用已經啟動，參數為：[aa, bb]

CommandLineRunner ApplicationRunner區別：

區別在于方法的參數不一樣，CommandLineRunner的參數為最原始參數，沒有做任何處理，ApplicationRunner的參數是ApplicationArguments,是對原始參數做了進一步的封裝。

進一步說明ApplicationArguments的作用。

修改App.java

@SpringBootApplication public class App {public static void main(String[] args) {SpringApplication application = new SpringApplication(App.class);//application.addInitializers(new MyApplicationContextInitializer());ConfigurableApplicationContext context = application.run(args);ApplicationArguments arguments = context.getBean(ApplicationArguments.class);System.out.println(arguments.getSourceArgs().length);System.out.println(arguments.getOptionNames());System.out.println(arguments.getOptionValues("myname"));context.stop();context.close();} }

修改Intellij 的運行參數，Program arguments 為 --myname admin，運行輸出結果如下：

bean count: 5 app name: org.springframework.context.annotation.AnnotationConfigApplicationContext@6a79c292 ===EchoApplicationContextInitializer==== 2019-04-26 16:19:12.343 INFO 8216 --- [ main] com.edu.spring.App : Starting App on DESKTOP-AQM2529 with PID 8216 (E:\git\springcourse\target\classes started by vincent in E:\git\springcourse) 2019-04-26 16:19:12.346 INFO 8216 --- [ main] com.edu.spring.App : No active profile set, falling back to default profiles: default 2019-04-26 16:19:13.001 INFO 8216 --- [ main] com.edu.spring.App : Started App in 0.959 seconds (JVM running for 1.401) =====應用已經成功啟動=====[--myname, admin] =========應用啟動后的時間是：2019-04-26T16:19:13.010 應用已經啟動，參數為：[--myname, admin] 2 [myname] []

修改Intellij 的運行參數，Program arguments 為 --myname=admin，運行輸出結果如下：

bean count: 5 app name: org.springframework.context.annotation.AnnotationConfigApplicationContext@78a2da20 ===EchoApplicationContextInitializer==== 2019-04-26 16:20:08.312 INFO 11652 --- [ main] com.edu.spring.App : Starting App on DESKTOP-AQM2529 with PID 11652 (E:\git\springcourse\target\classes started by vincent in E:\git\springcourse) 2019-04-26 16:20:08.315 INFO 11652 --- [ main] com.edu.spring.App : No active profile set, falling back to default profiles: default 2019-04-26 16:20:08.956 INFO 11652 --- [ main] com.edu.spring.App : Started App in 0.939 seconds (JVM running for 1.469) =====應用已經成功啟動=====[--myname=admin] =========應用啟動后的時間是：2019-04-26T16:20:08.961 應用已經啟動，參數為：[--myname=admin] 1 [myname] [admin]

ApplicationArguments是對參數(main方法)，做了進一步處理

可以解析 --name=value的，我們就可以通過name來獲取value。如果我們用原始的方法進行獲取參數時，還得需要對參數進行分割。

Springboot補充講解

我們知道@SpringBootApplication注解有三個注解所組成的，分別是：@SpringBootConfiguration @EnableAutoConfiguration @ComponentScan

在com.edu.spring.springboot包下面新建App.java

package com.edu.spring.springboot;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication public class App {public static void main(String[] args) {SpringApplication application = new SpringApplication(App.class);ConfigurableApplicationContext context = application.run(args);System.out.println(context.getBean(Runnable.class));context.close();} }

在com.edu.spring.bean包下新建RunnableConfiguration.java

package com.edu.spring.bean;import org.springframework.boot.SpringBootConfiguration; import org.springframework.context.annotation.Bean;@SpringBootConfiguration public class RunnableConfiguration {@Beanpublic Runnable createRunnable(){return ()->{};}}

運行App.java輸出結果如下：

說明沒有成功注入。原因是@SpringBootApplication掃描的是當前包和子包下面的所有類。但是同一級的包是無法掃描到的。可以通過basePackage來指定。修改App.java如下：

package com.edu.spring.springboot;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.context.ConfigurableApplicationContext;@SpringBootApplication(scanBasePackages = "com.edu.spring") public class App {public static void main(String[] args) {SpringApplication application = new SpringApplication(App.class);ConfigurableApplicationContext context = application.run(args);System.out.println(context.getBean(Runnable.class));context.close();} }

這樣就成功注入了。

排除某些類，方法如下：

修改pom.xml，添加gson依賴。

<dependency><groupId>com.google.code.gson</groupId><artifactId>gson</artifactId></dependency>

因為gson依賴，已經在springboot父類中定義，所以不需要指定version。

修改RunnableConfiguration.java

@Beanpublic Gson createGson(){return new Gson();}

修改App.java

System.out.println(context.getBean(Gson.class));

輸出結果正常。說明成功注入進去。

排除Gson的bean。修改App.java

@SpringBootApplication(scanBasePackages = "com.edu.spring", exclude = GsonAutoConfiguration.class)

沒有排除掉，目前這有問題。

排除指定類、配置類，exclude：根據class來排除，excludeName：根據class name來排除。

自定義Banner方法

我們每次輸出的時候都會輸出spring的Banner：

如何控制不輸出呢？

修改App.java如下：

SpringApplication application = new SpringApplication(App.class); application.setBannerMode(Banner.Mode.OFF);

這樣就不輸出Spring的Banner了。

還可以自定義Banner，在resources目錄下新建banner.txt

然后就可以執行成功了。注意不要把Banner.Mode.OFF開啟。

第二種方式自定義Banner的方法是，在application.properties文件中寫文件路徑。支持圖片的Banner，圖片的格式支持jpg，png，gif

spring.banner.location=banner2.txt spring.banner.image.location=banner2.jpg

讀取application.properties時如果沒有key則獲取默認的value，方法如下:

方法一：在@value注釋上使用默認的value

@Value(("${server.host:localhost}"))private String serverHosts;

方法二：使用getProperty方法：

System.out.println(context.getEnvironment().getProperty("server.host2","localhost2"));

spring boot 運行流程分析

spingboot的執行入口有兩個分別是：

// 實例化SpringApplication對象，然后調用run方法 SpringApplication application = new SpringApplication(App.class); ConfigurableApplicationContext context = application.run(args); // 直接調用靜態run方法（內部轉換成第一種調用方式） ConfigurableApplicationContext context = SpringApplication.run(App.class, args);

? 運行流程
? ?1. 判斷是否是web環境
? ?2. 加載所有classpath下面的META-INF/spring.factories, ?ApplicationContextInitializerr
? ?3. 加載所有classpath下面的META-INF/spring.factories, ApplicationListener
? ?4. 推斷main方法所在的類
? ?5. 開始執行run方法
? ?6. 設置java.awt.headless系統變量
? ?7. 加載所有classpath下面的META-INF/spring.factories SpringApplicationRunListener
? ?8. 執行所有SpringApplicationRunListener的started方法
? ?9. 實例化ApplicationArguments對象
? ?10. 創建Environment
? ?11. 配置Environment，主要是把run方法的參數配置到Environment
? ?12. 執行所有SpringApplicationRunListener的environment.prepared方法
? ?13. 如果不是web環境，但是是web的Environment，則把web的Environment轉換成標準的Environment
? ?14. 輸出Banner
? ?15. 初始化applicationContext，如果是web環境，則實例化AnnotationConfigEmbeddedWebApplicationContext對象，否則實例化AnnotationConfigApplicationContext對象
? ?16. 如果beanNameGenerator不為空，就把beanNameGenerator對象注入Context里面去
? ?17. 回調所有的ApplicationContextInitializer方法
? ?18. 執行所有SpringApplicationRunListener的contextPrepared方法
? ?19. 依次往Spring容器中注入：ApplicationArguments, Banner
? ?20. 加載所有的源到context里面去。
? ?21. 執行所有SpringApplicationRunListener的contextLoaded方法
? ?22. 執行context的refresh方法，并且調用context的registerShutdownHook方法
? ?23. 回調，獲取容器中所有的ApplicationRunner, CommandLineRunner接口，然后排序，依次調用
? ?24. 執行所有SpringApplicationRunListener的finished的finished方法

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编程问答

springboot教程（一）

使用jdk:1.8、maven:3.3.3

spring獲取Bean的方式

Bean默認是單例

FactoryBean

使用第三種裝配

Bean初始化，在Bean初始化時，進行一些操作。

方式一：

方法二：

方式三：

Bean裝配

依賴注入

方法一：使用Qualifier注釋

方法二：使用Primary注釋Bean

第二課

讓Bean獲取Spring容器

新建myConfig.java

方法一：

方法二：

方法三：

代理對象

spring擴展二

springboot-1

Springboot配置文件

方法一 使用context.getEnvironment().getProperty("local.ip")

方法二：

方法三：

profile，開發階段和上線測試階段是不同的，如何在不同階段載入不同配置

spring boot自動配置

Spring Boot @Enable*注解工作原理

如何在Springboot中啟動異步？

@EnableAutoConfiguration深入分析

Springboot 事件監聽

事件流程：

spring boot擴展分析

Springboot補充講解

spring boot 運行流程分析

總結

方法一使用context.getEnvironment().getProperty("local.ip")