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springboot 获取bean_SpringBoot高级(自动配置事件监听监控)

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SpringBoot自動(dòng)配置

condition-1

Condition是Spring4.0后引入的條件化配置接口，通過實(shí)現(xiàn)Condition接口可以完成有條件的加載相應(yīng)的Bean

@Conditional要配和Condition的實(shí)現(xiàn)類(ClassCondition)進(jìn)行使用

ClassCondition

public?class?ClassCondition?implements?Condition?{????/**?????*?????*?@param context 上下文對(duì)象。用于獲取環(huán)境，IOC容器，ClassLoader對(duì)象?????*?@param metadata 注解元對(duì)象。?可以用于獲取注解定義的屬性值?????*?@return?????*/????@Override????public?boolean?matches(ConditionContext?context,?AnnotatedTypeMetadata?metadata)?{??????????????//1.需求：?導(dǎo)入Jedis坐標(biāo)后創(chuàng)建Bean????????//思路：判斷redis.clients.jedis.Jedis.class文件是否存在????????boolean?flag?=?true;????????try?{????????????Class>?cls?=?Class.forName("redis.clients.jedis.Jedis");????????}?catch?(ClassNotFoundException?e)?{????????????flag?=?false;????????}????????return?flag;??????????}}

UserConfig

@Configurationpublic?class?UserConfig?{????@Bean????@Conditional(ClassCondition.class)????public?User?user(){????????return?new?User();????}}

測(cè)試

@SpringBootApplicationpublic?class?SpringbootConditionApplication?{????public?static?void?main(String[]?args)?{????????//啟動(dòng)SpringBoot的應(yīng)用，返回Spring的IOC容器????????ConfigurableApplicationContext?context?=?SpringApplication.run(SpringbootConditionApplication.class,?args);????????Object?user?=?context.getBean("user");????????System.out.println(user);????}}

依賴

????????????????????redis.clients????????????jedis????????

這一段是判斷jedis這個(gè)依賴要有沒有來決定是否生成對(duì)應(yīng)的bean對(duì)象，需要實(shí)現(xiàn)Condition接口，重寫mathes方法，返回false則不創(chuàng)建對(duì)象，在這個(gè)user對(duì)象上加入注解@Conditioal(xxx.class)來實(shí)現(xiàn)判斷。

Condition-2

需求：將類的判斷定義為動(dòng)態(tài)的。判斷哪個(gè)字節(jié)碼文件存在可以動(dòng)態(tài)指定。

自定義條件注解類

import?org.springframework.context.annotation.Conditional;import?java.lang.annotation.*;@Target({ElementType.TYPE,?ElementType.METHOD})@Retention(RetentionPolicy.RUNTIME)@Documented@Conditional(ClassCondition.class)public?@interface?ConditionOnClass?{????String[]?value();}

**注意：**此處@ConditionOnClass為自定義注解

@Configurationpublic?class?UserConfig?{????@Bean????//@Conditional(ClassCondition.class)????@ConditionOnClass("com.alibaba.fastjson.JSON")????public?User?user(){????????return?new?User();????}????@Bean????@ConditionalOnProperty(name?=?"itcast",havingValue?=?"ii")????public?User?user2(){????????return?new?User();????}}

測(cè)試User對(duì)象的創(chuàng)建

自定義注解其實(shí)是對(duì)原來注解的封裝
@ConditionalOnProperty是看配置文件中是否存在一個(gè)這樣的鍵值對(duì)，如果有則創(chuàng)建、
-執(zhí)行順序：
@ConditionOnClass的value值，找到依賴和自定義注解類，通過自定義注解類上的class找到具體要執(zhí)行的代碼，決定是否生成bean對(duì)象。

查看條件注解源碼

SpringBoot 提供的常用條件注解：

ConditionalOnProperty：判斷配置文件中是否有對(duì)應(yīng)屬性和值才初始化Bean

ConditionalOnClass：判斷環(huán)境中是否有對(duì)應(yīng)字節(jié)碼文件才初始化Bean

ConditionalOnMissingBean：判斷環(huán)境中沒有對(duì)應(yīng)Bean才初始化Bean

SpringBoot自動(dòng)配置-切換內(nèi)置web服務(wù)器

查看繼承關(guān)系圖

排除Tomcat

pom文件中的排除依賴效果

?????????????org.springframework.boot????????????spring-boot-starter-web????????????????????????????????????????????????????????????spring-boot-starter-tomcat????????????????????org.springframework.boot????????????????????????????????????????????????????????????????spring-boot-starter-jetty????????????org.springframework.boot????????

SpringBoot自動(dòng)配置-Enable注解原理

SpringBoot不能直接獲取在其他工程中定義的Bean

演示代碼：

springboot-enable工程

/**?*?@ComponentScan 掃描范圍：當(dāng)前引導(dǎo)類所在包及其子包?*?*?com.itheima.springbootenable?*?com.itheima.config?*?//1.使用@ComponentScan掃描com.itheima.config包?*?//2.可以使用@Import注解，加載類。這些類都會(huì)被Spring創(chuàng)建，并放入IOC容器?*?//3.可以對(duì)Import注解進(jìn)行封裝。?*///@ComponentScan("com.itheima.config")//@Import(UserConfig.class)@EnableUser@SpringBootApplicationpublic?class?SpringbootEnableApplication?{????public?static?void?main(String[]?args)?{????????ConfigurableApplicationContext?context?=?SpringApplication.run(SpringbootEnableApplication.class,?args);?????//獲取Bean????????Object?user?=?context.getBean("user");????????System.out.println(user);?}}

pom中引入springboot-enable-other

???????????????com.itheima??????????springboot-enable-other????????????0.0.1-SNAPSHOT??????

springboot-enable-other工程

UserConfig

@Configurationpublic?class?UserConfig?{????@Bean??public?User?user()?{????????return?new?User();??}}

EnableUser注解類

import?org.springframework.context.annotation.Import;import?java.lang.annotation.*;@Target(ElementType.TYPE)@Retention(RetentionPolicy.RUNTIME)@Documented@Import(UserConfig.class)public?@interface?EnableUser?{

myImportSelector

?public?class?MyImportSelector?implements?ImportSelector?{??????@Override??????public?String[]?selectImports(AnnotationMetadata?importingClassMetadata)?{??????????return?new?String[]{"com.itheima.domain.User",?"com.itheima.domain.Role"};??????}??}

ImportBeanDefinitionRegistrar 實(shí)現(xiàn)類

public?class?MyImportBeanDefinitionRegistrar?implements?ImportBeanDefinitionRegistrar?{????@Override????public?void?registerBeanDefinitions(AnnotationMetadata?importingClassMetadata,?BeanDefinitionRegistry?registry)?{????????AbstractBeanDefinition?beanDefinition?=?BeanDefinitionBuilder.rootBeanDefinition(User.class).getBeanDefinition();????????registry.registerBeanDefinition("user",?beanDefinition);????}}

Import4中用法：

1.導(dǎo)入Bean

2.導(dǎo)入配置類
3.導(dǎo)入ImportSelector的實(shí)現(xiàn)類。
4.導(dǎo)入ImportBeanDefinitionRegistrar實(shí)現(xiàn)類

自定義依賴

SpringBoot事件監(jiān)聽

Java中的事件監(jiān)聽機(jī)制定義了以下幾個(gè)角色：

①事件：Event，繼承 java.util.EventObject 類的對(duì)象

②事件源：Source ，任意對(duì)象Object

③監(jiān)聽器：Listener，實(shí)現(xiàn) java.util.EventListener 接口的對(duì)象

SpringBoot 在項(xiàng)目啟動(dòng)時(shí)，會(huì)對(duì)幾個(gè)監(jiān)聽器進(jìn)行回調(diào)，我們可以實(shí)現(xiàn)這些監(jiān)聽器接口，在項(xiàng)目啟動(dòng)時(shí)完成一些操作。

ApplicationContextInitializer、
SpringApplicationRunListener、
CommandLineRunner、
ApplicationRunner自定義監(jiān)聽器的啟動(dòng)時(shí)機(jī)：MyApplicationRunner和MyCommandLineRunner都是當(dāng)項(xiàng)目啟動(dòng)后執(zhí)行，使用@Component放入容器即可使用

MyApplicationRunner

/**?*?當(dāng)項(xiàng)目啟動(dòng)后執(zhí)行run方法。?*/@Componentpublic?class?MyApplicationRunner?implements?ApplicationRunner?{????@Override????public?void?run(ApplicationArguments?args)?throws?Exception?{????????System.out.println("ApplicationRunner...run");????????System.out.println(Arrays.asList(args.getSourceArgs()));????}}?

MyCommandLineRunner

@Componentpublic?class?MyCommandLineRunner?implements?CommandLineRunner?{????@Override????public?void?run(String...?args)?throws?Exception?{????????System.out.println("CommandLineRunner...run");????????System.out.println(Arrays.asList(args));????}}

MyApplicationContextInitializer的使用要在resource文件夾下添加META-INF/spring.factories

org.springframework.context.ApplicationContextInitializer=com.itheima.springbootlistener.listener.MyApplicationContextInitializer@Componentpublic?class?MyApplicationContextInitializer?implements?ApplicationContextInitializer?{????@Override????public?void?initialize(ConfigurableApplicationContext?applicationContext)?{????????System.out.println("ApplicationContextInitializer....initialize");????}}

MySpringApplicationRunListener的使用要添加構(gòu)造器(最屌)

public?class?MySpringApplicationRunListener?implements?SpringApplicationRunListener?{????public?MySpringApplicationRunListener(SpringApplication?application,?String[]?args)?{????}????@Override????public?void?starting()?{????????System.out.println("starting...項(xiàng)目啟動(dòng)中");????}????@Override????public?void?environmentPrepared(ConfigurableEnvironment?environment)?{????????System.out.println("environmentPrepared...環(huán)境對(duì)象開始準(zhǔn)備");????}????@Override????public?void?contextPrepared(ConfigurableApplicationContext?context)?{????????System.out.println("contextPrepared...上下文對(duì)象開始準(zhǔn)備");????}????@Override????public?void?contextLoaded(ConfigurableApplicationContext?context)?{????????System.out.println("contextLoaded...上下文對(duì)象開始加載");????}????@Override????public?void?started(ConfigurableApplicationContext?context)?{????????System.out.println("started...上下文對(duì)象加載完成");????}????@Override????public?void?running(ConfigurableApplicationContext?context)?{????????System.out.println("running...項(xiàng)目啟動(dòng)完成，開始運(yùn)行");????}????@Override????public?void?failed(ConfigurableApplicationContext?context,?Throwable?exception)?{????????System.out.println("failed...項(xiàng)目啟動(dòng)失敗");????}}

Springboot Admin圖形化管理平臺(tái)

以后可以server打成jar包，然后其他服務(wù)通過端口去綁定注冊(cè)

Springboot 部署

部署有兩個(gè)方式
1.通過maven或者命令直接打成jar包，通過cmd，直接運(yùn)行jar包即可
2.通過war包啟動(dòng)，pom.xml里加入war，主文件繼承SpringBootServletInitializer，重寫方法，即可

SpringBoot流程分析

初始化

配置啟動(dòng)引導(dǎo)類(判斷是否有啟動(dòng)主類)

判斷是否是Web環(huán)境

獲取初始化類、監(jiān)聽器類

run

啟動(dòng)計(jì)時(shí)器

執(zhí)行監(jiān)聽器

準(zhǔn)備環(huán)境

打印banner：可以resource下粘貼自定義的banner

5.創(chuàng)建context

refreshContext(context);

執(zhí)行refreshContext方法后才真正創(chuàng)建Bean

最后給個(gè)banner

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http://blog.csdn.net/m0_46690280/article/details/108567548

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