Spring MVC 實踐
標(biāo)簽 ： Java與Web
Spring Web MVC
Spring-Web-MVC是一種基于請求驅(qū)動的 輕量級Web-MVC設(shè)計模式框架, Spring MVC使用MVC架構(gòu)思想, 對Web層進(jìn)行職責(zé)解耦 ,使用請求-響應(yīng) 模型將數(shù)據(jù) 、業(yè)務(wù) 與視圖 進(jìn)行分離, 簡化開發(fā).
MVC
MVC(模型-視圖-控制器)是一個以設(shè)計界面應(yīng)用程序為基礎(chǔ) 的架構(gòu)模式,通過分離模型-視圖-控制器在應(yīng)用中的角色將業(yè)務(wù)邏輯從界面中解耦:
模型負(fù)責(zé)封裝應(yīng)用數(shù)據(jù)和業(yè)務(wù)邏輯; 視圖僅負(fù)責(zé)展示數(shù)據(jù); 控制器負(fù)責(zé)接收用戶請求,并調(diào)用模型(Service/Manger/DAO)來處理業(yè)務(wù)邏輯.模型可能會返回一些數(shù)據(jù)需要在視圖層展示,控制器就需要整理模型數(shù)據(jù)并調(diào)用視圖展示. MVC模式的核心思想就是將業(yè)務(wù)邏輯從界面中分離出來,允許它們單獨改變而不會相互影響.
Spring MVC
Spring MVC框架是基于Java語言的MVC架構(gòu)具體實現(xiàn).他的設(shè)計圍繞DispatcherServlet展開,DispatcherServlet負(fù)責(zé)將請求分派給指定的Controller(Handler),通過可配置的HandlerMapping、HandlAdapter、Controller、ViewResolver來處理請求 拿到數(shù)據(jù)并填充對應(yīng)的視圖View :
組件名稱描述 DispatcherServlet 調(diào)度器/前端控制器 DispatcherServlet是前端控制器 模式的具體實現(xiàn)(詳細(xì)可參考Front Controller),他提供了整個Web應(yīng)用的集中訪問點,截獲請求并將其分派給指定的Controller,相當(dāng)于MVC中的C. 他的存在降低了組件之間的耦合性. HandlerMapping 處理器映射器 HandlerMapping負(fù)責(zé)根據(jù)用戶請求URI找到對應(yīng)的Controller與Interceptor,并將它們封裝在HandlerExecutionChain中返回給DispatcherServlet. HandlAdapter 處理器適配器 Spring MVC通過HandlerAdapter執(zhí)行Controller,這是適配器模式 的應(yīng)用,通過擴(kuò)展適配器可以執(zhí)行更多類型的Controller. Controller 處理器 Controller(又稱Handler)是繼DispatcherServlet前端控制器之后的后端控制器 ,在DispatcherServlet的控制下Controller對具體的用戶請求進(jìn)行處理. ViewResolver 視圖解析器 負(fù)責(zé)將Model數(shù)據(jù)填充到View, 組合生成視圖展示:他首先將邏輯視圖名 解析成物理視圖名 ,生成View視圖對象,最后對View進(jìn)行渲染(填充數(shù)據(jù)). Spring默認(rèn)提供了針對JSP/Velocity/PFD等視圖的ViewResolver實現(xiàn).
初識Spring MVC
需求: 用戶列表查詢.
mvn archetype:generate -DgroupId=com.fq.mvc -
DartifactId =MVC
-
DarchetypeArtifactId =maven-archetype-webapp
-
DinteractiveMode =false
-
DarchetypeCatalog =internal依賴管理 Spring 、Spring MVC 、 Sevlet 及Velocity 依賴: <dependency > <groupId > org.springframework
</groupId > <artifactId > spring-core
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-context
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-context-support
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-beans
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-expression
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-web
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-test
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > javax.servlet
</groupId > <artifactId > javax.servlet-api
</artifactId > <version > ${servlet.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-webmvc
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.apache.velocity
</groupId > <artifactId > velocity
</artifactId > <version > ${velocity.version}
</version >
</dependency >
<dependency > <groupId > org.apache.velocity
</groupId > <artifactId > velocity-tools
</artifactId > <version > ${velocity.tools.version}
</version >
</dependency >
配置DispatcherServlet(web.xml) <?xml version="1.0" encoding="UTF-8"?>
<web-app version ="3.0" xmlns ="http://java.sun.com/xml/ns/javaee" xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation ="http://java.sun.com/xml/ns/javaeehttp://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" > <display-name > MVC
</display-name > <servlet > <servlet-name > mvc
</servlet-name > <servlet-class > org.springframework.web.servlet.DispatcherServlet
</servlet-class > <init-param > <param-name > contextConfigLocation
</param-name > <param-value > classpath:spring/mvc-servlet.xml
</param-value > </init-param > <load-on-startup > 1
</load-on-startup > </servlet > <servlet-mapping > <servlet-name > mvc
</servlet-name > <url-pattern > *.do
</url-pattern > </servlet-mapping >
</web-app >
配置HandlerMapping/HandlerAdapter(mvc-servlet.xml) <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns ="http://www.springframework.org/schema/beans" xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation ="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsd" > <bean class ="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping" /> <bean class ="org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter" />
</beans >
/*** @author jifang* @since 16/3/15 下午4:40.*/
public class UserController implements Controller {@Override public ModelAndView
handleRequest (HttpServletRequest request, HttpServletResponse response)
throws Exception {List<User> users =
new ArrayList<>();users.add(
new User(
1 ,
"翡青" ,
new Date(),
1 ,
"浙江-杭州" ));users.add(
new User(
2 ,
"小芳" ,
new Date(),
2 ,
"山東-青島" ));ModelAndView result =
new ModelAndView();result.addObject(
"users" , users);result.setViewName(
"users" );
return result;}
}
<bean name ="/mvc/users.do" class ="com.fq.mvc.controller.UserController" />
配置ViewResolver(mvc-servlet.xml) Velocity ,因此配置VelocityViewResolver: <bean id ="viewResolver" class ="org.springframework.web.servlet.view.velocity.VelocityViewResolver" > <property name ="suffix" value =".vm" /> <property name ="contentType" value ="text/html;charset=UTF-8" /> <property name ="dateToolAttribute" value ="dateTool" /> <property name ="numberToolAttribute" value ="numberTool" /> <property name ="exposeRequestAttributes" value ="false" /> <property name ="exposeSessionAttributes" value ="true" />
</bean >
<bean id ="velocityConfigurer" class ="org.springframework.web.servlet.view.velocity.VelocityConfigurer" > <property name ="resourceLoaderPath" value ="views" /> <property name ="velocityProperties" > <props > <prop key ="input.encoding" > UTF-8
</prop > <prop key ="output.encoding" > UTF-8
</prop > </props > </property >
</bean >
<html >
<head > <title > 用戶列表
</title > <link rel ="stylesheet" href ="/css/main.css" > <meta http-equiv ="content-type" content ="text/html; charset=UTF-8" />
</head >
<body >
<div id ="global" > <fieldset > <legend > 用戶列表:
</legend > <table width ="100%" border =0 > <tr > <td > ID
</td > <td > username
</td > <td > birthday
</td > <td > sex
</td > <td > address
</td > </tr > #foreach($user in $users)
<tr > <td > ${user.id}
</td > <td > ${user.name}
</td > <td > ${user.birthday}
</td > #if(${user.sex} == 1)
<td > 男
</td > #else
<td > 女
</td > #end
<td > ${user.address}
</td > </tr > #end
</table > </fieldset >
</div >
</body >
</html >
參考: main.css地址:OSChina
小結(jié)
前端控制器
*.do: 攔截所有以.do結(jié)尾的URI. / : 攔截 所有 URI. 處理器映射器
處理器適配器
視圖解析器 Velocity 作為視圖展示,如果使用的是JSP的話, 需要配置另一種視圖解析器InternalResourceViewResolver:
<bean class ="org.springframework.web.servlet.view.InternalResourceViewResolver" > <property name ="viewClass" value ="org.springframework.web.servlet.view.JstlView" /> <property name ="prefix" value ="/views" /> <property name ="suffix" value =".jsp" />
</bean >
注解初步
從2.5版本開始, Spring引入了注解開發(fā):
注解驅(qū)動(mvc-servlet.xml) 從3.1版本開始,Spring MVC使用RequestMappingHandlerMapping 注解式處理器映射器 對標(biāo)有@ResquestMapping的方法進(jìn)行映射 . 從3.1版本開始,Spring MVC使用RequestMappingHandlerAdapter 注解式處理器適配器 對標(biāo)記有@ResquestMapping的方法進(jìn)行適配 . Spring MVC使用<mvc:annotation-driven/> 注解驅(qū)動 自動加載RequestMappingHandlerMapping和RequestMappingHandlerAdapter及其他相關(guān)配置. 因此在mvc-servlet.xml最簡單有效的配置方式是使用<mvc:annotation-driven/>替代注解處理器和適配器: <mvc:annotation-driven />
盡管<mvc:annotation-driven/>很小, 但他具有足夠的威力, 它注冊了很多的特性, 包括對JSR-303校驗、信息轉(zhuǎn)換以及對域格式化的支持.
組件掃描(mvc-servlet.xml):
<
context :
component -scan base-
package =
"com.fq.mvc.controller" />
@Controller
@RequestMapping (
"/mvc" )
public class UserController {@RequestMapping (
"/users.do" )
public ModelAndView
users () {List<User> users =
new ArrayList<>();users.add(
new User(
1 ,
"翡青" ,
new Date(),
1 ,
"浙江-杭州" ));users.add(
new User(
2 ,
"小芳" ,
new Date(),
2 ,
"山東-青島" ));ModelAndView result =
new ModelAndView();result.addObject(
"users" , users);result.setViewName(
"users" );
return result;}
}
使用基于注解的`Controller`有以下優(yōu)點:- 基于注解的`Controller`請求映射關(guān)系不存儲在配置文件中,使用`@RequestMappeing`便可以對一個方法進(jìn)行映射.- 一個`Controller`內(nèi)可以有多個處理方法,可以響應(yīng)多個動作,這樣就允許將同一模塊的多個操作寫在同一個`Controller`里面,便于模塊劃分,且減少類的數(shù)量.
集成MyBatis
通過Spring將各層整合: 持久層DAO(MyBatis的Mapper)注冊到Spring容器中. 業(yè)務(wù)層Service/Manager從Spring容器中拿到DAO接口, 并注冊Service服務(wù). 表現(xiàn)層Controller從Spring容器中拿到Service接口, 通過Spring MVC進(jìn)行數(shù)據(jù)展示.
需求: 展示所有用戶數(shù)據(jù)(由于數(shù)據(jù)模型較簡單, 因此從DAO到Controller只使用一個DO對象-User).
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-core
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-context
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-context-support
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-beans
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-expression
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-web
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-test
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-aop
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-aspects
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > javax.servlet
</groupId > <artifactId > javax.servlet-api
</artifactId > <version > ${servlet.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-webmvc
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.apache.velocity
</groupId > <artifactId > velocity
</artifactId > <version > ${velocity.version}
</version >
</dependency >
<dependency > <groupId > org.apache.velocity
</groupId > <artifactId > velocity-tools
</artifactId > <version > ${velocity.tools.version}
</version >
</dependency >
<dependency > <groupId > org.mybatis
</groupId > <artifactId > mybatis
</artifactId > <version > 3.3.0
</version >
</dependency >
<dependency > <groupId > mysql
</groupId > <artifactId > mysql-connector-java
</artifactId > <version > ${mysql.version}
</version >
</dependency >
<dependency > <groupId > com.zaxxer
</groupId > <artifactId > HikariCP
</artifactId > <version > ${hikaricp.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-jdbc
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.springframework
</groupId > <artifactId > spring-tx
</artifactId > <version > ${spring.version}
</version >
</dependency >
<dependency > <groupId > org.mybatis
</groupId > <artifactId > mybatis-spring
</artifactId > <version > ${mybatis.spring.version}
</version >
</dependency >
<dependency > <groupId > ch.qos.logback
</groupId > <artifactId > logback-classic
</artifactId > <version > ${logback.version}
</version >
</dependency >
集成MyBatis
mybatis-configuration.xml <?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN""http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration > <mappers > <mapper resource ="mybatis/mapper/UserDAO.xml" /> </mappers >
</configuration >
/*** @author jifang.* @since 2016/5/26 11:16.*/
public class User {private int id;
private String name;
private Date birthday;
private int sex;
private String address;
public User () {}
public User (
int id, String name, Date birthday,
int sex, String address) {
this .id = id;
this .name = name;
this .birthday = birthday;
this .sex = sex;
this .address = address;}
public int getId () {
return id;}
public void setId (
int id) {
this .id = id;}
public String
getName () {
return name;}
public void setName (String name) {
this .name = name;}
public Date
getBirthday () {
return birthday;}
public void setBirthday (Date birthday) {
this .birthday = birthday;}
public int getSex () {
return sex;}
public void setSex (
int sex) {
this .sex = sex;}
public String
getAddress () {
return address;}
public void setAddress (String address) {
this .address = address;}
}
/*** @author jifang* @since 16/3/20 下午5:47.*/
public interface UserDAO {List<User> selectAllUsers();
}
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN""http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace ="com.fq.mvc.dao.UserDAO" > <select id ="selectAllUsers" resultType ="com.fq.mvc.domain.User" > SELECT *FROM user;
</select > </mapper >
applicationContext-datasource.xml(配置數(shù)據(jù)源) <beans xmlns ="http://www.springframework.org/schema/beans" xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance" xmlns:context ="http://www.springframework.org/schema/context" xsi:schemaLocation ="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsd" > <context:property-placeholder location ="classpath:db.properties" /> <bean id ="hikariConfig" class ="com.zaxxer.hikari.HikariConfig" > <property name ="driverClassName" value ="${mysql.driver.class}" /> <property name ="jdbcUrl" value ="${mysql.url}" /> <property name ="username" value ="${mysql.user}" /> <property name ="password" value ="${mysql.password}" /> <property name ="maximumPoolSize" value ="5" /> <property name ="maxLifetime" value ="700000" /> <property name ="idleTimeout" value ="600000" /> <property name ="connectionTimeout" value ="10000" /> <property name ="dataSourceProperties" > <props > <prop key ="dataSourceClassName" > com.mysql.jdbc.jdbc2.optional.MysqlDataSource
</prop > <prop key ="cachePrepStmts" > true
</prop > <prop key ="prepStmtCacheSize" > 250
</prop > <prop key ="prepStmtCacheSqlLimit" > 2048
</prop > </props > </property > </bean > <bean id ="dataSource" class ="com.zaxxer.hikari.HikariDataSource" destroy-method ="close" > <constructor-arg ref ="hikariConfig" /> </bean > <bean id ="sqlSessionFactory" class ="org.mybatis.spring.SqlSessionFactoryBean" > <property name ="dataSource" ref ="dataSource" /> <property name ="configLocation" value ="classpath:mybatis/mybatis-configuration.xml" /> </bean > <bean class ="org.mybatis.spring.mapper.MapperScannerConfigurer" > <property name ="basePackage" value ="com.fq.mvc.dao" /> <property name ="sqlSessionFactoryBeanName" value ="sqlSessionFactory" /> </bean > <bean id ="transactionManager" class ="org.springframework.jdbc.datasource.DataSourceTransactionManager" > <property name ="dataSource" ref ="dataSource" /> </bean > </beans >
## Data Source
mysql
.driver .class =
com .mysql .jdbc .Driver
mysql
.url =jdbc:mysql://host:port/db?characterEncoding=utf-
8
mysql
.user =user
mysql
.password =password
集成Service
public interface UserService {List<User> getAllUsers();
}
@Service
public class UserServiceImpl implements UserService {@Autowired private UserDAO dao;
@Override public List<User>
getAllUsers () {
return dao.selectAllUsers();}
}
applicationContext.xml(配置組件掃描與事務(wù)控制) <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns ="http://www.springframework.org/schema/beans" xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance" xmlns:context ="http://www.springframework.org/schema/context" xmlns:tx ="http://www.springframework.org/schema/tx" xmlns:aop ="http://www.springframework.org/schema/aop" xsi:schemaLocation ="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.springframework.org/schema/aophttp://www.springframework.org/schema/aop/spring-aop.xsd" > <import resource ="applicationContext-datasource.xml" /> <context:component-scan base-package ="com.fq.mvc.service" /> <bean id ="transactionManager" class ="org.springframework.jdbc.datasource.DataSourceTransactionManager" > <property name ="dataSource" ref ="dataSource" /> </bean > <tx:advice id ="txAdvice" transaction-manager ="transactionManager" > <tx:attributes > <tx:method name ="select*" timeout ="-1" propagation ="REQUIRED" read-only ="true" /> </tx:attributes > </tx:advice > <aop:config > <aop:advisor advice-ref ="txAdvice" pointcut ="execution(* com.fq.mvc.service.impl.UserServiceImpl.*(..))" /> </aop:config > </beans >
集成MVC
@Controller
@RequestMapping (
"/mvc" )
public class UserController {@Autowired private UserService service;
@RequestMapping (value =
"/user.do" )
public ModelAndView
users () {List<User> users = service.getAllUsers();
return new ModelAndView(
"users" ,
"users" , users);}
}
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns ="http://www.springframework.org/schema/beans" xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc ="http://www.springframework.org/schema/mvc" xmlns:context ="http://www.springframework.org/schema/context" xsi:schemaLocation ="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/mvchttp://www.springframework.org/schema/mvc/spring-mvc.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsd" > <mvc:annotation-driven /> <context:component-scan base-package ="com.fq.mvc.controller" /> <bean id ="viewResolver" class ="org.springframework.web.servlet.view.velocity.VelocityViewResolver" > <property name ="suffix" value =".vm" /> <property name ="contentType" value ="text/html;charset=UTF-8" /> <property name ="dateToolAttribute" value ="dateTool" /> <property name ="numberToolAttribute" value ="numberTool" /> <property name ="exposeRequestAttributes" value ="false" /> <property name ="exposeSessionAttributes" value ="true" /> </bean > <bean id ="velocityConfigurer" class ="org.springframework.web.servlet.view.velocity.VelocityConfigurer" > <property name ="resourceLoaderPath" value ="views" /> <property name ="velocityProperties" > <props > <prop key ="input.encoding" > UTF-8
</prop > <prop key ="output.encoding" > UTF-8
</prop > </props > </property > </bean >
</beans >
<?xml version="1.0" encoding="UTF-8"?>
<web-app version ="3.0" xmlns ="http://java.sun.com/xml/ns/javaee" xmlns:xsi ="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation ="http://java.sun.com/xml/ns/javaeehttp://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" > <display-name > MVC
</display-name > <listener > <listener-class > org.springframework.web.context.ContextLoaderListener
</listener-class > </listener > <context-param > <param-name > contextConfigLocation
</param-name > <param-value > classpath:spring/applicationContext.xml
</param-value > </context-param > <servlet > <servlet-name > mvc
</servlet-name > <servlet-class > org.springframework.web.servlet.DispatcherServlet
</servlet-class > <init-param > <param-name > contextConfigLocation
</param-name > <param-value > classpath:spring/mvc-servlet.xml
</param-value > </init-param > <load-on-startup > 1
</load-on-startup > </servlet > <servlet-mapping > <servlet-name > mvc
</servlet-name > <url-pattern > *.do
</url-pattern > </servlet-mapping >
</web-app >
集成log
為了能夠看到Spring MVC的運行時信息 , 最好在應(yīng)用中集成一種Log實現(xiàn), 在此選用LogBack :
<configuration > <property name ="log_root_dir" value ="/data/logs/mvc/" /> <property name ="log_pattern" value ="%d{HH:mm:ss.SSS} [%thread] %-5level %logger{0} - %msg%n" /> <appender name ="STD_OUT" class ="ch.qos.logback.core.ConsoleAppender" > <encoder > <pattern > ${log_pattern}
</pattern > </encoder > </appender > <appender name ="FILE_OUT" class ="ch.qos.logback.core.rolling.RollingFileAppender" > <rollingPolicy class ="ch.qos.logback.core.rolling.TimeBasedRollingPolicy" > <fileNamePattern > ${log_root_dir}/mvc-server.%d{YY-MM-dd}.log
</fileNamePattern > <maxHistory > 7
</maxHistory > </rollingPolicy > <encoder > <pattern > ${log_pattern}
</pattern > </encoder > </appender > <root level ="DEBUG" > <appender-ref ref ="STD_OUT" /> <appender-ref ref ="FILE_OUT" /> </root > </configuration >
注解開發(fā)
需求: 實現(xiàn)User添加.
<html >
<head > <title > 用戶添加
</title > <link rel ="stylesheet" href ="/css/main.css" > <meta http-equiv ="content-type" content ="text/html; charset=UTF-8" />
</head >
<body >
<div id ="global" > <fieldset > <legend > Add a User
</legend > <form action ="/mvc/add_user.do" method ="post" > <p > <label for ="name" > username:
</label > <input type ="text" name ="name" tabindex ="1" > </p > <p > <label for ="birthday" > birthday:
</label > <input type ="text" name ="birthday" tabindex ="2" /> </p > <p > <label for ="sex" > sex:
</label > <select name ="sex" tabindex ="3" > <option value ="1" > 男
</option > <option value ="2" > 女
</option > </select > </p > <p > <label form ="address" > address:
</label > <input type ="text" name ="address" tabindex ="4" > </p > <p id ="buttons" > <input type ="reset" tabindex ="5" > <input type ="submit" tabindex ="6" value ="Add User" > </p > </form > </fieldset >
</div >
</body >
</html >
@RequestMapping (
"/add_user.do" )
public String
addUser (User user){service.addUser(user);
return "redirect: users.do" ;
}
Service/DAO實現(xiàn)簡單,不再贅述. 請求參數(shù)解析
在傳統(tǒng)的Servlet編程中, 可以使用HttpServletRequest的getParameter()方法來獲取請求參數(shù)值, 而在Spring MVC中, 它會調(diào)用請求參數(shù)解析組件 將客戶端傳過來的String字符串 解析為指定的Java對象 并傳遞給Controller, 這個過程稱為請求參數(shù)解析 .
Spring MVC默認(rèn)提供了很多參數(shù)解析組件 , 因此Controller的請求處理方法默認(rèn)就可以接收很多不同類型:
JavaEEJavaSESpring ServletRequest / HttpServletRequest InputStream / Reader WebRequest / NativeWebRequest ServletResponse / HttpServletResponse OutputStream / Writer Model / ModelMap HttpSession 命令或表單對象 (如String / Integer / User) RedirectAttributes HttpEntity<?> Array / List / Map Errors / BindingResult 帶@PathVariable / @MatrixVariable注解的對象 @RequestParam / @RequestHeader / @RequestBody / @RequestPart Principal / Locale SessionStatus UriComponentsBuilder
注: 路徑變量映射 (路徑變量類似于請求參數(shù), 但沒有key部分, 只是一個值, 詳細(xì)可參考博客Spring MVC URL 路徑映射).
ModelAttribute
Spring MVC會在每次調(diào)用請求處理方法時都創(chuàng)建一個Model對象, 若打算使用該實例, 則可以在方法的形參添加一個Model形參. 其實還可以使用@ModelAttribute注解來訪問Model實例: 使用@ModelAttribute注解標(biāo)注參數(shù)或方法,該方法會將其輸入的或創(chuàng)建的參數(shù)對象添加到Model對象中:
@ModelAttribute標(biāo)注形參 @RequestMapping (
"/check_id.do" )
public String
checkId (@
ModelAttribute ("id") String id, Model model){
return "check_id" ;
}
String實例將以id做key添加到Model對象中(如果key未命名,則默認(rèn)使用類型的名稱(如string)做key).
@ModelAttribute標(biāo)注方法 非請求處理方法 : 被@ModelAttribute標(biāo)注的方法會在每次調(diào)用Controller的請求處理方法時調(diào)用.該方法可以返回對象或void: 如果返回對象, 該對象會自動添加到Model中:
@ModelAttribute
private List<User>
addUser () {
return service.getAllUsers();
}
若返回void, 則必須添加一個Model類型參數(shù), 自行將實例添加到Model中:
@ModelAttribute
private void addUser (Model model) {model.addAttribute(
"users" , service.getAllUsers());
}
重定向與Flash屬性
使用重定向的一個重要場景是避免用戶重新加載頁面再次調(diào)用相同動作 . 比如add_user.do: 當(dāng)用戶提交表單時會將用戶信息插入數(shù)據(jù)庫. 但如果在提交表單后重新加載頁面, add_user.do會被再次調(diào)用, 相同的用戶可能會被再次添加.為了避免這種情況, 最好的辦法是在提交表單后將用戶重定向到一個不同的頁面,這個頁面任意重新加載都沒有副作用.
但使用重定向的一個不便之處在于: 無法輕松的給目標(biāo)頁面?zhèn)髦?/strong>. 如果采用轉(zhuǎn)發(fā), 可屬性添加到Model, 使得目標(biāo)視圖可以輕松訪問. 但用戶重定向需要經(jīng)過客戶端, 所以Model的一切內(nèi)容都會在重定向中丟失. 幸運的是, 在Spring 3.1之后,可以通過Flash屬性提供重定向傳值的方法:
要使用Flash屬性, 必須要有<annotation-driven/>注解驅(qū)動支持, 然后在方法上添加一個新的參數(shù)類型RedirectAttributes:
@RequestMapping (
"/add_user.do" )
public String
addUser (User user, RedirectAttributes attributes){service.addUser(user);attributes.addAttribute(
"message" ,
"new user has been saved to DB." );
return "redirect: /views/message.vm" ;
}
Controller返回值
應(yīng)用了@Controller與@RequestMapping注解之后,Controller不再需要implements特定的接口, 因此Controller的返回值也變得多種多樣:
返回值描述 ModelAndView 包含視圖名與Model數(shù)據(jù) Model Map 包含模型的屬性 View String 代表邏輯視圖名 void 可以在參數(shù)中傳入request/response完成對參數(shù)的解析, 對客戶端的響應(yīng) HttpEntity/ResponseEntity 提供對Servlet的訪問, 以響應(yīng)HTTP頭部和內(nèi)容 Callable DeferredResult 其他任意類型 常與響應(yīng)JSON/XML結(jié)合
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