使用注解的方式重構helloworld應用案例。

1. @RequestMapping注解應用

@RequestMapping可以用在類定義和方法定義上，它標明這個類或方法與哪一個客戶請求對應。實例代碼如下：

@RequestMapping("/day01")public class HelloController {    @RequestMapping("/hello.form")    public String execute() throws Exception {        return "hello";    }}

2. 開啟@RequestMapping注解映射，需要在Spring的xml配置文件進行配置，配置代碼如下：

<mvc:annotation-driven/>

3. @Controller注解應用

推薦使用@Controller注解聲明Controller組件，這樣可以使得Controller定義更加靈活，可以不用實現Controller接口，請求處理的方法也可以靈活定義。代碼如下：

@Controller@RequestMapping("/day01")public class HelloController {    @RequestMapping("/hello.form")    public String execute() throws Exception {        return "hello";    }}

4. 為了使@Controller注解生效，需要在Spring的XML配置文件中開啟組件掃描定義，并指定Controller組件所在包，配置代碼如下：

 <context:component-scan base-package="com.souvc.controller"/>

使用的環境是eclipse ，jdk7.0 ，Tomcat 7.0,導入Spring依賴包。

步驟一：新建一個新工程，工程名為SpringControler，如圖下：

步驟二：增加HelloController類

使用注解的方式，修改HelloController類，代碼如下所示：

package com.souvc.controller;import org.springframework.stereotype.Controller;import org.springframework.web.bind.annotation.RequestMapping;@Controller@RequestMapping("/day01")public class HelloController {    @RequestMapping("/hello.form")    public String execute() throws Exception {        return "hello";    }}

步驟三：spring-mvc.xml的配置

在spring-mvc.xml文件中，開啟@RequestMapping注解映射以及組件掃描，代碼如下所示：

<?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:jdbc="http://www.springframework.org/schema/jdbc"    xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx"    xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:mvc="http://www.springframework.org/schema/mvc"    xsi:schemaLocation="        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd        http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd        http://www.springframework.org/schema/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">         <context:component-scan base-package="com.souvc.controller"/>        <mvc:annotation-driven/>        <!-- 定義視圖解析器ViewResolver -->    <bean id="viewResolver"        class="org.springframework.web.servlet.view.InternalResourceViewResolver">        <property name="prefix" value="/WEB-INF/jsp/" />        <property name="suffix" value=".jsp" />    </bean></beans>

web.xml文件如下：

<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" 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/javaee     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">    <servlet>        <servlet-name>springmvc</servlet-name>        <servlet-class>            org.springframework.web.servlet.DispatcherServlet        </servlet-class>        <!-- 指定Spring的配置文件 -->        <init-param>            <param-name>contextConfigLocation</param-name>            <param-value>classpath:spring-mvc.xml</param-value>        </init-param>        <load-on-startup>1</load-on-startup>    </servlet>    <servlet-mapping>        <servlet-name>springmvc</servlet-name>        <url-pattern>*.form</url-pattern>    </servlet-mapping>    <welcome-file-list>        <welcome-file>index.jsp</welcome-file>    </welcome-file-list></web-app>

步驟四：測試

通過地址“http://localhost:8080/SpringControler/day01/hello.form”訪問HelloController：