Spring3.0实现REST实例

 关于REST是什么东西，在这里我就不再多说，大家可以去http://blog.csdn.net/pilou5400/archive/2010/12/24/6096861.aspx看看介绍，直接切入主题：

      这是一个rest风格的访问，Spring从3.0开始将全面支持rest。不得不感叹Spring的强悍。

      项目结构：

      第一步永远是配置，使用框架永远都是先有配置，在web.xml中的配置：

<?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/javaee
    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
  <display-name></display-name>
  <context-param>
        <!--rest配置文件的路径，貌似不配置也是加载这个地址，这个地方有点疑问，大家指点指点-->
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/rest-servlet.xml</param-value>
  </context-param>
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  <servlet>
        <!-- 配置一个Servlet，有这个Servlet统一调度页面的请求 -->
    <servlet-name>rest</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <load-on-startup>2</load-on-startup>
  </servlet>
  <servlet-mapping>
        <!-- 映射路径，不要写成了/*那样会拦截所有的访问，连JSP页面都访问不了 -->
    <servlet-name>rest</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>/index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

   第二步：配置rest-servlet.xml这个文件

<?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:jee="http://www.springframework.org/schema/jee"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd"
    default-lazy-init="true">

  <description>Spring公共配置</description>

  <!--检测注解-->
  <context:component-scan base-package="com.liqiu" />
  <bean   class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" />
  <bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter" />
<!-- 注册视图解析器，说白了就是根据返回值指定到某个页面 -->
  <bean id="viewResolver"   class="org.springframework.web.servlet.view.InternalResourceViewResolver">
    <property name="viewClass" value="org.springframework.web.servlet.view.JstlView" />
    <property name="prefix" value="/"></property> <!--页面文件的路径，在根目录下-->
   </bean>
</beans>

 第三步：具体实现类

package com.liqiu.controller;

import java.io.IOException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
@RequestMapping("/simple")
public class SimpleController {
    //映射路径/simple/index当访问这个路径时，执行这个方法
    @RequestMapping("/index")
    public String index(HttpServletRequest request ,HttpServletResponse response){
               //response,request会自动传进来
        request.setAttribute("message", "Hello,This is a example of Spring3 RESTful!");
        return "index.jsp";
    }
    //根据ID获取不同的内容，通过@PathVariable 获得属性
    @RequestMapping(value="/{id}",method=RequestMethod.GET)
    public String get(@PathVariable String id,HttpServletRequest request ,HttpServletResponse response) throws IOException{
        request.setAttribute("message", "Hello,This is a example of Spring3 RESTful!<br/>ID:"+id+"");
        //response.getWriter().write("You put id is : "+id);
        return "index.jsp";
        //return null;
    }
}

   index.jsp页面：

<%@ page language="java" pageEncoding="UTF-8"%>
<html>
  <head>
    <title>Spring3 RESTful</title>
   </head>

  <body>
    ${message}
   </body>
</html>

    在浏览器中输入：http://localhost:8080/SpringREST/simple/index/，就可以看到效果。

    也可以在页面输入不同的参数，获得不同的内容，输入地址：http://localhost:8080/SpringREST/simple/88888，这次执行的就是get方法，通过注解获取ID值，效果：

    关于Spring rest 对于Ajax的支持，其实响应Ajax就是通过response返回一个字符串到页面，既然能获得response对象，那问题就迎刃而解了，我们改造下get方法：

@RequestMapping(value="/{id}",method=RequestMethod.GET)
    public String get(@PathVariable String id,HttpServletRequest request ,HttpServletResponse response) throws IOException{
        //request.setAttribute("message", "Hello,This is a example of Spring3 RESTful!<br/>ID:"+id+"");
        response.getWriter().write("You put id is : "+id);
        //return "index.jsp";
        return null;
    }

    改造index.jsp页面：

<%@ page language="java" pageEncoding="UTF-8"%>
<html>
  <head>
    <title>Spring3 RESTful</title>
    <SCRIPT TYPE="text/javascript">
            function go(value){
                var url = "/SpringREST/simple/"+value+"/";
                var request =  new XMLHttpRequest();
                request.open("GET", url, true);
                request.setRequestHeader("Content-Type","application/x-javascript;");
                request.onreadystatechange = function() {
                    if (request.readyState == 4) {
                        if (request.status == 200){
                            if (request.responseText) {
                                document.getElementById("text").innerHTML = request.responseText;
                            }
                        }
                    }
                };
                request.send(null);
            }
        </SCRIPT>
  </head>

  <body>
    ${message}
    <br>
    Input the id of you will access object:<input id="id" type="text" size="7"><input type="button" value="Go" onclick="go(document.getElementById('id').value)">
    <div id="text"></div>
  </body>
</html>

    访问http://localhost:8080/SpringREST/simple/index/，在页面里的输入框中输入值，可以看到返回的数据：