ResponseEntity往前台返回JSON

pom.xml

<dependency>
  <groupId>com.alibaba</groupId>
  <artifactId>fastjson</artifactId>
  <version>1.2.6</version>
</dependency>

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/javaee   
    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd">
  <display-name>springmvc</display-name>
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  <!-- 核心控制器 -->
  <servlet>
    <servlet-name>spring</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>/WEB-INF/classes/spring-servlet.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>spring</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:spring-servlet.xml</param-value>
  </context-param>
</web-app>

spring-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"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:context="http://www.springframework.org/schema/context"
       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/mvc http://www.springframework.org/schema/mvc/spring-mvc-3.2.xsd">
    <!-- 配置spring MVC的注解 驱动,激活@Controller模式 -->
    <mvc:annotation-driven />
    <context:component-scan base-package="com.it.controller" />
    <!-- 对转向页面的路径解析。prefix：ji1缀， suffix：后缀 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" />
</beans>

TestController

package com.it.controller;
import com.alibaba.fastjson.JSONObject;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.http.HttpHeaders; 
import org.springframework.http.MediaType;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import java.nio.charset.Charset;
/**
 * Created by Administrator on 2015/12/30.
 */
@Controller
@RequestMapping("/")
public class TestController {
  protected HttpHeaders httpHeaders = new HttpHeaders();
  public TestController() {
    MediaType mediaType = new MediaType("text", "html", Charset.forName("UTF-8"));
    httpHeaders.setContentType(mediaType);
  }
  
  @RequestMapping("/testAjax")
  public ResponseEntity<String> testAjax(){
    JSONObject result = new JSONObject();
    
    result.put("test","test");
    
    return new ResponseEntity<String>(result.toJSONString(), httpHeaders, HttpStatus.OK);
  }  
  
}