JAVA:

import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

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

import net.sf.json.JSONArray;

public class JSONServlet extends HttpServlet {

    private static final long serialVersionUID = 1L;

    public JSONServlet() {
        super();
    }

    public void destroy() {
        super.destroy(); 
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doPost(request, response);
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        //使用JSONArray测试
        JSONArray jsonArray = new JSONArray();
        jsonArray.add("MCA");
        jsonArray.add("kevin");
        jsonArray.add("15-12-1998");
        jsonArray.add(new Double(12.3));
        List<String> list = new ArrayList<String>(); 
        list.add("a collection added");
        list.add("kevin collection test");
        jsonArray.addAll(list);

        //页面输出JSONArray的内容
        PrintWriter out = response.getWriter();
        out.print(jsonArray);
        out.println("======================================");
        for(int i=0;i<jsonArray.size();i++){
            out.print(jsonArray.getString(i));
        }
    }

    public void init() throws ServletException {
    }
}

web.xml

<?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>JSONServlet</servlet-name>
    <servlet-class>com.justinmobile.JSONServlet</servlet-class>
  </servlet>

  <servlet-mapping>
    <servlet-name>JSONServlet</servlet-name>
    <url-pattern>*.do</url-pattern>
  </servlet-mapping>
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

访问页面:

http://localhost:8080/Json/test.do

我们得到输出结果：

["MCA","kevin","15-12-1998",12.3,"a collection added","kevin collection test"]====================================== MCAkevin15-12-199812.3a collection addedkevin collection test

使用json请先将需要的jar包导入LIB文件夹

下载：JSON_LIB所需的jar包.zip