求助：最简单的json实例，jquery的getJSON获取不到data

getjsontest.jsp部分
 <%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">

    <title>getjson</title>

    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
  <script type="text/javascript" src="jquery.js"></script>
  <script type="text/javascript">
    $(function(){
        //$.getJSON(url,data,success(data,status,xhr));
        $.getJSON("getJsonData.do",function(data,status,xhr){
            alert(data);
            //$("#jsondata").html(data.id+":"+data.text+":"+data.desc);
        });
    });
  </script>
  </head>

  <body>
    <div id="jsondata"></div>
  </body>
</html>

getJsonData.java部分
 package com.iflytek.ajaxtest;

import java.io.IOException;
import java.io.PrintWriter;

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

public class getJsonData extends HttpServlet{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        // TODO Auto-generated method stub
        req.setCharacterEncoding("utf-8");
        resp.setCharacterEncoding("utf-8");
        resp.setContentType("text/html,charset=utf-8");
        PrintWriter pw = resp.getWriter();
        pw.print("JSONObject{\"id\":1,\"text\":\"Java\",\"desc\":\"Write once,run anywhere\"}");
    }
}

$.getJSON(url,[data],[callback])；不应该是三个参数吗？你写三个参数试试
代码代码如下:

$.getJSON("data.php",$("#firstName.val()"),function(jsonData){
$("#getJSONResponse").html(jsonData.id);}//无需设置，直接获取的数据类型为json，
所以调用时需要使用jsonData.id方式

);

这个getJsonData.do的映射是怎么设置的，怎么没有找到呀，你直接在浏览器中访问，看能不能获取相对应的数据

回调函数执行成功，应该是你Json字符串的问题
pw.print("JSONObject{\"id\":1,\"text\":\"Java\",\"desc\":\"Write once,run anywhere\"}");
你没有创建json对象，这是一个字符串