json例子（后台取消息）

定义一个javascript方法 通过jquery 获取json数据

function search()
  {
      var str="method=search";
      var ctx=document.getElementById("msgList");
    $.ajax(
    {
    type: "post",
    url: "<%=request.getContextPath()%>/msg.do",
    datatype:"json",
    data:str,
    success:function(msg){
    if(msg!=null &&msg!="" && msg!="[null]" && msg!="null")
    {
     var msgobj=eval(msg);
     var tipmessage="";
     for(var i=0;i<msgobj.length;i++)
     {
      var obj=msgobj[i];
      ctx.innerHTML=ctx.innerHTML+"<div id="+obj.id+">"+obj.sendUser+"&nbsp;"+obj.sendTimeStr+"<br/>&nbsp;&nbsp;&nbsp;&nbsp;"+obj.content+"</div><p/>"
      tipmessage=tipmessage+obj.sendUser+"发送一条消息<br/>";
     }
     if(msgobj.length>0){
      tipyou(tipmessage);
      window.focus();
      }
    }
    }});

  }

java 数据对象

package com.qunliao.entity;

import java.util.Date;

import com.qunliao.utils.DateUtils;

public class Msg {
 private String id;
 private Date sendTime;
 private String sendTimeStr;
 private String sendUser;
 private String content;
 private String isGlobel="1";
 private String isRead="0";
 public String getIsRead() {
  return isRead;
 }

 public void setIsRead(String isRead) {
  this.isRead = isRead;
 }

 public String getIsGlobel() {
  return isGlobel;
 }

 public void setIsGlobel(String isGlobel) {
  this.isGlobel = isGlobel;
 }

 public Date getSendTime() {
  return sendTime;
 }

 public void setSendTime(Date sendTime) {
  this.sendTime = sendTime;
 }

 public String getContent() {
  return content;
 }

 public void setContent(String content) {
  this.content = content;
 }

 public String getSendTimeStr() {
  if (sendTime != null)
   return DateUtils.fomart(sendTime);
  return null;
 }

 public String getId() {
  return id;
 }

 public void setId(String id) {
  this.id = id;
 }

 public void setSendTimeStr(String sendTimeStr) {
  this.sendTimeStr = sendTimeStr;
 }

 public String getSendUser() {
  return sendUser;
 }

 public void setSendUser(String sendUser) {
  this.sendUser = sendUser;
 }
}

去后台取数据 的action方法为

public ActionForward search(ActionMapping mapping, ActionForm form,
   HttpServletRequest request, HttpServletResponse response) throws Exception {
  User user=(User)request.getSession().getAttribute("user");
  List list=service.getNonReadMsg(true, user.getId());
  JSONArray array = JSONArray.fromObject(list);
  response.setContentType("text/html; charset=utf-8");
  response.setCharacterEncoding("utf-8");
  response.getWriter().print(array.toString());
  return null;
 }