java转换json的方式
1.引言
2.对象json转换通常常用Map参数形式，优点是1.属性有key,js前端可以清晰从后台key解析出来 2.MAP参数方便添加其他集合如List即包含可能其他集合的信息,承载的信息可以是多种组合方式.。
如 Map map=new HashMap();
map.put("id",1);
map.name("name"，"张三");
String result=JSONObject.fromObject(map1).toString();
输出结果是
{"id":1,"name":"张三"}
前台页面取值
$.ajax({
cache:false,
type:'post',
async:false,
height:350,
url:'<%=path%>/jsonServlet',
dataType: 'json',
timeout: 1000,
data:{"txtName":txtName},
success: function(data){
var obj = eval(data);
alert(obj.id); //这里取的是键id
$.each(obj,function(i,n){ //循坏开始
alert(n);
});
},
error: function(XMLHttpRequest, textStatus, errorThrown){
//alert(XMLHttpRequest.status);
return false;
}
});
});
js前台取值如下
下面我们在往Map添加一个List,下面模拟输入模糊查询张
request.setCharacterEncoding("utf-8");
response.setContentType("text/json;charset=utf-8");
response.setCharacterEncoding("utf-8");
String txtName = request.getParameter("txtName"); // 获取查询姓名
String personList[] = { "张三", "张一", "张二", "张三", "张四", "张五" }; // 人员信息列表
List list = new ArrayList();
Map map = new HashMap();
int coutnNum = 0;
if (!txtName.isEmpty()) {
txtName = txtName.substring(0, 1);
map.put("id", ++coutnNum);
for (String person : personList) {
if (txtName.equals(person.substring(0, 1))) {
list.add(person);
}
}
map.put("list", list);
}
JSONObject json = JSONObject.fromObject(map);
String result = json.toString();
输出结果是{"id":1,"list":["张三","张一","张二","张三","张四","张五"]}
前台页面取值的方式取list的
var obj = eval(data);
var list=obj.list;
$.each(list,function(i,n){ //循坏开始
alert(n);
});
3.完整列子如下
前台页面
<%@ 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>
<meta content="text/html; charset=utf-8" http-equiv=Content-Type>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<script type="text/javascript" src="common/js/jquery-1.4.2.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$("#frm1").click(function (){
var txtName=$("#txtName").val();
//txtName=encodeURI(encodeURI(txtName));
// alert(txtName);
$.ajax({
cache:false,
type:'post',
async:false,
height:350,
url:'<%=path%>/jsonServlet',
dataType: 'json',
timeout: 1000,
data:{"txtName":txtName},
success: function(data){
var obj = eval(data);
var list=obj.list;
$.each(list,function(i,n){ //循坏开始
alert(n);
});
},
error: function(XMLHttpRequest, textStatus, errorThrown){
//alert(XMLHttpRequest.status);
return false;
}
});
});
});
</script>
</head>
<body>
<input type="text" id="txtName" name="txtName"/>
<input type="button" id="frm1" value="提交"/>
<textarea rows="10" cols="50">
</textarea>
</body>
</html>
4.后台java
package com.test;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import net.sf.json.JSONArray;
import net.sf.json.JSONObject;
public class JsonServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/json;charset=utf-8");
response.setCharacterEncoding("utf-8");
String txtName = request.getParameter("txtName"); // 获取查询姓名
String personList[] = { "张三", "张一", "张二", "张三", "张四", "张五" }; // 人员信息列表
JSONArray jsonArray = new JSONArray();
List list = new ArrayList();
Map map = new HashMap();
int coutnNum = 0;
if (!txtName.isEmpty()) {
txtName = txtName.substring(0, 1);
map.put("id", ++coutnNum);
for (String person : personList) {
if (txtName.equals(person.substring(0, 1))) {
list.add(person);
}
}
map.put("list", list);
}
JSONObject json = JSONObject.fromObject(map);
String result = json.toString();
PrintWriter out = response.getWriter();
out.println(result);
out.flush();
out.close();
}
public void init() throws ServletException {
// Put your code here
}
}