一、JSON
1.JSON是什么
JSON(JavaScript Object Notation) 是一种轻量级的数据交换格式，它是js提供的一种数据交换格式！
2.json的语法
- {}：是对象！
- 属性名必须使用双引号括起来！单引不行！！！
- 属性值：
- null
- 数值
- 字符串
- 数组：使用[]括起来
- boolean值：true和false
3.应用json
- var person = {"name":"zhangSan", "age":18, "sex":"male"};
- alert(person.name+","+person.age+","+person.sex);
4.json与xml比较
- 可读性：XML胜出
- 解析难度：JSON本身就是JS对象（主场作战），所以简单很多
- 流行度：XML已经流行好多年，但在AJAX领域，JSON更受欢迎。
5.示例：
1 package web.servlet; 2 ?3 import javax.servlet.ServletException; 4 import javax.servlet.annotation.WebServlet; 5 import javax.servlet.http.HttpServlet; 6 import javax.servlet.http.HttpServletRequest; 7 import javax.servlet.http.HttpServletResponse; 8 import java.io.IOException; 9 10 @WebServlet(name = "AServlet",urlPatterns = "/AServlet")11 public class AServlet extends HttpServlet {12 ????protected void doGet(HttpServletRequest request, HttpServletResponse response) 13 ????????????throws ServletException, IOException {14 ????????/*15 ????????* 向客户端发送json串16 ????????* */17 ????????String str = "{"name":"zhangsan","age":18,"sex":"male"}";18 ????????response.getWriter().print(str);19 ????????System.out.println(str);20 ????}21 } 1 <%@ page contentType="text/html;charset=UTF-8" language="java" %> 2 <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> 3 <html> 4 <head> 5 ????<title>Title</title> 6 ????<script type="text/javascript"> 7 ????????//创建异步对象 8 ????????function createXMLHttpRequest() { 9 ????????????try {10 ????????????????return new XMLHttpRequest();11 ????????????}catch (e){12 ????????????????try{13 ????????????????????return ActiveXObject("Msxml2.XMLHTTP");14 ????????????????}catch (e){15 ????????????????????try {16 ????????????????????????return ActiveXObject("Microsoft.XMLHTTP");17 ????????????????????}catch (e) {18 ????????????????????????alert("您用的是什么浏览器啊？")19 ????????????????????????throw e;20 ????????????????????}21 ????????????????}22 ????????????}23 ????????}24 ????????window.onload = function () {25 ????????????//获取btn元素26 ????????????var btn = document.getElementById("btn");27 ????????????btn.onclick = function () { //给按钮的点击事件上添加监听28 ????????????????//使用ajax得到服务器端响应，把结果显示到h3中29 ????????????????//1、得到request30 ????????????????var xmlHttp = createXMLHttpRequest();31 ????????????????//2、连接32 ????????????????xmlHttp.open("GET","<c:url value="/AServlet"/>",true);33 ????????????????//3、发送34 ????????????????xmlHttp.send(null);35 ????????????????//4、给xmlHttp的状态改变事件上添加监听36 ????????????????xmlHttp.onreadystatechange =function () {37 ????????????????????//双重判断38 ????????????????????if(xmlHttp.readyState == 4 && xmlHttp.status == 200) {39 ????????????????????????var text = xmlHttp.responseText;//它是一个json串40 ????????????????????????var person = eval("("+text+")");41 ????????????????????????var s = person.name+","+person.age+","+person.sex;42 ????????????????????????document.getElementById("h3").innerHTML = s;43 ????????????????????}44 ????????????????};45 ????????????????46 ????????????};47 ????????};48 ????</script>49 </head>50 <body>51 <%-- 点击按钮后，把服务器响应的数据显示到h3元素中 --%>52 <button id="btn">点击这里</button>53 <h1>JSON之Hello World</h1>54 <h3 id="h3"></h3>55 </body>56 </html>
二、json-lib
1. 是什么？
- 它可以把javabean转换成json串
- json-lib.jar下载链接：https://sourceforge.net/projects/json-lib/files/json-lib/json-lib-2.4/
2. 核心类
- JSONObject --> Map
- toString();
- JSONObject map = JSONObject.fromObject(person)：把对象转换成JSONObject对象
- JSONArray --> List
- toString()
- JSONArray jsonArray = JSONObject.fromObject(list)：把list转换成JSONArray对象
3.示例：
1 package demo1; 2 ?3 import Person.Person; 4 import net.sf.json.JSONArray; 5 import net.sf.json.JSONObject; 6 import org.junit.Test; 7 import java.util.ArrayList; 8 import java.util.List; 9 10 /**11 ?* 演示JSON-lib小工具12 ?*/13 public class Demo1 {14 ????@Test15 ????public void fun1() {16 ????????JSONObject map = new JSONObject();17 ????????map.put("name","zhangsan");18 ????????map.put("age",25);19 ????????map.put("sex","male");20 ????????String s = map.toString();21 ????????System.out.println(s);22 ????}23 ????/*24 ????* 当你已经有一个Person对象时，可以把Person转换成JSONObject对象25 ????*/26 ????@Test27 ????public void fun2() {28 ????????Person p = new Person("lisi",32,"female");29 ????????//把对象转换成JSONObject类型30 ????????JSONObject map = JSONObject.fromObject(p);31 ????????System.out.println(map.toString());32 ????}33 ????/**34 ?????* JSONArray35 ?????*/36 ????@Test37 ????public void fun3() {38 ????????Person p1 = new Person("zhangsan",25,"male");39 ????????Person p2 = new Person("lisi",32,"female");40 41 ????????JSONArray list = new JSONArray();42 ????????list.add(p1);43 ????????list.add(p2);44 45 ????????System.out.println(list.toString());46 ????}47 ????/**48 ?????* 原来就有一个List，我们需要把List转换成JSONArray49 ?????*/50 ????@Test51 ????public void fun4 () {52 ????????Person p1 = new Person("zhangsan",25,"male");53 ????????Person p2 = new Person("lisi",32,"female");54 ????????List<Person> list = new ArrayList<Person>();55 ????????list.add(p1);56 ????????list.add(p2);57 58 ????????System.out.println(JSONArray.fromObject(list).toString());59 ????}60 }JSON
原文地址：https://www.cnblogs.com/gdwkong/p/8191289.html