JSON
1.json是什么？
*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！单引号不行！！！
>属性值：
*null
*数值
*数组，使用[]括起来
*对象
*字符串
*boolean值
3.应用json
*var person={"name":"zhangsan","password":"961012gz","age":12};
函数eval()：
将字符串当成js代码执行，一般格式为： eval("("+str+")");返回的是一个对象
4.json与xml比较
*可读性：xml胜出
*解析难度：json主场优势
*流行度：xml流行很多年
-------------------------------
json-lib
1、是什么？可以将json数据转换成json字符串
2、导入jar包 略
3、核心类
*JSONObject--》Map
>toString()
>JSONObject map=JSONObject.fromObject(person); 把对象转换成JSONObject独享
*JSONArray-->List
>toString
>JSONArray jsonArray=JSONObject.fromObject(list):把list转化成为JSONArray对象
了解json数据的小例子：
<%@ 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>My JSP 'json1.jsp' starting page</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">
window.onload=function(){
//var person={"name":"guozhen","age":12,"sex":"男"};
//alert(person.name+" ,"+person.age+" ,"+person.sex); //var str="{\"name\":\"guozhen\",\"age\":12,\"sex\":\"男\"}";
//var person=eval("("+str+")");
//alert(person.name+" ,"+person.age+" ,"+person.sex); var str="1+2";
var num=eval("("+str+")");
alert(num);
}
</script>
</head> <body>
<h1>json的简单应用！</h1>
</body>
</html>
使用json数据类型进行简单异步刷新：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%
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>My JSP 'json2.jsp' starting page</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">
window.onload=function(){
var btn=document.getElementsByTagName("button")[0];
btn.onclick=function(){
var xmlHttp=createXMLHttpRequest();
xmlHttp.open("GET","<c:url value='/AServlet'/>",true);
xmlHttp.send(null);
xmlHttp.onreadystatechange=function(){
if(xmlHttp.status==200 && xmlHttp.readyState==4){
var text=xmlHttp.responseText;
var person=eval("("+text+")");
var h3=document.getElementsByTagName("h3")[0];
h3.innerHTML="name:"+person.name+",age:"+person.age+",sex:"+person.sex;
}
};
};
}; function createXMLHttpRequest(){
try{
return new XMLHttpRequest();
}catch(e){
try{
return new ActiveXObject("Msxml2.XMLHTTP");
}catch(e){
try{
return new ActiveXObject("Microsoft.XMLHTTP");
}catch(e){
alert("哥们，你用的什么浏览器啊！");
throw e;
}
}
}
}
</script>
</head> <body>
<button>点击我</button>
<h1>JSON之Hello World</h1>
<h3></h3>
</body>
</html>
json2.jsp
package cn.itcast.web.servlet; import java.io.IOException; import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse; public class AServlet extends HttpServlet{ protected void doGet(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, IOException {
String str="{\"name\":\"zhangSan\",\"age\":18,\"sex\":\"male\"}";
resp.getWriter().print(str);
} }
AServlet
使用json-lib的操作例子：
package cn.itcast.demo1; import java.util.ArrayList;
import java.util.List; import net.sf.json.JSONArray;
import net.sf.json.JSONObject; import org.junit.Test; public class Demo1 { /**
* JSONObject
*/
/*
* 当map用
*/
@Test
public void fun1(){
JSONObject map=new JSONObject();
map.put("name", "zhangSan");
map.put("age", 23);
map.put("sex","male"); String s=map.toString();
System.out.println(s);
} /*
* 当你已经有一个Person对象时，可以把Person转成JSONObject对象
*/
@Test
public void fun2(){
Person p=new Person("liSi",32,"male");
//把对象转换成JSONObject类型
JSONObject s=JSONObject.fromObject(p);
System.out.println(s);
} /**
* JSONArray
*/
@Test
public void fun3(){
Person p1=new Person("zhanSan",32,"male");
Person p2=new Person("liSi",23,"women");
JSONArray list=new JSONArray();
list.add(p1);
list.add(p2);
System.out.println(list);
} /*将对象集合转换成为JSONArray*/
@Test
public void fun4(){
Person p1=new Person("zhanSan",32,"male");
Person p2=new Person("liSi",23,"women");
List<Person> li=new ArrayList<Person>();
li.add(p1);
li.add(p2);
System.out.println(JSONArray.fromObject(li));
} public static void main(String[] args) {
Demo1 d=new Demo1();
d.fun4();
} }
Demo1.java
package cn.itcast.demo1;
public class Person {
private String name;
private int age;
private String sex;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Person() {
super();
// TODO Auto-generated constructor stub
}
public Person(String name, int age, String sex) {
super();
this.name = name;
this.age = age;
this.sex = sex;
}
}
Person.java