json-lib简单处理json和对json的简单介绍

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>

View Code

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