JSON应知应会

JSON简介

简介：
JSON（JavaScriptObject Notation）、轻量级数据交换格式、非常适合于服务器与 JavaScript 的交互。

JSON两种格式：

1、对象
对象是一个无序的“‘名称/值’对”集合。一个对象以“{”（左括号）开始，“}”（右括号）结束。每个“名称”后跟一个“:”（冒号）；“‘名称/值’ 对”之间使用“,”（逗号）分隔。

var person = { "name":"huochai", "age":29, "school":{ "name":"diankeyuan", "location":"beijing" }};

2、数组
数组是值（value）的有序集合。一个数组以“[”（左中括号）开始，“]”（右中括号）结束。值之间使用“,”（逗号）分隔。

var students =  
              [  
                     {"sno":"001","name":"jack","age":130},  
                     {"sno":"002","name":"tame","age":120},  
                     {"sno":"003","name":"cule","age":110},  
              ];  

一些JSON实例

        var person = { "name":"huochai", "age":29, "school":{ "name":"diankeyuan", "location":"beijing" }};
        var strJson = '{ "name":"huochai", "age":29, "school":{ "name":"diankeyuan", "location":"beijing" }}';
        var aa = 'abc';
        var bb = ['baidu','taobao'];
        var cc = {'persons': ['zhangsan','lisi']};
        var students =
                [
                    {"sno":"001","name":"jack","age":130},
                    {"sno":"002","name":"tame","age":120},
                    {"sno":"003","name":"cule","age":110},
                ];

        var personOther = JSON.parse(strJson);

        alert(personOther.age);

JSON对象

　　JSON之所以流行，是因为可以把JSON数据结构解析为有用的javascript对象

　　ECMAScript5对解析JSON的行为进行了规范，定义了全局对象JSON

　　JSON对象有两个方法：stringify()和parse()。这两个方法分别用于把JavaScript对象序列化为JSON字符串和把JSON字符串解析为原生JavaScript值

stringify()

var strPerson = JSON.stringify(person);
alert(strPerson);

var strStudents = JSON.stringify(students);
alert(strStudents);

parse()

　　JSON.parse方法用于将JSON字符串转化成对象

var strPerson = JSON.stringify(person);
var personObj = JSON.parse(strPerson);

var strStudents = JSON.stringify(students);
var studentsObj = JSON.parse(strStudents);

对应的java表示：

public class Person {
    public String name;
    public int    age;
    public School school;
}

public class School {
    public String name;
    public String location;
}

利用fastjson将java对象转换成JSON字符串

        Person person = new Person();
        person.name = "huochai";
        person.age = 29;
        person.school = new School();
        person.school.name = "diankeyuan";
        person.school.location = "beijing";


        String strJson = JSON.toJSONString(person);
        System.out.println(strJson);

        Person person2 = new Person();
        person2.name = "huochai2";
        person2.age = 292;
        person2.school = new School();
        person2.school.name = "diankeyuan2";
        person2.school.location = "beijing2";

        List<Person> lst = new ArrayList<Person>();
        lst.add(person);
        lst.add(person2);


        String strJson2 = JSON.toJSONString(lst);
        System.out.println(strJson2);