前言

只有光头才能变强。

文本已收录至我的GitHub仓库，欢迎Star：https://github.com/ZhongFuCheng3y/3y

什么是JSON

JSON：JavaScript Object Notation 【JavaScript 对象表示法】

JSON 是存储和交换文本信息的语法。类似 XML。

JSON采用完全独立于任何程序语言的文本格式，使JSON成为理想的数据交换语言S

为什么需要JSON

提到JSON，我们就应该和XML来进行对比。XML也是一种存储和交换文本信息的手段。那么JSON好在哪里呢？？

JSON 比 XML 更小、更快，更易解析。

更加容易创建JavaScript对象

var p = {'city':['北京','上海','广州','深圳']};for(var i=0;i<p.city.length;i++){    document.write(p.city[i]+"<br/>");}'city':['北京','上海','广州','深圳']};for(var i=0;i<p.city.length;i++){    document.write(p.city[i]+"<br/>");}

JSON语法

客户端与服务端的交互数据无非就是两种

于是乎，JSON所表示的数据要么就是对象，要么就是数组

JSON语法是javaScript语法的子集，javaScript用[]中括号来表示数组，用{}大括号来表示对象，JSON亦是如此

JSON数组：

var employees = [{ "firstName":"Bill" , "lastName":"Gates" },{ "firstName":"George" , "lastName":"Bush" },{ "firstName":"Thomas" , "lastName": "Carter" }];{ "firstName":"Bill" , "lastName":"Gates" },{ "firstName":"George" , "lastName":"Bush" },{ "firstName":"Thomas" , "lastName": "Carter" }];

JSON对象

var obj = {    age: 20,    str: "zhongfucheng",    method: function () {        alert("我爱学习");    }};

    age: 20,    str: "zhongfucheng",    method: function () {        alert("我爱学习");    }

};

当然啦，数组可以包含对象，在对象中也可以包含数组

解析JSON

javaScript原生支持JSON的，我们可以使用eval()函数来解析JSON，把JSON文本数据转换成一个JavaScript对象。

function test() {    //在写JOSN的时候，记得把带上逗号    var txt = "{a:123," +            "b:'zhongfucheng'}";    //使用eval解析JSON字符串，需要增添()    var aa = eval("(" + txt + ")");    alert(aa);}    //在写JOSN的时候，记得把带上逗号    var txt = "{a:123," +            "b:'zhongfucheng'}";

    //使用eval解析JSON字符串，需要增添()    var aa = eval("(" + txt + ")");    alert(aa);

}

效果

不用框架时将JavaBean转成JSON

但是，我们不一定使用框架来做开发呀。因此，我们还得学习使用第三方库来将JavaBean对象、集合转成JSON

导入开发包

事例代码

package cn.itcast.javaee.js.bean2json;import net.sf.json.JSONArray;import java.util.*;/** * 使用第三方工具，将JavaBean对象/List或Set或Map对象转成JSON  * @author AdminTC */public class TestBean2Json {    private static void javabean2json() {        City city = new City(1,"广州");        JSONArray jSONArray = JSONArray.fromObject(city);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        //[{"id":1,"name":"广州"}]    }    private static void list2json() {        List<City> cityList = new ArrayList<City>();        cityList.add(new City(1,"广州"));        cityList.add(new City(2,"珠海"));        JSONArray jSONArray = JSONArray.fromObject(cityList);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        //[{"id":1,"name":"广州"},{"id":2,"name":"珠海"}]    }    private static void set2json() {        Set<City> citySet = new LinkedHashSet<City>();        citySet.add(new City(1,"广州"));        citySet.add(new City(2,"珠海"));        JSONArray jSONArray = JSONArray.fromObject(citySet);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        //[{"id":1,"name":"广州"},{"id":2,"name":"珠海"}]    }    private static void javabeanlist2json() {        List<City> cityList = new ArrayList<City>();        cityList.add(new City(1,"中山"));        cityList.add(new City(2,"佛山"));        Province province = new Province(1,"广东",cityList);        JSONArray jSONArray = JSONArray.fromObject(province);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        /*          [             {              "id":1,              "name":"广东"              "cityList":[{"id":1,"name":"中山"},{"id":2,"name":"佛山"}],             }          ]          */    }    private static void map2json() {        List<City> cityList = new ArrayList<City>();        cityList.add(new City(1,"中山"));        cityList.add(new City(2,"佛山"));        Map<String,Object> map = new LinkedHashMap<String,Object>();        map.put("total",cityList.size());//表示集合的长度        map.put("rows",cityList);//rows表示集合        JSONArray jSONArray = JSONArray.fromObject(map);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        //[{"total":2,"rows":[{"id":1,"name":"中山"},{"id":2,"name":"佛山"}]}]        jsonJAVA = jsonJAVA.substring(1,jsonJAVA.length()-1);        System.out.println(jsonJAVA);    }}

import net.sf.json.JSONArray;

import java.util.*;

/** * 使用第三方工具，将JavaBean对象/List或Set或Map对象转成JSON  * @author AdminTC */public class TestBean2Json {    private static void javabean2json() {        City city = new City(1,"广州");        JSONArray jSONArray = JSONArray.fromObject(city);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        //[{"id":1,"name":"广州"}]    }    private static void list2json() {        List<City> cityList = new ArrayList<City>();        cityList.add(new City(1,"广州"));        cityList.add(new City(2,"珠海"));        JSONArray jSONArray = JSONArray.fromObject(cityList);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        //[{"id":1,"name":"广州"},{"id":2,"name":"珠海"}]    }    private static void set2json() {        Set<City> citySet = new LinkedHashSet<City>();        citySet.add(new City(1,"广州"));        citySet.add(new City(2,"珠海"));        JSONArray jSONArray = JSONArray.fromObject(citySet);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        //[{"id":1,"name":"广州"},{"id":2,"name":"珠海"}]    }    private static void javabeanlist2json() {        List<City> cityList = new ArrayList<City>();        cityList.add(new City(1,"中山"));        cityList.add(new City(2,"佛山"));        Province province = new Province(1,"广东",cityList);

        JSONArray jSONArray = JSONArray.fromObject(province);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        /*          [             {              "id":1,              "name":"广东"              "cityList":[{"id":1,"name":"中山"},{"id":2,"name":"佛山"}],             }          ]          */    }    private static void map2json() {

        List<City> cityList = new ArrayList<City>();        cityList.add(new City(1,"中山"));        cityList.add(new City(2,"佛山"));

        Map<String,Object> map = new LinkedHashMap<String,Object>();        map.put("total",cityList.size());//表示集合的长度        map.put("rows",cityList);//rows表示集合

        JSONArray jSONArray = JSONArray.fromObject(map);        String jsonJAVA = jSONArray.toString();        System.out.println(jsonJAVA);        //[{"total":2,"rows":[{"id":1,"name":"中山"},{"id":2,"name":"佛山"}]}]

        jsonJAVA = jsonJAVA.substring(1,jsonJAVA.length()-1);        System.out.println(jsonJAVA);    }

}

把要解析成JSON 的javaBena对象、集合放进下面这段代码即可！

JSONArray jSONArray = JSONArray.fromObject(map);

无论放进去什么，返回的都是数组

总结