21.如何将java类对象转化为json字符串

使用阿里巴巴的fastJson

下载链接：

链接: https://pan.baidu.com/s/1dHjLOm1 密码: rr3w

用法如下：

User user = new User();    
user.setAge(18);
user.setUserName("李四");      
String listJson = JSON.toJSONString(user);

 要将一个json对象转化为字符串，只需要toString

 String response = xx
 private JSONObject payInfoJsonObject = new JSONObject(response)；
 String JSONString = payInfoJsonObject.toString();

 获取键值：

package com.scut.emos.util;

/**
 * Created by 蔡木庆 on 2018/2/6.
 */
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
    public class JsonTest {
        public static void main(String args[]){
            String json="{"name":"刘德华","age":35,"some":[{"k1":"v1","k2":"v2"},{"k3":"v3","k4":"v4"}]}";
            //解析一层
            JSONObject test = JSON.parseObject(json);
            System.out.println(test.getString("name"));
            //解析json里面嵌套json
            JSONArray testA = test.getJSONArray("some");
            JSONObject JsonObject0 = testA.getJSONObject(0);
            System.out.println(JsonObject0.getString("k1"));
        }
    }