JAVA编写JSON常用的三种方法

Szx • 2019 年 11 月 15 日

1.jsonlib需要引入的包也多，代码也相对多一些。

2.Gson：谷歌的

3.FastJson：阿里巴巴的，这几个也是性能最好的一个。(推荐)

jsonlib类Jsonlib：package json

import java.util.ArrayList;

import java.util.List;

import net.sf.json.JSONArray;

import user.User;

public class Jsonlib {

public static void main(String[] args) {

User user1 = new User();

user1.setUsername("111");

user1.setPassword("111");

User user2 = new User();

user2.setUsername("222");

user2.setPassword("222");

List lists = new ArrayList();

lists.add(user1);

lists.add(user2);

JSONArray fromObject1 = JSONArray.fromObject(user1);

JSONArray fromObject2 = JSONArray.fromObject(lists);

String str1 = fromObject1.toString();

String str2 = fromObject2.toString();

System.out.println(str1);

//打印结果

//[{"password":"111","username":"111"}]

System.out.println(str2);

//打印结果

//[{"password":"111","username":"111"},{"password":"222","username":"222"}]

}

}

jar包

Gson：package json;

import java.util.ArrayList;

import java.util.List;

import com.google.gson.Gson;

import user.User;

public class Gson_a {

public static void main(String[] args) {

User user1 = new User();

user1.setUsername("111");

user1.setPassword("111");

User user2 = new User();

user2.setUsername("222");

user2.setPassword("222");

List lists = new ArrayList();

lists.add(user1);

lists.add(user2);

Gson gson = new Gson();

String json1 = gson.toJson(user1);

System.out.println(json1);

//打印结果

//{"username":"111","password":"111"}

String json2 = gson.toJson(lists);

System.out.println(json2);

//打印结果

//[{"username":"111","password":"111"},{"username":"222","password":"222"}]

}

}

推荐使用FastJson：

pom依赖

com.alibaba

fastjson

1.2.68

FastJsonTestimport java.util.ArrayList;

import java.util.List;

import com.alibaba.fastjson.JSON;

import user.User;

public class FastJson {

public static void main(String[] args) {

User user1 = new User();

user1.setUsername("111");

user1.setPassword("111");

//1、单个对象转换成json

String jsonString = JSON.toJSONString(user1);

System.out.println(jsonString);

//打印结果

//{"password":"111","username":"111"}

User user2 = new User();

user2.setUsername("222");

user2.setPassword("222");

List lists = new ArrayList();

lists.add(user1);

lists.add(user2);

String jsonString2 = JSON.toJSONString(lists);

System.out.println(jsonString2);

//打印结果

//[{"password":"111","username":"111"},{"password":"222","username":"222"}]

}

}