今天給大家講一個物件、物件集合轉json資料的三種方法，三種方法最終達到的效果是一樣的。

下面就貼出三種寫法的程式碼，讀者可以任選其一去使用。關於demo裡面所使用的jar包，可以自行去下載，也可以加我QQ我給你：1455465841

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<User> lists = new ArrayList<User>();
		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);
		//列印結果
		//[{"password":"111","username":"111"}]
		System.out.println(str2);
		//列印結果
		//[{"password":"111","username":"111"},{"password":"222","username":"222"}]
		
	}
}
 

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<User> lists = new ArrayList<User>();
		lists.add(user1);
		lists.add(user2);
		
		
		Gson gson = new Gson();
		String json1 = gson.toJson(user1);
		System.out.println(json1);
		//列印結果
		//{"username":"111","password":"111"}
		String json2 = gson.toJson(lists);
		System.out.println(json2);
		//列印結果
		//[{"username":"111","password":"111"},{"username":"222","password":"222"}]		
	}
}
 

FastJson：

package json;

import 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、單個物件轉換成json
		String jsonString = JSON.toJSONString(user1);
		System.out.println(jsonString);
		//列印結果
		//{"password":"111","username":"111"}
		
		User user2 = new User();
		user2.setUsername("222");
		user2.setPassword("222");
		List<User> lists = new ArrayList<User>();
		lists.add(user1);
		lists.add(user2);
		String jsonString2 = JSON.toJSONString(lists);
		System.out.println(jsonString2);
		//列印結果
		//[{"password":"111","username":"111"},{"password":"222","username":"222"}]
		
		
	}
}