Java中的物件與Json字串互轉

• 物件、List、Map轉Json字串：JSONObject.toJSONString（）；

• Json字串轉物件：JSONObject.parseObject(userStr,XXX.class)；

• Json字串轉List：JSONArray.parseArray(arrayStr,XXX.class)；

• Json字串轉Map：JSONObject.parseObject(mapStr,Map.class)；

User類

 1 package com.serialization;
 2 
 3 import lombok.Data;
 4
 
 import lombok.ToString;
 5 
 6 @Data
 7 @ToString
 8 public class User {
 9     /**
10      * 使用者ID
11      */
12     private String userId;
13     /**
14      * 使用者名稱稱
15      */
16     private String userName;
17     /**
18      * 使用者年齡
19      */
20     private Integer age;
21 }

MainApp類

 1 public class
 
 MainApp {
 2     public static void main(String[] args) {
 3         User user = new User();
 4         user.setUserId("1001");
 5         user.setUserName("YoYo");
 6         user.setAge(1000);
 7         //物件轉Json字元傳
 8         String userJson=JSONObject.toJSONString(user);
 9         System.out.println("Object to Json: " + userJson);
 
10 
11         //List轉Json字串
12         List<User> list=new ArrayList<>();
13         list.add(user);
14         String userListJson= JSONObject.toJSONString(list);
15         System.out.println("List to Json: "+userListJson);
16 
17         //Map轉Json字串
18         Map<String,Object> map=new HashMap<>();
19         map.put("name","YOYO");
20         map.put("type","CAR");
21         String mapJson=JSONObject.toJSONString(map);
22         System.out.println("Map to Json: "+mapJson);
23 
24         String userStr="{\"age\":1000,\"userId\":\"1001\",\"userName\":\"YoYo\"}";
25         //物件Json字串轉物件
26         User user1=JSONObject.parseObject(userStr,User.class);
27         System.out.println("Json(Object) to Object: "+user1);
28 
29         //List Json字串轉List
30         String arrayStr="[{\"age\":1000,\"userId\":\"1001\",\"userName\":\"YoYo\"}]";
31         List<User> list1= JSONArray.parseArray(arrayStr,User.class);
32         System.out.println("Json(List) to List: "+list1);
33 
34         //Map Json字串轉Map
35         String mapStr="{\"name\":\"YOYO\",\"type\":\"CAR\"}";
36         Map<String,String>map1=JSONObject.parseObject(mapStr,Map.class);
37         System.out.println("Json(Map) to List: "+map1);
38     }
39 }

執行結果

Object to Json: {"age":1000,"userId":"1001","userName":"YoYo"}
List to Json: [{"age":1000,"userId":"1001","userName":"YoYo"}]
Map to Json: {"name":"YOYO","type":"CAR"}
Json(Object) to Object: User(userId=1001, userName=YoYo, age=1000)
Json(List) to List: [User(userId=1001, userName=YoYo, age=1000)]
Json(Map) to List: {name=YOYO, type=CAR}