java与json，一篇就够了

本示例使用的json包为阿里的fastjson

首先写三个工具类（seter和geter方法省略，自行补上）：

1 /**
2  * 屏幕实体类
3  */
4 public class Screen {
5 
6     private String resolution; // 分辨率
7     private String size; // 显存大小
8     
9 }

1 /**
2  * 内存条实体类
3  */
4 public class Memory {
5 
6     private String size; // 大小
7     private String brand; // 品牌
8 
9 }

 1 /**
 2  * 电脑实体类
 3  */
 4 public class Computer {
 5 
 6     private int id; // id
 7     private String brand; // 品牌
 8     private Double price; // 价格
 9     private Screen screen; // 屏幕
10     private List memory; // 内存条
11 
12 }

测试类，直接上代码：

 1 /**
 2  * 测试类
 3  */
 4 public class T01 {
 5 
 6     public static void main(String[] args) {
 7         // 1. 《自定义对象》转《json》
 8         Computer c1 = getComputer();
 9         JSONObject obj = JSONObject.parseObject(JSONObject.toJSONString(c1));
10         System.out.println(obj);
11         System.out.println("---------------------------------------------------------------------------");
12 
13         // 2. 《json》转《自定义对象》
14         String str = obj.toJSONString();
15         Computer c2 = JSONObject.parseObject(str, Computer.class);
16         System.out.println(c2.toString());
17         System.out.println("---------------------------------------------------------------------------");
18 
19         // 3. 《列表》转《JSONArray》
20         List computers = getList();
21         JSONArray ja = JSON.parseObject(JSONArray.toJSONString(computers), JSONArray.class);
22         System.out.println(ja.toJSONString());
23         System.out.println("---------------------------------------------------------------------------");
24 
25         // 4. 《JSONArray》转《列表》
26         List list = JSONArray.parseArray(ja.toJSONString(), Computer.class);
27         list.forEach(System.out::println);
28         System.out.println("---------------------------------------------------------------------------");
29 
30         // 5. 《数组》转《JSONArray》
31         // 用Arrays的asList方法将数组转换成List，然后按照步骤3转换就可以了
32         List ms = Arrays.asList(new Memory[] { new Memory("8G", "金士顿"), new Memory("4G", "三星") });
33         ms.forEach(System.out::println);
34         System.out.println("---------------------------------------------------------------------------");
35 
36         // 6. 《JSONArray》转《数组》
37         Computer[] cs = new Computer[list.size()];
38         list.toArray(cs); // 先按照步骤4将JSONArray转成list，再转成数组
39         for (Computer computer : cs) {
40             System.out.println(computer);
41         }
42     }
43 
44     private static List getList() {
45         List ms1 = Arrays.asList(new Memory[] { new Memory("8G", "金士顿"), new Memory("4G", "三星") });
46         Screen s1 = new Screen("1024*768", "16G");
47         Computer c1 = new Computer(1, "戴尔", 5678.9, s1, ms1);
48 
49         List ms2 = Arrays.asList(new Memory[] { new Memory("16G", "惠普"), new Memory("8G", "森海") });
50         Screen s2 = new Screen("1024*768", "8G");
51         Computer c2 = new Computer(2, "联想", 1234.5, s2, ms2);
52 
53         List ms3 = Arrays.asList(new Memory[] { new Memory("32G", "联想"), new Memory("8G", "纽曼") });
54         Screen s3 = new Screen("1024*768", "16G");
55         Computer c3 = new Computer(3, "苹果", 4567.8, s3, ms3);
56 
57         return Arrays.asList(new Computer[] { c1, c2, c3 });
58     }
59 
60     private static Computer getComputer() {
61         List ms = Arrays.asList(new Memory[] { new Memory("16G", "金士顿"), new Memory("8G", "三星") });
62         return new Computer(7, "外星人", 12345.689, new Screen("1024*768", "16G"), ms);
63     }
64 
65 }

转载于:https://www.cnblogs.com/Oven5217/p/7553288.html