1.簡介

json是android與伺服器通訊過程中常用的資料格式，例如，如下是一個json格式的字串：

1. {"address":"Nanjing","name":"NUPT","students":[{"name":"stu1","id":"10000","age":20},{"name":"stu1","id":"10001","age":21},{"name":"stu1","id":"10002","age":22}]}  

定義Student類：

1. /* 
2.  * $filename: Student.java,v $ 
3.  * $Date: 2014-5-12  $ 
4.  * Copyright (C) ZhengHaibo, Inc. All rights reserved. 
5.  * This software is Made by Zhenghaibo. 
6.  */
7. package com.example.testjson;  
8. /* 
9.  *@author: ZhengHaibo   
10.  *web:     http://blog.csdn.net/nuptboyzhb 
11.  *mail:    [email protected] 
12.  *2014-5-12  Nanjing,njupt,China
     
13.  */
14. publicclass Student {  
15.     private String name;  
16.     private String id;  
17.     privateint age;  
18.     public String getName() {  
19.         return name;  
20.     }  
21.     publicvoid setName(String name) {  
22.         this.name = name;  
23.     }  
24.     public String getId() {  
25.         return id;  
26.     }  
27.     publicvoid setId(String id) {  
28.         this.id = id;  
29.     }  
30.     publicint getAge() {  
31.         return age;  
32.     }  
33.     publicvoid setAge(int age) {  
34.         this.age = age;  
35.     }  
36. }  

1. /* 
2.  * $filename: School.java,v $ 
3.  * $Date: 2014-5-12  $ 
4.  * Copyright (C) ZhengHaibo, Inc. All rights reserved. 
5.  * This software is Made by Zhenghaibo. 
6.  */
7. package com.example.testjson;  
8. import java.util.List;  
9. /* 
10.  *@author: ZhengHaibo   
11.  *web:     http://blog.csdn.net/nuptboyzhb 
12.  *mail:    [email protected] 
13.  *2014-5-12  Nanjing,njupt,China 
14.  */
15. publicclass School {  
16.     private String name;  
17.     private String address;  
18.     List<Student> students;  
19.     public String getName() {  
20.         return name;  
21.     }  
22.     publicvoid setName(String name) {  
23.         this.name = name;  
24.     }  
25.     public String getAddress() {  
26.         return address;  
27.     }  
28.     publicvoid setAddress(String address) {  
29.         this.address = address;  
30.     }  
31.     public List<Student> getStudents() {  
32.         return students;  
33.     }  
34.     publicvoid setStudents(List<Student> students) {  
35.         this.students = students;  
36.     }  
37. }  

1. private School initSchoolData(){  
2.             School school = new School();  
3.             school.setAddress("Nanjing");  
4.             school.setName("NUPT");  
5.             List<Student> list = new ArrayList<Student>();  
6.             for(int i= 0;i<3;i++){                 
7.                 Student student = new Student();  
8.                 student.setAge(20+i);  
9.                 student.setId("1000"+i);  
10.                 student.setName("stu"+1);  
11.                 list.add(student);  
12.             }  
13.             school.setStudents(list);  
14.             return school;  
15.         }  

3.使用Gson，進行java物件與json字串之間的相互轉換

1. privatevoid testGson(){  
2.             School school = initSchoolData();  
3.             Gson gson = new Gson();  
4.             //將物件轉化為json字串
5.             String jsonString = gson.toJson(school).toString();  
6.             //列印
7.             System.out.println("GSON="+jsonString);  
8.             /******分割線*****/
9.             //將字串轉化為JSON物件
10.             School resultSchool = gson.fromJson(jsonString, School.class);  
11.             //列印
12.             System.out.println(resultSchool.getStudents().get(0).getName());  
13.         }  

4.使用Jackson

1. privatevoid testJackson(){  
2.             School school = initSchoolData();  
3.             ObjectMapper objectMapper = new ObjectMapper();  
4.             String jsonString = "";  
5.             //將物件轉化為Json字串
6.             try {  
7.                 jsonString = objectMapper.writeValueAsString(school);  
8.                 System.out.println("Jackson="+jsonString);  
9.             } catch (JsonProcessingException e) {  
10.                 // TODO Auto-generated catch block
11.                 e.printStackTrace();  
12.             }  
13.             //將json字串解析成java物件
14.             try {  
15.                 School resultSchool = objectMapper.readValue(jsonString, School.class);  
16.                 //列印
17.                 System.out.println(resultSchool.getStudents().get(0).getName());  
18.             } catch (JsonParseException e) {  
19.                 // TODO Auto-generated catch block
20.                 e.printStackTrace();  
21.             } catch (JsonMappingException e) {  
22.                 // TODO Auto-generated catch block
23.                 e.printStackTrace();  
24.             } catch (IOException e) {  
25.                 // TODO Auto-generated catch block
26.                 e.printStackTrace();  
27.             }  
28.         }  

注意：以上只是這兩個工具類的基本用法，更多瞭解，參見官方文件。