Jackson 来处理 JSON

Jackson 是一个 Java 用来处理 JSON 格式数据的类库

[代码] 首先创建一个User对象类 (User.java)

01	package com.sivalabs.json;

02

03	import java.util.Date;

04

05	public class User {

06	private String userId;

07	private UserName userName;

08	private Date dob;

09

10

@Override

11	public String toString(){

12	return "User [dob=" + dob + ", userId=" + userId + ", userName="+ userName + "]";

13

}

14	//setters and getters

15

16

}

[代码] UserName.java

01	package com.sivalabs.json;

02

03	public class UserName {

04	private String firstname;

05	private String middlename;

06	private String lastname;

07

08

@Override

09	public String toString()

10

{

11	return "UserName [firstname=" + firstname +

12	", lastname=" + lastname+

13	", middlename=" + middlename + "]";

14

}

15	//setters and getters

16

}

[代码] [Java]代码

01	//接下来创建User实例，并生成JSON数据

02

03	ObjectMapper mapper = new ObjectMapper();

04

05	UserName userName = new UserName();

06	userName.setFirstname("Katamreddy");

07	userName.setMiddlename("Siva");

08	userName.setLastname("PrasadReddy");

09

10	User user = new User();

11	user.setUserId("1");

12	user.setUserName(userName);

13	user.setDob(new Date());

14

15	Writer strWriter = new StringWriter();

16	mapper.writeValue(strWriter, user);

17	String userDataJSON = strWriter.toString();

18	System.out.println(userDataJSON);

[代码] 执行结果

01

{

02	"userId":"1",

03	"userName":

04

{

05	"firstname":"Katamreddy",

06	"middlename":"Siva",

07	"lastname":"PrasadReddy"

08

},

09	"dob":1300878089906

10

}

[代码] 接下来进行JSON到Java对象的转换

1	String userDataJSON =

2	"{\"userId\":\"100\",\"userName\":{\"firstname\":\"K\""+

3	",\"middlename\":\"Siva\",\"lastname\":\"Prasad\"},\"dob\":1300878089906}";

4	User userFromJSON = mapper.readValue(userDataJSON, User.class);

5	System.out.println(userFromJSON);

[代码] 时间的格式化处理

1	DateFormat dateFormat = new SimpleDateFormat("MM-dd-yyyy");

2	SerializationConfig serConfig = mapper.getSerializationConfig();

3	serConfig.setDateFormat(dateFormat);

4	DeserializationConfig deserializationConfig = mapper.getDeserializationConfig();

5	deserializationConfig.setDateFormat(dateFormat);

6	mapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESTAMPS, false);

[代码] [Java]代码

1	//从文件中读取JSON数据

2	User user = mapper.readValue(new File("user.json"), User.class);