用 Jackson 来处理 JSON，jackson来处理json,Jackson 是一个

用 Jackson 来处理 JSON，jackson来处理json,Jackson 是一个

Jackson 是一个 Java 用来处理 JSON 格式数据的类库，性能非常好。

首先创建一个User对象类 (User.java)

package com.sivalabs.json;import java.util.Date;public class User { private String userId; private UserName userName; private Date dob; @Override public String toString(){  return "User [dob=" + dob + ", userId=" + userId + ", userName="+ userName + "]"; } //setters and getters}

UserName.java

package com.sivalabs.json;public class UserName { private String firstname; private String middlename; private String lastname; @Override public String toString() {  return "UserName [firstname=" + firstname +   ", lastname=" + lastname+   ", middlename=" + middlename + "]"; } //setters and getters}

[Java]代码

//接下来创建User实例，并生成JSON数据ObjectMapper mapper = new ObjectMapper();UserName userName = new UserName();userName.setFirstname("Katamreddy");userName.setMiddlename("Siva");userName.setLastname("PrasadReddy");User user = new User();user.setUserId("1");user.setUserName(userName);user.setDob(new Date());Writer strWriter = new StringWriter();mapper.writeValue(strWriter, user);String userDataJSON = strWriter.toString();System.out.println(userDataJSON);

执行结果

{"userId":"1","userName":{"firstname":"Katamreddy","middlename":"Siva","lastname":"PrasadReddy"},"dob":1300878089906}

接下来进行JSON到Java对象的转换

String userDataJSON = "{\"userId\":\"100\",\"userName\":{\"firstname\":\"K\""+",\"middlename\":\"Siva\",\"lastname\":\"Prasad\"},\"dob\":1300878089906}";User userFromJSON = mapper.readValue(userDataJSON, User.class);System.out.println(userFromJSON);

时间的格式化处理

DateFormat dateFormat = new SimpleDateFormat("MM-dd-yyyy");SerializationConfig serConfig = mapper.getSerializationConfig();serConfig.setDateFormat(dateFormat);DeserializationConfig deserializationConfig = mapper.getDeserializationConfig();deserializationConfig.setDateFormat(dateFormat);mapper.configure(SerializationConfig.Feature.WRITE_DATES_AS_TIMESTAMPS, false);

[Java]代码

//从文件中读取JSON数据User user = mapper.readValue(new File("user.json"), User.class);