Jackson库中objectMapper用法
ObjectMapper类是Jackson库的主要类。它提供一些功能将转换成Java对象与SON结构互相转换，在项目中遇到过，故记录一下。
在 pom.xml 加入依赖
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.8.3</version>
</dependency>
创建一个实体类RiemannUser：
package com.test.objectMapper;
import java.io.Serializable;
import java.util.Date;
import java.util.List;
/**
* @author riemann
* @date 2019/05/27 22:48
*/
public class RiemannUser implements Serializable {
private static final long serialVersionUID = 1L;
private int id;
private String message;
private Date sendDate;
private String nodeName;
private List<Integer> intList;
public RiemannUser() {
super();
}
public RiemannUser(int id, String message, Date sendDate) {
super();
this.id = id;
this.message = message;
this.sendDate = sendDate;
}
public static long getSerialVersionUID() {
return serialVersionUID;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public Date getSendDate() {
return sendDate;
}
public void setSendDate(Date sendDate) {
this.sendDate = sendDate;
}
public String getNodeName() {
return nodeName;
}
public void setNodeName(String nodeName) {
this.nodeName = nodeName;
}
public List<Integer> getIntList() {
return intList;
}
public void setIntList(List<Integer> intList) {
this.intList = intList;
}
@Override
public String toString() {
return "RiemannUser{" + "id=" + id + ", message='" + message + '\'' + ", sendDate=" + sendDate + ", nodeName='" + nodeName + '\'' + ", intList=" + intList + '}';
}
}
先创建一个ObjectMapper，然后赋值一些属性：
public static ObjectMapper mapper = new ObjectMapper();
static {
// 转换为格式化的json
mapper.enable(SerializationFeature.INDENT_OUTPUT);
// 如果json中有新增的字段并且是实体类类中不存在的，不报错
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
}
1、对象与json字符串、byte数组
@Test
public void testObject() throws JsonGenerationException, JsonMappingException, IOException {
RiemannUser riemann = new RiemannUser(1,"Hello World", new Date());
mapper.writeValue(new File("D:/test.txt"), riemann);//写到文件中
//mapper.writeValue(System.out, riemann); //写到控制台
String jsonStr = mapper.writeValueAsString(riemann);
System.out.println("对象转json字符串: " + jsonStr);
byte[] byteArr = mapper.writeValueAsBytes(riemann);
System.out.println("对象转为byte数组：" + byteArr);
RiemannUser riemannUser = mapper.readValue(jsonStr, RiemannUser.class);
System.out.println("json字符串转为对象：" + riemannUser);
RiemannUser riemannUser2 = mapper.readValue(byteArr, RiemannUser.class);
System.out.println("byte数组转为对象：" + riemannUser2);
}
运行结果：
对象转json字符串: {
“id” : 1,
“message” : “Hello World”,
“sendDate” : 1558971056693,
“nodeName” : null,
“intList” : null
}
对象转为byte数组：[B@31610302
json字符串转为对象：RiemannUser{id=1, message=’Hello World’, sendDate=Mon May 27 23本文来源gao*daima.com搞@代#码&网6:30:56 CST 2019, nodeName=’null’, intList=null}
byte数组转为对象：RiemannUser{id=1, message=’Hello World’, sendDate=Mon May 27 23:30:56 CST 2019, nodeName=’null’, intList=null}
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转载请注明原文链接：Jackson库中objectMapper的用法
转载请注明原文链接：Jackson库中objectMapper的用法
