@JsonFormat(pattern="yyyy-MM-dd") time difference problem

Recently, I was working on a course design project for a classmate,需要JavaThe backend returns the time to the frontend page、such as exam time、前端用的vue+element时间选择器、（use local time–北京时间）,Backend time field mapping,转换,But the data will be transmitted to the background in less time than Beijing time8个小时.The specific check is because of the time zone problem.But the front-end display is still small8个小时,If so, there is definitely a problem.可以利用@JsonFormatBinding to object properties solves the problem.

原因：@JsonFormat(pattern=“yyyy-MM-dd”）时间差问题

解释：默认情况下timeZone为GMT（即标准时区）,而北京是在东八区,所以会造成差8小时.

解决方法：加上timezone = "GMT+8

1 @JsonFormat(pattern=“yyyy-MM-dd HH:mm:ss”, timezone = “GMT+8”)

2 也可以在Springboot application.yml中修改MySQL配置

druid:    driver-class-name: com.mysql.cj.jdbc.Driver    url: jdbc:mysql://localhost:3306/renren_students?useUnicode=true&characterEncoding=UTF-8&serverTimezone=Asia/Shanghai    username: root    password: 123456

扩展知识：

注解@JsonFormat的使用

在项目maven引入@JsonFormat所需要的jar包.主要如下

<dependency>   <groupId>com.fasterxml.jackson.core</groupId>   <artifactId>jackson-annotations</artifactId>   <version>2.8.8</version></dependency><dependency>   <groupId>com.fasterxml.jackson.core</groupId>   <artifactId>jackson-databind</artifactId>   <version>2.8.8</version></dependency><dependency>   <groupId>org.codehaus.jackson</groupId>   <artifactId>jackson-mapper-asl</artifactId>   <version>1.9.13</version></dependency>

@JsonFormat注解是一个时间格式化注解,比如我们存储在mysql中的数据是date类型的,当我们读取出来封装在实体类中的时候,就会变成英文时间格式,而不是yyyy-MM-dd HH:mm:ss这样的中文时间,因此我们需要用到JsonFormat注解来格式化我们的时间.It is generally used for a field name to be added to the attribute of the entity class corresponding to the corresponding query database object [email protected]属性.//设置时区为上海时区,时间格式自己据需求定.比如：@JsonFormat(pattern=“yyyy-MM-dd”,timezone = “GMT+8”).

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