java - 为什么每次调用findById()时Calendar字段都会自动增加

Question

当我使用spring-boot 2.1.7.release和mysql 5.6编码时，出现一些错误。过程如下:

首先，我将一个实体保存到数据库中。该实体有一个名为 applyTime 的字段，类型为 Calendar然后，调用findById()。最后，applyTime 会自动增加一些数字。

示例:保存值的timeInMillis为2000000L，findById()返回值的timeInMillis为70400000。

当更新实体的其他字段时，日历字段将保留新值。

我创建了一个带有示例两个类的圆顶，即Student和StudentRepository。并且错误也出现了。

实体

@Entity
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String name;

    private Calendar applyTime;

    // setter and getter ...
}

DAO

public interface StudentRepository extends CrudRepository<Student, Long> {
}

测试

    @Test
    public void test() {
        Student student = new Student();
        Calendar calendar = Calendar.getInstance();
        long time = 20000000L;
        /** init with 20,000,000 */
        calendar.setTimeInMillis(time);
        student.setApplyTime(calendar);

        /** save entity with: 20,000,000 (1970/1/1 13:33:20 +8:00). database: 1970-01-01 13:33:20 +8:00 */
        studentRepository.save(student);

        Student student1 = studentRepository.findById(student.getId()).get();
        Assertions.assertThat(student1.getApplyTime().getTimeInMillis()).isGreaterThan(time);

        /** get 70400000 (1970/1/2 3:33:20 +8:00) , database:  1970-01-01 13:33:20 (+8:00)*/
        time = student1.getApplyTime().getTimeInMillis();
        logger.warn(String.valueOf(time));

        student1.setName("hi");
        studentRepository.save(student1);

        student1 = studentRepository.findById(student.getId()).get();
        Assertions.assertThat(student1.getApplyTime().getTimeInMillis()).isGreaterThan(time);
        time = student1.getApplyTime().getTimeInMillis();

        /** get  120800000(1970/1/2 17:33:20 +8:00), database: 1970-01-02 03:33:20  you may get other auto increase value*/
        logger.warn(String.valueOf(time));

        student1.setName("hello");
        studentRepository.save(student1);

        student1 = studentRepository.findById(student.getId()).get();
        Assertions.assertThat(student1.getApplyTime().getTimeInMillis()).isGreaterThan(time);
        time = student1.getApplyTime().getTimeInMillis();

        /** get 171200000(1970/1/3 7:33:20 +8:00) database: 1970-01-02 17:33:20 +8:00*/
        logger.warn(String.valueOf(time));
    }

mysql

version: '3.1'

services:

  db:
    image: mysql:5.6
    command: --default-authentication-plugin=mysql_native_password
    restart: always
    environment:
      MYSQL_ROOT_PASSWORD: example
      MYSQL_DATABASE: example
    volumes:
      - ./mysql:/var/lib/mysql
    ports:
      - 3316:3306

pom

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

应用程序.yml

# 测试环境
spring:
  jpa:
    hibernate:
      ddl-auto: create-drop
    properties:
      hibernate:
        dialect: org.hibernate.dialect.MySQL5InnoDBDialect
    show-sql: true
  datasource:
    url: jdbc:mysql://127.0.0.1:3316/example?useUnicode=true&characterEncoding=utf-8&useSSL=false
    username: root
    password: example
    separator: //

logging:
  level:
    org:
      hibernate:
        type:
          descriptor:
            sql:
              BasicBinder: TRACE
debug: false

github:https://github.com/mengyunzhi/jpa-calendar-error

如何禁用自动增加日历字段？谢谢!

Answer 1

当您将其中一个字段定义为日历类型时，您需要对其进行相应的注释，以防止出现任何不一致:

@Temporal(TemporalType.DATE)
private Calendar applyTime;

@Temporal(TemporalType.TIMESTAMP)
private Calendar applyTime;