JPA不能反序列化Java 8 LocalDateTime

Question

我使用SpringBoot1.5.1，当我的实体类中有一个LocalDateTime字段时，每当我访问API时都会得到异常。

MySQL dt列是时间戳。

JPA不能本机反序列化LocalDateTime吗？

执行GET请求时控制台输出

 2017-03-02 22:00:18.797 ERROR 13736 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is org.springframework.orm.jpa.JpaSystemException: could not deserialize; nested exception is org.hibernate.type.SerializationException: could not deserialize] with root cause

    java.io.StreamCorruptedException: invalid stream header: 20323031

Reservation.class

package com.example.springboot.reservation;

import java.time.LocalDateTime;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Table;

// Model class 

@Entity
@Table(name="reservation")
public class Reservation {

    @Id
    private Long id;

    @Column
    private LocalDateTime dt;


    @Column(name="user_id")
    private Long userId;

    // Hibernate will convert camel case column names to snake case!!!
    // Don't use camelcase columns in DB
    @Column(name="party_size")
    private int partySize;

    public Reservation() {}

    public Reservation(Long id,  Long userId, int partySize) {
        this.id = id;

        this.userId = userId;
        this.partySize = partySize;
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    public LocalDateTime getDt() {
        return dt;
    }

    public void setDt(LocalDateTime dt) {
        this.dt = dt;
    }

    public Long getUserId() {
        return userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    public int getPartySize() {
        return partySize;
    }

    public void setPartySize(int partySize) {
        this.partySize = partySize;
    }

}

pom.xml

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.1.RELEASE</version>
  </parent>

    <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>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

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

Answer 1

@Converter
public class LocalDateTimeConverter implements AttributeConverter<java.time.LocalDateTime, java.sql.Timestamp> {

  @Override
  public java.sql.Timestamp convertToDatabaseColumn(java.time.LocalDateTime entityValue) {
    return entityValue == null ? null : java.sql.Timestamp.valueOf(entityValue)
  }

  @Override
  public java.time.LocalDateTime convertToEntityAttribute(java.sql.Timestamp dbValue) {
    return dbValue == null ? null : dbValue.toLocalDateTime(); 
  }
}

确保将此转换器类添加到hibernate扫描的包中。将此转换器添加到列声明中

@Column
@Convert(converter = LocalDateTimeConverter.class)
private LocalDateTime dt;

如果您没有使用JPA2.0，这个answer将帮助您为LocalDateTime使用@Temporal注释。

Answer 2

如果使用具有LocalDateTime支持的较新的hibernate-java8 8，则不需要转换器。

<dependency>
  <groupId>org.hibernate</groupId>
  <artifactId>hibernate-java8</artifactId>
  <version>${hibernate.version}</version>
</dependency>

Answer 3

您可以编写如下所述的转换器：

@Converter(autoApply = true)
public class MyLocalDateConverter implements AttributeConverter<java.time.LocalDate, java.sql.Date> {

   @Override
   public java.sql.Date convertToDatabaseColumn(java.time.LocalDate attribute) {
      return attribute == null ? null : java.sql.Date.valueOf(attribute);
   }

   @Override
   public java.time.LocalDate convertToEntityAttribute(java.sql.Date dbData) {
    return dbData == null ? null : dbData.toLocalDate();
   }
}