JPA无法反序列化Java 8 LocalDateTime。

Question

我正在使用Spring Boot 1.5.1版本，在我的实体类中有一个LocalDateTime字段，每当我访问API时都会出现异常。

MySQL的dt列是TIMESTAMP类型。

JPA无法原生反序列化LocalDateTime吗？

执行GET请求时控制台输出如下：

 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>

- A_B

---

使用JPA转换器完成此任务。 - Mordechai

你可以尝试在私有的LocalDateTime dt上使用@Temporal(TemporalType.TIMESTAMP)和@Column，需要导入以下两个包： 1- import javax.persistence.Temporal; 2- import javax.persistence.TemporalType; - mibrahim.iti

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(); 
  }
}

确保将该转换器类添加到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JPA 2.0，这个答案可以帮助您使用@Temporal注释来处理LocalDateTime。

- grizzly

---

你不需要转换器。只需添加 hibernate-java8 依赖项。https://mvnrepository.com/artifact/org.hibernate/hibernate-java8 - Keysersoze

Answer 2

如果您使用支持 LocalDateTime 的较新版本的 hibernate-java8，则无需转换器。

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

- user1941489

---

示例展示了具有策划依赖项的POM。因此，这不是正确的方法。 - Witold Kaczurba

Answer 3

您可以在Spring包中找到一些已经准备好的转换器：

org.springframework.data.jpa.convert.threeten.Jsr310JpaConverters

JDocs：

JPA 2.1 转换器，将 JSR-310 类型转换为传统日期。要激活这些转换器，请确保您的持久性提供程序通过将此类包含在映射类列表中来检测它们。在 Spring 环境中，您可以简单地将此类的包（即 org.springframework.data.jpa.convert.threeten）注册为要扫描的包，例如 LocalContainerEntityManagerFactoryBean。

- Vlad D.

---

它支持自“Spring Data JPA 1.8”以来。 - Namo

Answer 4

你可以按照以下描述编写转换器：

@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();
   }
}

- Saurabh Nayar