Java JPA，什么时候实体必须实现可序列化

我目前正在学习JPA。在文档中，它指出只有当实体被其他JVM远程分离时，它才需要是可序列化的

然而，出于测试目的，我将实体创建为持久性类（CDI）的内部私有类。 当我尝试使用EntityManager持久化实体时。我得到一个例外，如下所示：

Caused by: Exception [EclipseLink-7155] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ValidationException
Exception Description: The type [class minh.ea.common.Ultilities.DatabaseLogger] for the attribute [this$0] on the entity class [class minh.ea.common.Ultilities.DatabaseLogger$LogRecord] is not a valid type for a serialized mapping. The attribute type must implement the Serializable interface.

package minh.ea.common.Ultilities;

import java.util.Date;
import javax.enterprise.context.ApplicationScoped;
import javax.persistence.Entity;
import javax.persistence.EntityManager;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.PersistenceContext;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.transaction.Transactional;

/**
 *
 * @author Minh
 */

@ApplicationScoped
@minh.ea.common.Ultilities.qualifiers.Database
public class DatabaseLogger implements Logger {

    @PersistenceContext
    private EntityManager em;

    private final long MAX_SIZE=2097152;

    public DatabaseLogger(){

    }

    @Override
    @Transactional
    public void info(Object obj) {
        em.persist(new RecordEntry("INFO", new Date(), obj.toString()));
    }

    @Override
    @Transactional
    public void warn(Object obj) {
        em.persist(new RecordEntry("WARN", new Date(), obj.toString()));
    }

    @Override
    @Transactional
    public void error(Object obj) {
        em.persist(new RecordEntry("ERROR", new Date(), obj.toString()));
    }

    @Override
    @Transactional
    public void fatal(Object obj) {
        em.persist(new RecordEntry("FATAL", new Date(), obj.toString()));
    }

    @Entity
    public class LogRecord{

        @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
        private int id;
        private String type;
        @Temporal(TemporalType.TIMESTAMP)
        private Date time;
        private String message;

        public String getType() {
            return type;
        }

        public void setType(String type) {
            this.type = type;
        }

        public Date getTime() {
            return time;
        }

        public void setTime(Date time) {
            this.time = time;
        }

        public String getMessage() {
            return message;
        }

        public void setMessage(String message) {
            this.message = message;
        }

        public LogRecord() {
        }

        public LogRecord(String type, Date time, String message) {
            this.type = type;
            this.time = time;
            this.message = message;
        }
    }

}

正如我所理解的，这个异常意味着我的实体属性和类一样需要是可序列化的。那么，原因是什么，它被传递到了哪里

所有这些都在GlassFish 4.0容器下运行。使用EclipseLink 2.1的JPA

我对持久性和内部实体的实现如下：

Caused by: Exception [EclipseLink-7155] (Eclipse Persistence Services - 2.5.0.v20130507-3faac2b): org.eclipse.persistence.exceptions.ValidationException
Exception Description: The type [class minh.ea.common.Ultilities.DatabaseLogger] for the attribute [this$0] on the entity class [class minh.ea.common.Ultilities.DatabaseLogger$LogRecord] is not a valid type for a serialized mapping. The attribute type must implement the Serializable interface.

package minh.ea.common.Ultilities;

import java.util.Date;
import javax.enterprise.context.ApplicationScoped;
import javax.persistence.Entity;
import javax.persistence.EntityManager;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.PersistenceContext;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.transaction.Transactional;

/**
 *
 * @author Minh
 */

@ApplicationScoped
@minh.ea.common.Ultilities.qualifiers.Database
public class DatabaseLogger implements Logger {

    @PersistenceContext
    private EntityManager em;

    private final long MAX_SIZE=2097152;

    public DatabaseLogger(){

    }

    @Override
    @Transactional
    public void info(Object obj) {
        em.persist(new RecordEntry("INFO", new Date(), obj.toString()));
    }

    @Override
    @Transactional
    public void warn(Object obj) {
        em.persist(new RecordEntry("WARN", new Date(), obj.toString()));
    }

    @Override
    @Transactional
    public void error(Object obj) {
        em.persist(new RecordEntry("ERROR", new Date(), obj.toString()));
    }

    @Override
    @Transactional
    public void fatal(Object obj) {
        em.persist(new RecordEntry("FATAL", new Date(), obj.toString()));
    }

    @Entity
    public class LogRecord{

        @Id @GeneratedValue(strategy = GenerationType.IDENTITY)
        private int id;
        private String type;
        @Temporal(TemporalType.TIMESTAMP)
        private Date time;
        private String message;

        public String getType() {
            return type;
        }

        public void setType(String type) {
            this.type = type;
        }

        public Date getTime() {
            return time;
        }

        public void setTime(Date time) {
            this.time = time;
        }

        public String getMessage() {
            return message;
        }

        public void setMessage(String message) {
            this.message = message;
        }

        public LogRecord() {
        }

        public LogRecord(String type, Date time, String message) {
            this.type = type;
            this.time = time;
            this.message = message;
        }
    }

}

请注意，

根据，有效的

实体

类必须是顶级类，这意味着您的内部类将无法工作

---

试着把它拉到自己的

实体

类中，因为它会在一个合适的系统中，然后再次保存。

谢谢，这是真的，但是你能帮我理解为什么它会输出一个关于序列化的错误吗？你的

RecordEntry

类的映射是什么样子的？它提到了序列化，因为你的实体是一个内部类，所以自动有一个$0的属性指向JPA被迫映射的外部类。由于该属性不是实体或基本类型，因此它默认使用可序列化映射，因此出现异常。如果它是可序列化的，它将尝试将外部实例序列化为表中的lob字段。感谢Chris的精彩解释。