java - Hibernate映射异常: Unknown entity on session save

Question

当我从另一个类调用 addEventAction 方法时，使用 hibernate 对 postgresql 数据库进行保存操作时出现异常。

EventDAO.java:

package com.sessionpoint.session.sessiondr.core;

import java.util.ArrayList;
import java.util.List;
import java.util.logging.Logger;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;

import com.sessionpoint.session.sessiondr.db.DrAction;

/**
 * Logic for the database operations related to the actions.
 *
 */
public class EventDAO {

   //To get the logger for class
   Logger log = Logger.getLogger("EventDAO");

    /**
     * Add dispatched event action into the database.
     * 
     * @param eventAction
     */
    public void addEventAction(DrAction eventAction) {
        Transaction trns = null;
        Session session = HibernateUtil.getSessionFactory().openSession();

        log.info("Connection with the database created successfuly.");

        try {
            trns = session.beginTransaction();
            session.save(eventAction); //exception here
            session.getTransaction().commit();
        } catch (RuntimeException e) {
            if (trns != null) {
                trns.rollback();
            }
            e.printStackTrace();
        } finally {
            session.flush();
            session.close();
        }
    }
}

HibernateUtil.java:

public class HibernateUtil {
    private static SessionFactory sessionFactory;

    //To get the logger for class
    static Logger log = Logger.getLogger("HibernateUtil");

    static {

        log.info("Trying to create a connection with the database.");
        Configuration configuration = new Configuration();
        configuration.configure("hibernate.cfg.xml");
        StandardServiceRegistryBuilder ssrb = new StandardServiceRegistryBuilder()
                .applySettings(configuration.getProperties());
        sessionFactory = configuration.buildSessionFactory(ssrb.build());
    }

    public static SessionFactory getSessionFactory() {
        return sessionFactory;
    }
}

异常跟踪:

org.hibernate.MappingException: Unknown entity: com.sessionpoint.session.sessiondr.db.DrAction
    at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:1094)
    at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1439)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:116)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:209)
    at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:194)
    at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
    at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:711)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:703)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:698)
    at com.sessionpoint.session.sessiondr.core.EventDAO.addEventAction(EventDAO.java:35)

更新:

hibernate.cfg.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
        <property name="hibernate.connection.password">user</property>
        <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/drcore</property>
        <property name="hibernate.connection.username">postgres</property>
        <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
    </session-factory>
</hibernate-configuration>

DrAction.java:

/**
 * DrAction for the dr_action table
 */
public class DrAction implements java.io.Serializable {

    /**
     * Default serial version Id.
     */
    private static final long serialVersionUID = 1L;

    /**
     * Auto increment drActionId.
     */
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private long drActionId;
    private String drVName;
    private String drVRequestId;

    private Long vKey;

    public long getDrActionId() {
        return drActionId;
    }
    public void setDrActionId(long drActionId) {
        this.drActionId = drActionId;
    }
    public Long getvKey() {
        return vKey;
    }
    public void setvKey(Long vKey) {
        this.vKey = vKey;
    }
    public String getDrVName() {
        return drVName;
    }
    public void setDrVName(String drVName) {
        this.drVName = drVName;
    }
    public String getDrVRequestId() {
        return drVRequestId;
    }
    public void setDrVRequestId(String drVRequestId) {
        this.drVRequestId = drVRequestId;
    }
}

更新:

异常跟踪2:

org.hibernate.exception.SQLGrammarException: could not extract ResultSet
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:123)
    at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:126)
    at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:112)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:89)
    at org.hibernate.id.SequenceGenerator.generateHolder(SequenceGenerator.java:122)
    at org.hibernate.id.SequenceGenerator.generate(SequenceGenerator.java:115)
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:117)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:209)
    at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:55)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:194)
    at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:49)
    at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:90)
    at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:711)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:703)
    at org.hibernate.internal.SessionImpl.save(SessionImpl.java:698)
    at com.sessionpoint.session.sessiondr.core.EventDAO.addEventAction(EventDAO.java:35)    
    at java.lang.Thread.run(Thread.java:745)
Caused by: org.postgresql.util.PSQLException: ERROR: relation "hibernate_sequence" does not exist
  Position: 17
    at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2157)
    at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1886)
    at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:255)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:555)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:417)
    at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:302)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.extract(ResultSetReturnImpl.java:80)

更新:

异常跟踪3:

Caused by: org.hibernate.MappingNotFoundException: resource: com/sessionpoint/session/sessiondr/db/DrAction.hbm.xml not found
    at org.hibernate.cfg.Configuration.addResource(Configuration.java:767)
    at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:2255)
    at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:2227)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2207)
    at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:2160)
    at org.hibernate.cfg.Configuration.configure(Configuration.java:2075)
    at com.sessionpoint.session.sessiondr.core.HibernateUtil.<clinit>(HibernateUtil.java:24)

Answer 1

添加@Entity至DrAction类，并添加 <mapping class="your.package.DrAction"/>至hibernate.cfg.xml .

@Entity
@Table(name = "dr_action")
public class DrAction implements java.io.Serializable {

hibernate.cfg.xml

...
    <session-factory>
        ....
        <mapping class="your.package.DrAction"/>
    </session-factory>
....

更新

您可能正在使用 Oracle 作为数据库，而 Oracle 不支持自动生成的 id。您必须指定用于生成 id 的序列。

在数据库中执行此操作

create sequence DR_ACTION_SEQ;

并将 id 映射更改为此

@Id 
@GeneratedValue(generator="drActionIdSeq") 
@SequenceGenerator(name="drActionIdSeq",sequenceName="DR_ACTION_SEQ", allocationSize=5)
private long drActionId;

请注意，这要求您的 id 列名为 dractionid ，如果不是，那么您必须添加 @Column字段注释，类似这样

@Column(name = "dr_action_id")

您必须对名称与数据库表中的列不同的每个列执行此操作。