Hibernate 5 入门指南-基于Envers

1. 首先创建\META-INF\persistence.xml配置文件并做简单的配置

   <persistence xmlns="http://java.sun.com/xml/ns/persistence"
                xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
                xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
                version="2.0">
   ​
       <persistence-unit name="org.hibernate.tutorial.envers">
           <description>
               Persistence unit for the JPA tutorial of the Hibernate Getting Started Guide
           </description>
   ​
           <properties>
               <property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver" />
               <property name="javax.persistence.jdbc.url" value="jdbc:mysql://localhost:3306/databaseName?useSSL=false&amp;serverTimezone=UTC&amp;verifyServerCertifate=false&amp;allowPublicKeyRetrieval=true" />
               <property name="javax.persistence.jdbc.user" value="root" />
               <property name="javax.persistence.jdbc.password" value="passwd" />
               <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL8Dialect"/>
               <property name="hibernate.show_sql" value="true" />
               <property name="hibernate.format_sql" value="true"/>
               <property name="hibernate.hbm2ddl.auto" value="create" />
           </properties>
   ​
       </persistence-unit>
   ​
   </persistence>

2. 创建实体Java类

   import java.util.Date;
   import javax.persistence.Column;
   import javax.persistence.Entity;
   import javax.persistence.GeneratedValue;
   import javax.persistence.Id;
   import javax.persistence.Table;
   import javax.persistence.Temporal;
   import javax.persistence.TemporalType;
   ​
   import org.hibernate.annotations.GenericGenerator;
   import org.hibernate.envers.Audited;
   ​
   @Entity
   @Table( name = "EVENTS" )
   @Audited  // <--- this tell Envers to audit (track changes to) this entity
   public class Event {
       private Long id;
   ​
       private String title;
       private Date date;
   ​
       public Event() {
           // this form used by Hibernate
       }
   ​
       public Event(String title, Date date) {
           // for application use, to create new events
           this.title = title;
           this.date = date;
       }
   ​
       @Id
       @GeneratedValue(generator="increment")
       @GenericGenerator(name="increment", strategy = "increment")
       public Long getId() {
           return id;
       }
   ​
       private void setId(Long id) {
           this.id = id;
       }
   ​
       @Temporal(TemporalType.TIMESTAMP)
       @Column(name = "EVENT_DATE")
       public Date getDate() {
           return date;
       }
   ​
       public void setDate(Date date) {
           this.date = date;    }​    public String getTitle() {        return title;    }​    public void setTitle(String title) {        this.title = title;    }​    @Override    public int hashCode() {        int result = title.hashCode();        result = 31 * result + date.hashCode();        return result;    }}

3. 向META-INF/persistence.xml文件中添加映射信息

   <class>类路径.Event</class>

4. JUnit测试测试程序

   import java.util.Date;
   import java.util.List;
   import javax.persistence.EntityManager;
   import javax.persistence.EntityManagerFactory;
   import javax.persistence.Persistence;
   ​
   import junit.framework.TestCase;
   ​
   import org.hibernate.envers.AuditReader;
   import org.hibernate.envers.AuditReaderFactory;
   ​
   /**
    * Illustrates the set up and use of Envers.
    * <p>
    * This example is different from the others in that we really need to save multiple revisions to the entity in
    * order to get a good look at Envers in action.
    *
    * @author Steve Ebersole
    */
   public class EnversIllustrationTest extends TestCase {
       private EntityManagerFactory entityManagerFactory;
   ​
       @Override
       protected void setUp() throws Exception {
           // like discussed with regards to SessionFactory, an EntityManagerFactory is set up once for an application
           //      IMPORTANT: notice how the name here matches the name we gave the persistence-unit in persistence.xml!
           entityManagerFactory = Persistence.createEntityManagerFactory( "org.hibernate.tutorial.envers" );
       }
   ​
       @Override
       protected void tearDown() throws Exception {
           entityManagerFactory.close();
       }
   ​
       public void testBasicUsage() {
           // create a couple of events
           EntityManager entityManager = entityManagerFactory.createEntityManager();
           entityManager.getTransaction().begin();
           entityManager.persist( new Event( "Our very first event!", new Date() ) );
           entityManager.persist( new Event( "A follow up event", new Date() ) );
           entityManager.getTransaction().commit();
           entityManager.close();
   ​
           // now lets pull events from the database and list them
           entityManager = entityManagerFactory.createEntityManager();
           entityManager.getTransaction().begin();
           List<Event> result = entityManager.createQuery( "from Event", Event.class ).getResultList();        for ( Event event : result ) {            System.out.println( "Event (" + event.getDate() + ") : " + event.getTitle() );        }        entityManager.getTransaction().commit();        entityManager.close();​        // so far the code is the same as we have seen in previous tutorials.  Now lets leverage Envers...​        // first lets create some revisions        entityManager = entityManagerFactory.createEntityManager();        entityManager.getTransaction().begin();        Event myEvent = entityManager.find( Event.class, 2L ); // we are using the increment generator, so we know 2 is a valid id        myEvent.setDate( new Date() );        myEvent.setTitle( myEvent.getTitle() + " (rescheduled)" );        entityManager.getTransaction().commit();        entityManager.close();​        // and then use an AuditReader to look back through history        entityManager = entityManagerFactory.createEntityManager();        entityManager.getTransaction().begin();        myEvent = entityManager.find( Event.class, 2L );        assertEquals( "A follow up event (rescheduled)", myEvent.getTitle() );        AuditReader reader = AuditReaderFactory.get( entityManager );        Event firstRevision = reader.find( Event.class, 2L, 1 );        assertFalse( firstRevision.getTitle().equals( myEvent.getTitle() ) );        assertFalse( firstRevision.getDate().equals( myEvent.getDate() ) );        Event secondRevision = reader.find( Event.class, 2L, 2 );        assertTrue( secondRevision.getTitle().equals( myEvent.getTitle() ) );        assertTrue( secondRevision.getDate().equals( myEvent.getDate() ) );        entityManager.getTransaction().commit();        entityManager.close();    }}

5. 运行测试