Hibernate 5 入门指南-基于映射文件

由于Hibernate 4版本混乱，Hibernate 3有些过时，Hibernate 5的开发文档尚不完善，所以构建一份简单的Hibernate 5的入门指南

注：案例参考Hibernate 官方参考文档，使用Hibernate 5.3.7 、Java 8 -191、MySQL 8.0. 13进行修改测试

本案例使用hbm.xml映射文件创建简单的Hibernate测试项目

1. 首先创建hibernate.cfg.xml配置文件并做简单的配置。

   <hibernate-configuration>
       <session-factory>
           <!-- Database connection settings -->
           <property name="connection.url">jdbc:mysql://localhost:3306/databaseName?useSSL=false&amp;serverTimezone=UTC&amp;verifyServerCertifate=false&amp;allowPublicKeyRetrieval=true</property>
           <property name="connection.driver_class">com.mysql.cj.jdbc.Driver</property>
           <property name="connection.username">root</property>
           <property name="connection.password">passwd</property>
   ​
           <!-- SQL dialect -->
           <property name="dialect">org.hibernate.dialect.MySQL8Dialect</property>
   ​
           <!-- Echo all executed SQL to stdout -->
           <property name="show_sql">true</property>
           <property name="format_sql">true</property>
   ​
           <!-- Drop and re-create the database schema on startup -->
           <!--先定义为create使其在数据库生成对应的表，之后可以修改为update-->
           <property name="hbm2ddl.auto">create</property>
   ​
           <!-- JDBC connection pool (use the built-in) -->
           <property name="connection.pool_size">1</property>
   ​
           <!-- Disable the second-level cache  -->
           <property name="cache.provider_class">org.hibernate.cache.internal.NoCachingRegionFactory</property>
       </session-factory>
   </hibernate-configuration>

2. 创建实体Java类

   import java.util.Date;
   ​
   public class Event {
       private Long id;
       private String title;
       private Date date;
   ​
       public Event() {
       }
   ​
       public Event(String title, Date date) {
           this.title = title;
           this.date = date;
       }
   ​
       public Long getId() {
           return id;
       }
   ​
       public void setId(Long id) {
           this.id = id;
       }
   ​
       public String getTitle() {
           return title;
       }
   ​
       public void setTitle(String title) {
           this.title = title;
       }
   ​
       public Date getDate() {
           return date;
       }
   ​
       public void setDate(Date date) {
           this.date = date;
       }
   }

3. 创建Event.hbm.xml映射文件

   <hibernate-mapping package="类路径">
       <class name="Event" table="EVENTS">
           <!--定义id映射元素主键自增-->
           <id name="id" column="EVENTS_ID">
               <generator class="increment"/>
           </id>
           <!--定义属性映射元素-->
           <property name="date" column="EVENT_DATE" type="timestamp"/>
           <property name="title"/>
       </class>
   </hibernate-mapping>

4. 向hibernate.cfg.xml文件中添加映射信息

   <mapping resource="类路径/Event.hbm.xml"/>

5. JUnit测试测试程序

   import java.util.Date;
   import java.util.List;
   ​
   import org.hibernate.Session;
   import org.hibernate.SessionFactory;
   import org.hibernate.boot.MetadataSources;
   import org.hibernate.boot.registry.StandardServiceRegistry;
   import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
   ​
   import junit.framework.TestCase;
   ​
   public class NativeApiIllustrationTest extends TestCase {
       private SessionFactory sessionFactory;
       protected void setUp() throws Exception {
           // A SessionFactory is set up once for an application!
           final StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
                   .configure() // configures settings from hibernate.cfg.xml
                   .build();
           try {
               sessionFactory = new MetadataSources( registry ).buildMetadata().buildSessionFactory();
           }
           catch (Exception e) {
               // The registry would be destroyed by the SessionFactory, but we had trouble building the SessionFactory
               // so destroy it manually.
               StandardServiceRegistryBuilder.destroy( registry );
           }
       }
   ​
       @Override
       protected void tearDown() throws Exception {
           if ( sessionFactory != null ) {
               sessionFactory.close();
           }
       }
   ​
       @SuppressWarnings("unchecked")
       public void testBasicUsage() {
           // create a couple of events...
           Session session = sessionFactory.openSession();
           session.beginTransaction();
           session.save( new Event( "Our very first event!", new Date() ) );
           session.save( new Event( "A follow up event", new Date() ) );
           session.getTransaction().commit();
           session.close();
   ​
           // now lets pull events from the database and list them
           session = sessionFactory.openSession();
           session.beginTransaction();
           List result = session.createQuery( "from Event" ).list();
           for ( Event event : (List<Event>) result ) {
               System.out.println( "Event (" + event.getDate() + ") : " + event.getTitle() );        }        session.getTransaction().commit();        session.close();    }}

6. 运行测试