/*
* Created on 2006-2-5
* @author icerain
*/
package test.test;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.EntityResult;
import javax.persistence.FieldResult;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.SqlResultSetMapping;

@Entity(name = "Item")
//    @SqlResultSetMapping(name = "getItem", entities =
//    @EntityResult(name = "org.hibernate.ejb.test.Item", fields = {
//    @FieldResult(name = "name", column = "itemname"),
//    @FieldResult(name = "descr", column = "itemdescription")
//    })
//)
//@Cache(region="Item", usage=NONSTRICT_READ_WRITE)
public class Item implements Serializable {

  private String name;
  private String descr;
  //private Set distributors;

  public Item() {
  }

  public Item(String name, String desc) {
    this.name = name;
    this.descr = desc;
  }

  @Column(length = 200)
  public String getDescr() {
    return descr;
  }

  public void setDescr(String desc) {
    this.descr = desc;
  }

  @Id
  @Column(length = 30)
  public String getName() {
    return name;
  }

  public void setName(String name) {
    this.name = name;
  }

//  @OneToMany
//  public Set getDistributors() {
//    return distributors;
//  }
//
//  public void setDistributors(Set distributors) {
//    this.distributors = distributors;
//  }
//
//  public void addDistributor(Distributor d) {
//    if ( distributors == null ) distributors = new HashSet();
//    distributors.add( d );
//  }
}

下面是测试和配置的代码:

/*
* Created on 2006-2-5
* @author icerain
*/
package test.test;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Map;
import java.util.Properties;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

import org.hibernate.cfg.Environment;
import org.hibernate.ejb.Ejb3Configuration;
import org.hibernate.ejb.HibernatePersistence;

public class TestConfig {
  private EntityManagerFactory emf = null;

  public TestConfig() {
    this(null);
  }
  public TestConfig(String fileName) {
    // 利用Ejb3Configuration来建立EntityManagerFactory
    emf = new Ejb3Configuration().addAnnotatedClass(Item.class).createEntityManagerFactory();  //(1) 看下面解释
    //emf = Persistence.createEntityManagerFactory("manager1"); // 在JSE环境中不可以使用??? (2) 看下面解释
    System.out.println("Create EMF:::::");
  // 利用HibernatePersistence来建立EntityManagerFactory
    //emf = new HibernatePersistence().createEntityManagerFactory(getConfig());  //(3) 看下面解释
  }
 
  public  Properties loadProperties() {
    Properties props = new Properties();
    InputStream stream = Persistence.class.getResourceAsStream( "/hibernate.properties" );
    if ( stream != null ) {
      try {
        props.load( stream );
      }
      catch (Exception e) {
        throw new RuntimeException( "could not load hibernate.properties" );
      }
      finally {
        try {
          stream.close();
        }
        catch (IOException ioe) {
        }
      }
    }
    props.setProperty( Environment.HBM2DDL_AUTO, "create-drop" );
    return props;
  }

  private Map getConfig() {
    Map config = loadProperties();
    ArrayList classes = new ArrayList();

    classes.add(Item.class);
    config.put( HibernatePersistence.LOADED_CLASSES, classes );
   
    return config;
  }
 
  public void testEntityManager() { // 测试持久化数据操作 (4)

    Item item = new Item( "Mouse1", "Micro$oft mouse" );

    EntityManager em = emf.createEntityManager();
    em.getTransaction().begin();
    em.persist( item );
    System.out.println( em.contains( item ) );
    em.getTransaction().commit();

    System.out.println(em.contains(item));

    em.getTransaction().begin();
    item = (Item) em.createQuery( "from Item where descr like M%" ).getSingleResult();
   
    System.out.println(item.getDescr() + ":" + item.getName());
   
    item.setDescr( "Micro$oft wireless mouse" );
    em.getTransaction().commit();
   
    System.out.println(item.getDescr() + ":" + item.getName());

    em.close();
    closeEMF();

  }
 
  public void closeEMF() {
    emf.close();
    System.out.println("EMF is closed..");
  }

  /**
   * @param args
   */
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    new TestConfig().testEntityManager();
  }

}

　　上面就是测试代码,可以看到,我们可以用不同的方法来创建 EntityManagerFactory , 之所以有这么多方法是为了在不同的环境中使用的.

(1): 利用Ejb3Configuration来建立EntityManagerFactory ,她会在工程目录下寻找hibernate.properties 配置文件(hibernate.cfg.xml好像不可以,大家可以试试看),然后根据配置信息来创建EntityManagerFactory .
配置文件如下:

#Created by JInto - www.guh-software.de
#Sun Feb 05 22:38:30 CST 2006
hibernate.cache.provider_class=org.hibernate.cache.HashtableCacheProvider
hibernate.cache.region_prefix=hibernate.test
hibernate.connection.driver_class=com.mysql.jdbc.Driver
hibernate.connection.password=329
hibernate.connection.pool_size=1
hibernate.connection.url=jdbc\:mysql\://localhost/test3
hibernate.connection.username=root
hibernate.default_batch_fetch_size=8
hibernate.dialect=org.hibernate.dialect.MySQLDialect
hibernate.hbm2ddl.auto=update
hibernate.jdbc.batch_versioned_data=true
hibernate.jdbc.use_streams_for_binary=true
hibernate.max_fetch_depth=1
hibernate.order_updates=true
hibernate.proxool.pool_alias=pool1
hibernate.query.substitutions=true 1, false 0, yes Y, no N
javax.persistence.provider=org.hibernate.ejb.HibernatePersistence

(2)文档上说利用Persistence可以创建的 但是我利用不同方法试了几下,都不可以,大家可以试试 如果你知道如何用 要记得告诉我哦 :).

(3) 利用HibernatePersistence来建立EntityManagerFactory, 她可以利用一个properties 来创建, 该properties 你可以随便创建 只有包含必要的配置信息就可以了, 上面的代码中用了一个Map .

(4):  调用testEntityManager() 方法 测试持久化数据操作 .

ok, 到此一个简单的在JSE环境中使用EntityManger的介绍就结束了.