hibernate多对一双向关联

【例】图书与出版社

第一步：创建数据库表

图书表

出版社表

第二步：创建实体类

product.java

package com.dwx.entity;
public class Product {
	private int id;
	private String name;
	private double price;
	private Factory factory;
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public double getPrice() {
		return price;
	}
	public void setPrice(double price) {
		this.price = price;
	}
	public Factory getFactory() {
		return factory;
	}
	public void setFactory(Factory factory) {
		this.factory = factory;
	}
}

factory.java

package com.dwx.entity;
import java.util.Set;
public class Factory {
	private int factory_id;
	private String name;
	private Set<Product>products;
	public Set<Product> getProducts() {
		return products;
	}
	public void setProducts(Set<Product> products) {
		this.products = products;
	}
	public int getFactory_id() {
		return factory_id;
	}
	public void setFactory_id(int factory_id) {
		this.factory_id = factory_id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
}

第三步：配置映射文件

Product.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.dwx.entity.Product" table="product" catalog="register">
		<id name="id" column="id">
			<generator class="native"></generator>
		</id>
		<property name="name" column="name"></property>
		<property name="price" column="price"></property>
		<many-to-one name="factory" class="com.dwx.entity.Factory" cascade="save-update">
			<column name="factory_id"></column>
		</many-to-one>
	</class>
</hibernate-mapping>

Factory.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
	<class name="com.dwx.entity.Factory" table="factory">
		<id name="factory_id" column="factory_id">
			<generator class="native"></generator>
		</id>
		<property name="name" column="name"></property>
		<set name="products" cascade="save-update" inverse="true">
			<key column="factory_id"></key>
			<one-to-many class="com.dwx.entity.Product"/>
		</set>
	</class>
</hibernate-mapping>

第四步：创建HibernateSessionFactory

package com.dwx.utils;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

/**
 * Configures and provides access to Hibernate sessions, tied to the
 * current thread of execution.  Follows the Thread Local Session
 * pattern, see {@link http://hibernate.org/42.html }.
 */
public class HibernateSessionFactory {

    /** 
     * Location of hibernate.cfg.xml file.
     * Location should be on the classpath as Hibernate uses  
     * #resourceAsStream style lookup for its configuration file. 
     * The default classpath location of the hibernate config file is 
     * in the default package. Use #setConfigFile() to update 
     * the location of the configuration file for the current session.   
     */
	private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
    private static org.hibernate.SessionFactory sessionFactory;
	
    private static Configuration configuration = new Configuration();
    private static ServiceRegistry serviceRegistry; 

	static {
    	try {
			configuration.configure();
			serviceRegistry = new StandardServiceRegistryBuilder().configure().build();
			try {
				sessionFactory = new MetadataSources(serviceRegistry).buildMetadata().buildSessionFactory();
			} catch (Exception e) {
				StandardServiceRegistryBuilder.destroy(serviceRegistry);
				e.printStackTrace();
			}
		} catch (Exception e) {
			System.err.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
    }
    private HibernateSessionFactory() {
    }
	
	/**
     * Returns the ThreadLocal Session instance.  Lazy initialize
     * the <code>SessionFactory</code> if needed.
     *
     *  @return Session
     *  @throws HibernateException
     */
    public static Session getSession() throws HibernateException {
        Session session = (Session) threadLocal.get();

		if (session == null || !session.isOpen()) {
			if (sessionFactory == null) {
				rebuildSessionFactory();
			}
			session = (sessionFactory != null) ? sessionFactory.openSession()
					: null;
			threadLocal.set(session);
		}

        return session;
    }

	/**
     *  Rebuild hibernate session factory
     *
     */
	public static void rebuildSessionFactory() {
		try {
			configuration.configure();
			serviceRegistry = new StandardServiceRegistryBuilder().configure().build();
			try {
				sessionFactory = new MetadataSources(serviceRegistry).buildMetadata().buildSessionFactory();
			} catch (Exception e) {
				StandardServiceRegistryBuilder.destroy(serviceRegistry);
				e.printStackTrace();
			}
		} catch (Exception e) {
			System.err.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
	}

	/**
     *  Close the single hibernate session instance.
     *
     *  @throws HibernateException
     */
    public static void closeSession() throws HibernateException {
        Session session = (Session) threadLocal.get();
        threadLocal.set(null);

        if (session != null) {
            session.close();
        }
    }

	/**
     *  return session factory
     *
     */
	public static org.hibernate.SessionFactory getSessionFactory() {
		return sessionFactory;
	}
	/**
     *  return hibernate configuration
     *
     */
	public static Configuration getConfiguration() {
		return configuration;
	}

}

第五步：创建测试类

package com.dwx.bz;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.dwx.entity.Factory;
import com.dwx.entity.Product;
import com.dwx.entity.Student;
import com.dwx.utils.HibernateSessionFactory;
public class ProductBz {
	public void addProduct(){
		Session session=null;
		Transaction tx=null;
		try{
			Product product=new Product();
			product.setName("HTML5从入门到精通");
			product.setPrice(56.00);			
			
			Product product1=new Product();
			product1.setName("DIV+CSS网页布局");
			product1.setPrice(45.00);	
			
			Set<Product>set=new HashSet<Product>();
			set.add(product);
			set.add(product1);
			
			Factory factory=new Factory();
			factory.setName("电子工业出版社");
			factory.setProducts(set);
			product.setFactory(factory);
			product1.setFactory(factory);
						
			session=HibernateSessionFactory.getSession();
			tx=session.beginTransaction();	
			session.save(factory);
			tx.commit();
		}catch(Exception e){
			e.printStackTrace();
		}finally{
			HibernateSessionFactory.closeSession();
		}
	}
	public static void main(String[] args) {
		ProductBz pb=new ProductBz();
		pb.addProduct();
		Session session=HibernateSessionFactory.getSession();
		List<Factory>list=session.createQuery("from Factory").list();
		for(Iterator it=list.iterator();it.hasNext();){
  			Factory factory=(Factory)it.next();
  			System.out.println(factory.getName());
  			for(Iterator product=factory.getProducts().iterator();product.hasNext();){
  				Product pro=(Product)product.next();
  				System.out.println(pro.getName()+","+pro.getPrice());
  			}			
  		}
  		HibernateSessionFactory.closeSession();
	}
}

效果：

查看数据库表