hibernate多对一单向关联

灰太狼 2022-05-24 08:39 295阅读 0赞

#### 【例】图书与出版社   第一步：创建数据库表 ####

##### 图书表 #####

![20180524095754206][]

##### 出版社表 #####

![20180524095822400][]

#### 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;
    
    public class Factory {
    	private int factory_id;
    	private String name;
    	
    	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 #####

#### 第四步：创建Hibernate.cfg.xml文件 ####

<?xml version='1.0' encoding='UTF-8'?>
    <!DOCTYPE hibernate-configuration PUBLIC
              "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
              "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
    
    <hibernate-configuration>
    	<session-factory>
    		<property name="myeclipse.connection.profile">register</property>
    		<property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
    		<property name="connection.password">root</property>
    		<property name="connection.username">root</property>
    		<property name="connection.url">jdbc:mysql://localhost:3306/register</property>
    		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
    		<property name="show_sql">true</property>
    		<property name="hbm2ddl.auto">update</property>
    	<property name="javax.persistence.validation.mode">none</property>
    		<mapping resource="com/dwx/entity/Factory.hbm.xml"/>
    		<mapping resource="com/dwx/entity/Product.hbm.xml"/>
    	</session-factory>
    </hibernate-configuration>

#### 第五步：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;
    	}
    
    }

#### 第六步：创建测试类 ####

package com.dwx.bz;
    
    import java.util.Iterator;
    import java.util.List;
    
    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{
    			Factory factory=new Factory();
    			factory.setName("清华大学出版社");
    			Product product=new Product();
    			product.setName("java web从入门到精通");
    			product.setPrice(79.00);
    			Product product1=new Product();
    			product1.setName("struts+hibernate+spring整合开发");
    			product1.setPrice(89.00);
    			product.setFactory(factory);
    			product1.setFactory(factory);
    			session=HibernateSessionFactory.getSession();
    			tx=session.beginTransaction();
    			session.save(product);
    			session.save(product1);			
    			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<Product>list=session.createQuery("from Product").list();
    		for(Iterator it=list.iterator();it.hasNext();){
      			Product pro=(Product)it.next();
      			System.out.println(pro.getName()+","+pro.getPrice()+","+pro.getFactory().getName());
      		}
      		HibernateSessionFactory.closeSession();
    	}
    }

#### 效果： ####

![20180524100555851][]

[20180524095754206]: /images/20220524/a3c2e1281a6d40d4a15e57f6cb832c74.png
[20180524095822400]: /images/20220524/09d6988e76864d3494c1dc8346a64f79.png
[20180524100555851]: /images/20220524/c194016757764fb1938347ccd9a94339.png