HibernateTemplate使用之手工管理Session和Transaction

大多数人在第一次使用HibernateTemplate时都很好奇，不需要自己关闭Hibernate Session。如果在需要使用事务的情况一般使用spring配置TransactionProxyFactoryBean用AOP方式实现，还有就是使用HibernateTemplate的execute(HibernateCallback action)方法，构造一个匿名类实现HibernateCallback接口的Object doInHibernate(Session session)方法。使用前一种方法需要使用spring IOC，后一种代码因为使用匿名类，如果有较多逻辑代码显得难看、不清晰。是否还有其他使用HibernateTemplate的简单方法呢。
查看HibernateTemplate源码发现，如果不存在事务，每次执行HibernateTemplate方法都会取得新Session，执行完数据库操作后再关闭Session。虽说不是每次都是真正开关数据库连接，但总感觉这样做不好。我们需要即使多次执行HibernateTemplate中方法是用的同一个Session，这样既不浪费资源，也可以自己手工管理事务。现在就来写一个工具类模拟OpenSessionInView模式和HibernateTransactionManager功能

import org.hibernate.FlushMode;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.springframework.orm.hibernate3.HibernateTemplate;
import org.springframework.orm.hibernate3.SessionFactoryUtils;
import org.springframework.orm.hibernate3.SessionHolder;
import org.springframework.transaction.support.TransactionSynchronizationManager;
import org.springframework.util.Assert;

public class HibernateSessionUtils{

	private static final ThreadLocal sessionFactoryLocal = new ThreadLocal();

	public static void getSession(SessionFactory sessionFactory){
		getSession(sessionFactory,null);
	}

	public static void getSession(SessionFactory sessionFactory,FlushMode flushMode){
		if (TransactionSynchronizationManager.hasResource(sessionFactory))return;
		Session session = SessionFactoryUtils.getSession(sessionFactory, true);
		if (flushMode != null) {
			session.setFlushMode(flushMode);
		}
		TransactionSynchronizationManager.bindResource(sessionFactory, new SessionHolder(session));
		sessionFactoryLocal.set(sessionFactory);
	}

	public static void beginTransaction(){
		SessionFactory sessionFactory = (SessionFactory) sessionFactoryLocal.get();
		Assert.state(sessionFactory != null,"No existing sessionFactory found for thread");
		SessionHolder sessionHolder = (SessionHolder)TransactionSynchronizationManager.getResource(sessionFactory);
		Assert.state(sessionHolder != null,"No existing session found for transaction");
		Transaction transaction = sessionHolder.getTransaction();
		Assert.state(transaction == null,"transaction already found for transaction");
		transaction = sessionHolder.getSession().beginTransaction();
		transaction.begin();
		sessionHolder.setTransaction(transaction);
	}
	
	public static void commit(){
		commit(true);
	}
	public static void commit(boolean autoClose){
		SessionFactory sessionFactory = (SessionFactory) sessionFactoryLocal.get();
		Assert.state(sessionFactory != null,"No existing sessionFactory found for thread");
	    SessionHolder sessionHolder = (SessionHolder)TransactionSynchronizationManager.getResource(sessionFactory);
		Assert.state(sessionHolder != null,"No existing session found for transaction");
		Transaction transaction = sessionHolder.getTransaction();
		Assert.state(transaction != null,"No transaction found for transaction");
		transaction.commit();
		sessionHolder.setTransaction(null);
		if(autoClose)
			closeSession();
	}

	public static void rollback(){
		SessionFactory sessionFactory = (SessionFactory) sessionFactoryLocal.get();
		Assert.state(sessionFactory != null,"No existing sessionFactory found for thread");
		SessionHolder sessionHolder = (SessionHolder)TransactionSynchronizationManager.getResource(sessionFactory);
		Assert.state(sessionHolder != null,"No existing session found for transaction");
		Transaction transaction = sessionHolder.getTransaction();
		Assert.state(transaction != null,"No transaction found for transaction");
		transaction.rollback();
		sessionHolder.setTransaction(null);
	}

	public static void closeSession(){
		SessionFactory sessionFactory = (SessionFactory) sessionFactoryLocal.get();
		if(sessionFactory == null)return;
		SessionHolder sessionHolder = (SessionHolder) TransactionSynchronizationManager.unbindResource(sessionFactory);
		if(sessionHolder != null){
			Transaction transaction = sessionHolder.getTransaction();
			Assert.state(transaction == null,"Transaction found for session");
		}
		SessionFactoryUtils.closeSession(sessionHolder.getSession());
		sessionFactoryLocal.set(null);
	}

}

使用示例

public static void main(String[] args) {
		SessionFactory sessionFactory = new Configuration().configure().buildSessionFactory();
		HibernateTemplate template = new HibernateTemplate(sessionFactory);
		HibernateSessionUtils.getSession(sessionFactory);
		//do any thing
		template.find("....");
		HibernateSessionUtils.beginTransaction();
		template.save(null);
		HibernateSessionUtils.commit();
		HibernateSessionUtils.closeSession();
	}

编写测试代码或少量代码可以采用这种方式，如果是真正应用的话还是使用Spring IOC和AOP比较好，不推荐这种手工方式

评论

2 楼 left405 2009-02-20  

好东西, 收藏了.

1 楼 taupo 2008-06-05  

我们需要即使多次执行HibernateTemplate中方法是用的同一个Session，这样既不浪费资源，也可以自己手工管理事务

这个想法我觉得很好，但是一般都有事务的存在，所以我觉得楼主的这个实用性不高，呵呵