Spring, JBPM持久化系列--摆脱LazyInitializationException 二

Spring, Springmodules, JBPM持久化集成--摆脱
LazyInitializationException(Part2)
Spring, Springmodules, JBPM持久化集成理解系列三
【本系列如需转载，请注明作者及出处】


到此，如果有朋友还是比较清醒的话，应该还会有疑问，在OpenSessionInViewFilter里如果是isSingleSession为true，并没有看到session的关闭，到底是在什么地方关闭了呢？它其实是在OpenSessionInViewInterceptor里关闭了的。

 

public void afterCompletion(WebRequest request, Exception ex) throws DataAccessException {
		String participateAttributeName = getParticipateAttributeName();
		Integer count = (Integer) request.getAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
		if (count != null) {
			// Do not modify the Session: just clear the marker.
			if (count.intValue() > 1) {
				request.setAttribute(participateAttributeName, new Integer(count.intValue() - 1), WebRequest.SCOPE_REQUEST);
			}
			else {
				request.removeAttribute(participateAttributeName, WebRequest.SCOPE_REQUEST);
			}
		}
		else {
			if (isSingleSession()) {
				// single session mode
				SessionHolder sessionHolder =
						(SessionHolder) TransactionSynchronizationManager.unbindResource(getSessionFactory());
				logger.debug("Closing single Hibernate Session in OpenSessionInViewInterceptor");
				SessionFactoryUtils.closeSession(sessionHolder.getSession());
			}
			else {
				// deferred close mode
				SessionFactoryUtils.processDeferredClose(getSessionFactory());
			}
		}
	}

 

 

 

总结一下：

OpenSessionInViewFilter首先会确保sessionFactory的存在，

如果启用了session延迟关闭策略，也就是isSingleSession为false，session的创建和打开会在HibernateTemplate的execute里发生，而关闭会统一在OpenSessionInViewFilter返回时。

 

如果isSingleSession为true时，session的打开会在OpenSessionInViewFilter里或者之前的某个时候，而关闭会在OpenSessionInViewInterceptor里。

 

这样我们就可用自己在Junit或者其他应用场景使用延迟关闭策略来使我们的程序收益。以下附带前面篇章提及到的BaseTestCase，如果存在SessionFactory，则激活延迟关闭session策略。各位可用参考使用。

 

package com.cabernet;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.FlushMode;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.springframework.dao.DataAccessResourceFailureException;
import org.springframework.orm.hibernate3.SessionFactoryUtils;
import org.springframework.orm.hibernate3.SessionHolder;
import org.springframework.test.AbstractDependencyInjectionSpringContextTests;
import org.springframework.transaction.support.TransactionSynchronizationManager;

/**
 * Supports OpenSessionInViewFilter like Hibernate Lazy-loading when
 * SessionFactory is present
 * 
 * @author ginge
 * 
 * @see OpenSessionInViewFilter
 */
public class BaseTestCase extends AbstractDependencyInjectionSpringContextTests
{
	protected Log				log			= LogFactory.getLog(this.getClass());

	private FlushMode			flushMode	= FlushMode.MANUAL;

	protected SessionFactory	sessionFactory;

	@Override
	protected void prepareTestInstance() throws Exception
	{
		// TODO Auto-generated method stub
		super.prepareTestInstance();

		if (isSessionFactoryPresent())
		{
			afterSessionFactorySet();
			SessionFactoryUtils.initDeferredClose(sessionFactory);
			TransactionSynchronizationManager.bindResource(sessionFactory, new SessionHolder(this.getSession()));
		}
	}

	@Override
	protected void onTearDown() throws Exception
	{
		// TODO Auto-generated method stub

		if (isSessionFactoryPresent())
		{
			SessionFactoryUtils.processDeferredClose(sessionFactory);
			TransactionSynchronizationManager.unbindResource(sessionFactory);
		}

		super.onTearDown();
	}

	private boolean isSessionFactoryPresent()
	{
		return this.sessionFactory != null;
	}

	protected void afterSessionFactorySet()
	{

	}

	public SessionFactory getSessionFactory()
	{
		return sessionFactory;
	}

	public void setSessionFactory(SessionFactory sessionFactory)
	{
		this.sessionFactory = sessionFactory;
	}

	@Override
	protected String[] getConfigLocations()
	{
		return new String[] { "classpath*:applicationContext-resources.xml" };
	}

	protected Session getSession() throws DataAccessResourceFailureException
	{
		Session session = SessionFactoryUtils.getSession(sessionFactory, true);
		FlushMode flushMode = getFlushMode();
		if (flushMode != null)
		{
			session.setFlushMode(flushMode);
		}
		return session;
	}

	private FlushMode getFlushMode()
	{
		return this.flushMode;
	}
}

 

 

 

 

到了这个时刻，我们回到Jbpm跟Springmodules, Spring的持久化集成上来，虽然Jbpm本身提供了JbpmContextFilter，它的功能是在Filter开始打开JbpmContext，Filter返回时关闭JbpmContext。但是在前面的篇章中，我们知道JbpmTemplate中会在操作开始前注入session。因此，使用了OpenSessionInViewFilter和JbpmTemplate之后，JbpmContextFilter将会英雄无用武之地。这个OpenSessionInViewFilter必须配置在其他Filter之前以确保在进入其他Filter之前激活延迟关闭策略或者绑定Session到当前线程中。

 

 

（完结）

评论

1 楼 netment 2008-03-05  

仰慕ing