hibernate session 过滤器控制

最近做一个公司项目的Demo，使用技术为jsp+dwr+hibernate,因为该Demo中所用的表多，有一对一，一对多和多对一的关系，所以利用hibernate的延迟加载（lazy="true"）对性能的提高相当重要，但随之带来的session管理更为重要，弄不好常出现延迟加载异常，在这里我利用了Filter 来处理session的close的，相关代码如下：

 

1.HibernateSessionFactory.java(Eclipse自动生成，通过ThreadLocal 将session的非线程安全变成安全)

import org.apache.log4j.Logger;
import org.hibernate.HibernateException;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;


public class HibernateSessionFactory {

    private static final Logger log = Logger.getLogger(SessionFactory.class) ;
	private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
    private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
    private static Configuration configuration = new Configuration();
    private static org.hibernate.SessionFactory sessionFactory;
    private static String configFile = CONFIG_FILE_LOCATION;

	static {
    	try {
			configuration.configure(configFile);
			sessionFactory = configuration.buildSessionFactory();
		} catch (Exception e) {
			
			log.error(" error creating sessionFactory") ;
			e.printStackTrace();
		}
    }
    public HibernateSessionFactory() {
    }
	

    public static Session getSession() throws HibernateException {
    	log.info("getSession is run") ;
    	
        Session session = (Session) threadLocal.get();
		if (session == null || !session.isOpen()) {
			log.info("SessionFactory.getSession() session is null or close") ;
			if (sessionFactory == null) {
				log.info("SessionFactory.getSession() rebuildSessionFactory() is running") ;
				rebuildSessionFactory();
			} 
			session = (sessionFactory != null) ? sessionFactory.openSession(): null;
			threadLocal.set(session);
		}

        return session;
    }


	public static void rebuildSessionFactory() {
		log.info("rebuildSessionFactory is run") ;
		try {
			configuration.configure(configFile);
			sessionFactory = configuration.buildSessionFactory();
		} catch (Exception e) {
			log.error("erro creating sessionFactory") ;
			e.printStackTrace();
		}
	}


    public static void closeSession() throws HibernateException {
    	log.info("closeSession is run") ;
    	
        Session session = (Session) threadLocal.get();
        threadLocal.set(null);
        if (session != null) {
        	log.info("SessionFactory.closeSession() session is not null") ;
        	if(!session.isOpen()){
        		System.out.println("该 session 已经关闭") ;
        	}
            session.close();
        }
    }


	public static org.hibernate.SessionFactory getSessionFactory() {
		return sessionFactory;
	}


	public static void setConfigFile(String configFile) {
		SessionFactory.configFile = configFile;
		sessionFactory = null;
	}


	public static Configuration getConfiguration() {
		return configuration;
	}
	


}

 HibernateSessioniFactory主要负责session的开和关。

 

2.HibernateSessionFilter(要编写的过滤器，主要处理session的关闭)

import java.io.IOException;


import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.ad.session.HibernateSessionFactory;

public class HibernateSessionFilter implements Filter {  
    private static final Log log = LogFactory.getLog(HibernateSessionFilter.class);  
    
   
      @Override
	public void init(FilterConfig filterConfig) throws ServletException {
		System.out.println("HibernateSessionFilter is end") ;
	} 
  
   @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1,  
            FilterChain chain) throws IOException, ServletException {  
        log.debug("HibernateSessionFilter start");  
        
        try{  
            //request 之前要处理的代码
            chain.doFilter(arg0, arg1);     
           //response之后要要处理的代码    
           
        }catch (Exception e) {  
            e.printStackTrace();             
        }   finally{          
            HibernateSessionFactory.closeSession();            
        }  
  
    }
  
     
   @Override
     public void destroy() {     
       System.out.println("HibernateSessionFilter is start") ;
     }  
  
}

  该过滤器只处理session的关闭，似乎有点浪费了，在这也可以加上字符集的处理。

  Filter运行原理(个人认为，有误请多指教)：首先建立一个过滤类，需继承Filter接口，必须实现三个方法：

  init：服务器启动时运行该方法，运行期间不执行；

 doFilter：运行期间执行，其作用是request之前要做那些工作，response之后(即服务器将内容全部发回View层后)

               要做那些工作。每次访问服务器都会执行doFilter方法

 destroy：服务器终止时运行。

 

3. 在web.xml中的配置如下：

        <filter>
		<filter-name>hibernateSession</filter-name>
		<filter-class>
			com.c35.ad.filter.HibernateSessionFilter
		</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>hibernateSession</filter-name>
		<url-pattern>/*</url-pattern><!-- 过滤所有发回服务器的请求-->
	</filter-mapping>

 

  4.dao(demo中的UserDao)

 

public class UserDao  implements BaseDao {

	private static final Logger log = Logger.getLogger(UserDao.class);
    
	private  Session session  ;
   
	public UserDao(){
       log.info("UserDao construct is running") ;    
    	   session = SessionFactory.getSession() ;
    }
    

	@Override
	public boolean save(Object o) {
		log.info("UserDao save is running ");
		boolean flag = false ;	
		Transaction tran = null;	
		try {		
			tran = session.beginTransaction();
			session.save(o);
			tran.commit();
			flag = true ;
		} catch (Exception e) {
			log.error("error save user");
			flag = false ;
			if (tran != null) {
				try {
					tran.rollback();
				} catch (HibernateException e1) {
					log.error("save Transaction rollback is error "+e1.getMessage()) ;
				}
			}
			e.printStackTrace();
		}finally{
			//session.close() ;//这里就不需要在关闭session直接交给filter来处理
		}
		return flag ;
	}
}

    以上是本人的学习总结，有误之处请多多指教，希望对刚学hibernate的同志们有所帮助。

 

 

 

评论

1 楼 ariyue 2008-11-07  

高手，学习中！