Myeclipse生成的session是否需要手动关闭？

Question

看了几篇关于session关闭的文章，还是不能确定，初学hibernate3 不知道session是否需要手动关闭，没有用spring和其它的托管，web应用程序中
myeclipse生成的dao中的方法如下： 不知道是否需要在save方法里或查询的方法里加上
finally{
HibernateSessionFactory.closeSession();
}

如果不需要关闭的话，具体原因是什么呢？
public void save(Custinfo transientInstance) {
log.debug("saving WxGzjg instance");
try {
Transaction tran = null;
tran = (Transaction) getSession().beginTransaction();
getSession().save(transientInstance);
log.debug("save successful");
tran.commit();
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}

我用myeclipse6.5,hibernate3.0生成的SessionFactory 类如下：
package com.soft.hibernate;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;

/**

• 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 String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml"; private static final ThreadLocal threadLocal = new ThreadLocal(); private static Configuration configuration = new Configuration();
    private static org.hibernate.SessionFactory sessionFactory; private static String configFile = CONFIG_FILE_LOCATION;

  private static final Log log = LogFactory.getLog(HibernateSessionFactory.class);

  static {
  try {
  configuration.configure(configFile);
  sessionFactory = configuration.buildSessionFactory();
  } catch (Exception e) {
  log.info("Error Creating SessionFactory");
  System.err.println("Error Creating SessionFactory");
  e.printStackTrace();
  }
  }
  private HibernateSessionFactory() {
  }

  /**

  • Returns the ThreadLocal Session instance. Lazy initialize
  • the SessionFactory 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(configFile); sessionFactory = configuration.buildSessionFactory(); } catch (Exception e) { log.info("Error Creating SessionFactory"); 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 session factory *
  • session factory will be rebuilded in the next call */ public static void setConfigFile(String configFile) { HibernateSessionFactory.configFile = configFile; sessionFactory = null; }

  /**

  • return hibernate configuration * */ public static Configuration getConfiguration() { return configuration; }

}

Answer 1

当然需要关闭session.不关闭,服务器的资源会被严重浪费.

如果没有用到hibernate的lazy,那么就在查询结束的时候就关闭session
如果用到了lazy那么就用filter的方式关闭.

个人建议用完一个session就关闭一个session.像你这样刚接触hibernate,可能对于lzay还不太明白.你可以先学会用会hibernate,过段时间再去深入学习,用好hibernate,尤其是性能的优化.