package com.fdy.oa.web;
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.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.fdy.oa.utils.HibernateUtils;
public class SessionFilter implements Filter {
      public void init(FilterConfig arg0) throws ServletException {
            try {
                  Class.forName("com.fdy.oa.utils.HibernateUtils");// 类加载时就加载了配置文件.
            } catch (ClassNotFoundException e) {
                  e.printStackTrace();
            }
      }
      public void destroy() {
      }
      public void doFilter(ServletRequest req, ServletResponse res,
      FilterChain chain) throws IOException, ServletException {
            Session session = null;
            try {
                  session = HibernateUtils.getSession();// 取到当前线程的session.
                  Transaction tx = session.beginTransaction();
                  chain.doFilter(req, res);
                  tx.commit();
            } catch (HibernateException e) {
                  session.beginTransaction().rollback();
                  e.printStackTrace();
            } finally {
            HibernateUtils.close();// 多线程条件下,如果不把session放入threadlocal中,你所操作的session可能不是之前的session.
      }
}
}

package com.fdy.oa.utils;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
public class HibernateUtils {
      private static Configuration cfg;
      private static SessionFactory factory;
      private static ThreadLocal<Session> local;
      static {
            cfg = new Configuration().configure("hibernate_mysql.cfg.xml");
            factory = cfg.buildSessionFactory();
            local = new ThreadLocal<Session>();
      }
      public static Session getSession() {
            if (local.get() == null) {
                  local.set(factory.openSession());
            }
            return local.get();
      }
      public static void close() {
            if (local.get() != null && local.get().isOpen()) {
                  local.get().close();
                  local.set(null);
            }
      }
}