Hibernate中使用openSessionInView代替lazy="false"的方法

最新推荐文章于 2021-06-20 13:41:12 发布

原创最新推荐文章于 2021-06-20 13:41:12 发布 · 514 阅读

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本文介绍了一个使用Hibernate进行事务管理的过滤器实现，展示了如何在Servlet过滤器中集成Hibernate，并实现自动的事务开启、提交和回滚。

Filter:

package com.dqd.filter;

import java.io.IOException;
import java.io.PrintWriter;

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 javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.hibernate.Session;
import org.hibernate.Transaction;

import com.dqd.util.HibernateUtil;

public class MyFilter extends HttpServlet implements Filter {

	@Override
	public void doFilter(ServletRequest arg0, ServletResponse arg1,
			FilterChain arg2) throws IOException, ServletException {
			Session session = null;
			Transaction tx = null;
			try{
				session = HibernateUtil.getCurrentSession();
				tx = session.beginTransaction();
				arg2.doFilter(arg0, arg1);
				//提交！！！
				tx.commit();
				
			}catch(Exception e){
				if(tx!=null){
					tx.rollback();
				}
				e.printStackTrace();
			}finally{
				//这里的关闭不能像之前那样s!=null&&s.isopen()简单的去关闭,这里通过一个方法去关闭
				//还得让ThreadLocal.set(null)
				HibernateUtil.closeCurrentSession();
			}
			
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
		// TODO Auto-generated method stub

	}

	public MyFilter() {
		super();
	}
	public void destroy() {
		super.destroy(); // Just puts "destroy" string in log
		// Put your code here
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		out.println("<HTML>");
		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println("  <BODY>");
		out.print("    This is ");
		out.print(this.getClass());
		out.println(", using the GET method");
		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

			this.doGet(request, response);
	}

	public void init() throws ServletException {
		// Put your code here
	}

}

在hibernate工具类中做出相应的变化，不再使用事物和异常的捕捉（在Filter中已经实现了）

package com.dqd.util;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;

final public class HibernateUtil {
	private static SessionFactory sf = null;
	private static ThreadLocal<Session> tl = new ThreadLocal<Session>();
	private static ServiceRegistry sr= null;
	private static Configuration con =null;
	
	private HibernateUtil(){}
	static{
		con = new Configuration().configure();
		sr = new ServiceRegistryBuilder().applySettings(con.getProperties()).buildServiceRegistry();
		sf = con.buildSessionFactory(sr);
	}
	//获得全新的Session
	public static Session openSession(){
		return sf.openSession();
	}
	//获得和线程相关的Session
	public static Session getCurrentSession(){
		Session session = tl.get();
		if(session==null){
			session = sf.openSession();
			tl.set(session);
		}
		return session;
	}
	public static List excuteQuery(String hql){
		Session session = null;
		//因为动作会频繁的发生所以使用事物
		
		List list = null;
	
			session = HibernateUtil.getCurrentSession();
			
			list = session.createQuery(hql).list();
			
		return list;
	} 
	public static Object findId(Class clazz,java.io.Serializable id){
		Session session = null;
		//因为动作会频繁的发生所以使用事物
		
		List list = null;
		Object obj = null;
	
			session = HibernateUtil.getCurrentSession();
			obj = session.load(clazz, id);
		
		return obj;
	}
	public static void closeCurrentSession(){
		Session s = getCurrentSession();
		if(s!=null&&s.isOpen()){
			s.close();
			tl.set(null);
		}
	}
	
	//加强版的查询方式（防止注入漏洞）
	//在这里应该考虑到并发性的问题，我们的方法是静态的但是每次我们都会信声明一个session(session不是静态)，所以不会拥堵
	public static List excuteQuery(String hql,String[] para){
		
		Session s = null;
		List list = null;
		
			s = getCurrentSession();
			Query query = s.createQuery(hql);
			//判断是否有空串
			if(para!=null&¶.length>0){
				for(int i =0 ;i< para.length;++ i){
					query.setString(i, para[i]);
				}	
			}
			list = query.list();
		
		return list;
	}
}