Hibernate 提供session的工具类HibernateUtils

package cn.itcast.utils;

import java.sql.Connection;
import java.sql.SQLException;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.jdbc.Work;

public class HibernateUtils {

    private static Configuration cfg;
    private static SessionFactory sessionFactory;
    private static ThreadLocal<Session> threadLocal;

    static {
        cfg = new Configuration();//一个加载器
        cfg.configure();//加载默认位置核心配置文件
        sessionFactory = cfg.buildSessionFactory();//一个session工厂
        threadLocal=new ThreadLocal<Session>();
    }

    public static Session getSession() {

        Session session=threadLocal.get();
        if(session==null) {

            session = sessionFactory.openSession();//创建session
            threadLocal.set(session);
            session=threadLocal.get();
        }
        return session;
    }

    public static void main(String[] args) {
        Session session = getSession();
        session.doWork(new Work() {

            @Override
            public void execute(Connection con) throws SQLException {
                // TODO Auto-generated method stub
                System.out.println(con);

            }});
    }
}