Hibernate基于ThreadLocal管理Session过程解析

package com.yl.utils;

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

/**
 * hibernate工具类
 */
public class HibernateUtils {
  private static SessionFactory sessionFactory;
  private static ThreadLocal<Session> threadLocal=new ThreadLocal<Session>();

  static {
    //加载配置文件
    Configuration cig = new Configuration().configure();
    //创建工厂
    sessionFactory = cig.buildSessionFactory();
  }

  /**
   * 获取Session对象
   */
  public static Session getSession(){
    //判断threadlocal是否已经存在当前线程的Session，不存在才创建
    Session session=threadLocal.get();
    if (session==null){
      session=sessionFactory.openSession();
      threadLocal.set(session);
    }
    return session;
  }
  
  /**
   * 关闭session
   */
  public static void close() {
    Session session = threadLocal.get();
    if (session != null) {
      session.close();
    }
    threadLocal.set(null);
  }
}

package com.yl.utils;

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

/**
 * hibernate工具类
 */
public class HibernateUtils {
  private static SessionFactory sessionFactory;
  
  static {
    //加载配置文件
    Configuration cig = new Configuration().configure();
    //创建工厂
    sessionFactory = cig.buildSessionFactory();
  }

  /**
   * 获取Session对象
   */
  public static Session getSession(){
    return sessionFactory.getCurrentSession();
  }
}