hibernate.java

hibernate处理缓存.提高运行速度.

package com.holpe.database;

/**
 * <p>Title: </p>
 *
 * <p>Description: </p>
 *
 * <p>Copyright: Copyright (c) 2008</p>
 *
 * <p>Company:holpe </p>
 *
 * @author liuxb
 * @version 1.0
 */
import java.io.File;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

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

/**
 * Hibernate的操作接口
 */
public class Hibernate {

        private final static Log log = LogFactory.getLog(Hibernate.class);
       // public static final ThreadLocal session = new ThreadLocal();;
        private String hibernate_cfg;
        private SessionFactory sessionFactory;
        private ThreadLocal sessions;
        private ThreadLocal transactions;

        /**
         * Initialize the hibernate environment
         * @param hibernate_cfg
         * @throws MalformedURLException
         */
        public final static Hibernate init(String hibernate_cfg){
                return new Hibernate(hibernate_cfg);
        }

        /**
         * 根据输入的配置文件初始化Hibernate
         * @param cfg_path
         */
        private Hibernate(String cfg_path){
                sessions = new ThreadLocal();
                transactions = new ThreadLocal();
                Configuration cfg = new Configuration().configure(new File(cfg_path));
                sessionFactory = cfg.buildSessionFactory();
                this.hibernate_cfg = cfg_path;
        }

        /**
         * 返回对应的Hibernate配置文件的路径
         * @return
         */
        public String getHibernateConfig() {
                return hibernate_cfg;
        }

        /**
         * Get a instance of hibernate's session
         * @return
         * @throws HibernateException
         */
        public Session getSession(){
                if(sessions == null)
                        return null;

                Session ssn = (Session)sessions.get();
                if (ssn == null) {
                        ssn = sessionFactory.openSession();
                        sessions.set(ssn);
                }


                return ssn;
        }

        /**
         * Closes the Session local to the thread.
         */
        public void closeSession(){
                if(sessions == null)
                        return;
                // Would be written as a no-op in an EJB container with CMT
                Session ssn = (Session)sessions.get();
                if(ssn == null)
                        return;
                else if(ssn.isOpen())
                        ssn.close();

                sessions.set(null);
        }

        /**
         * Start a new database transaction.
         */
        public void beginTransaction(){
                if(transactions == null)
                        return;
                // Would be written as a no-op in an EJB container with CMT
                Transaction tx = (Transaction)transactions.get();
                if (tx == null || tx.wasCommitted() || tx.wasRolledBack()) {
                        Session ssn = (Session)sessions.get();
                        if(ssn == null){
                                ssn = getSession();
                                tx = ssn.beginTransaction();
                                transactions.set(tx);
                        }
                        else if(ssn != null){
                                tx = ssn.beginTransaction();
                                transactions.set(tx);
                        }
                }
                else{
                        if(tx!=null && log.isWarnEnabled())
                                log.warn("Trying to begin a exist transaction, nothing to do.", new Exception());
                }
        }

        /**
         * Commit the database transaction.
         */
        public void commit(){
                if(transactions == null)
                        return;
                // Would be written as a no-op in an EJB container with CMT
                Transaction tx = (Transaction)transactions.get();
                if (tx != null && !tx.wasCommitted() && !tx.wasRolledBack()) {
                        tx.commit();
                }
                else{
                        if(tx!=null && log.isWarnEnabled())
                                log.warn("Trying to commit the uncommitable transaction, nothing to do.");
                }
                if(tx!=null)
                        transactions.set(null);
        }

        /**
         * Rollback the database transaction.
         */
        public void rollback(){
                if(transactions == null)
                        return;
                Transaction tx = (Transaction)transactions.get();
                transactions.set(null);
                if (tx != null && !tx.wasCommitted() && !tx.wasRolledBack()) {
                        tx.rollback();
                }
                else{
                        if(tx!=null && log.isWarnEnabled())
                                log.warn("Trying to rollback the unrollbackable transaction, nothing to do.");
                }
        }



        /**
         * 释放所有Hibernate占用的资源
         * @see com.liusoft.dlog4j.servlet.DLOG_ActionServlet#destroy()
         */
        public void destroy(){
                if(sessionFactory!=null){
                        sessionFactory.close();
                        sessionFactory = null;
                }
                sessions = null;
                transactions = null;
                if(log.isWarnEnabled())
                        log.warn("Hibernate("+hibernate_cfg+") was destroy successfully, all of sessions were closed.");
        }

}