HibernateUtil.java

package cn.jsprun;

import java.io.FileInputStream;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.util.Properties;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
/**
 * Hibernate数据库连接工具
 * 参考：JspRun 源码
 * @author SUN
 *
 */
public final class HibernateUtil { // final 不能被继承
	/** sf 只提供类内部访问,且只有一份实例。  */
	private static SessionFactory sessionFactory = null;
	
	private static String message = null;
	
	/**
	 * 加载到内存时第一个被初始化，且只初始化一次。
	 */
	static {
		buildSessionFactory();	// 构建SF
	}

	/**
	 * 构建数据库全局会话工厂对象
	 */
	public static synchronized void buildSessionFactory() {
		
		// 检查sf不为null才去构建sf对象
		if (sessionFactory == null) { // true 为null
			try {

				// 读取数据库连接配置信息
				Properties properties = new Properties();
				InputStream fis = new FileInputStream("D:/workspaceee/netzz/src/config.properties");
				properties.load(fis);
				fis.close();
				String dbhost = properties.getProperty("dbhost");
				String dbport = properties.getProperty("dbport");
				String dbname = properties.getProperty("dbname");
				String dbuser = properties.getProperty("dbuser");
				String dbpw = properties.getProperty("dbpw");

				// 检查数据库配置信息是否可以连接
				if (mysql_connect(dbhost, dbport, dbname, dbuser, dbpw)) { // true 可用
					
					// 创建并设置hibernate属性对象
					Properties extraProperties = new Properties();
					extraProperties.setProperty("hibernate.connection.url", 
							"jdbc:mysql://" + dbhost + ":" + dbport + "/" + dbname + "?zeroDateTimeBehavior=convertToNull");
					extraProperties.setProperty("hibernate.connection.username", dbuser);
					extraProperties.setProperty("hibernate.connection.password", dbpw);

					// 构建SessionFactory
					Configuration configuration = new Configuration(); // 创建hibernate配置对象
					configuration = configuration.configure("hibernate.cfg.xml");	// 获得hibernate配置文件
					configuration = configuration.addProperties(extraProperties);	// 添加属性对象
					sessionFactory = configuration.buildSessionFactory();	// 构建SF数据库会话工厂对象

					// 释放不在使用的资源
					extraProperties = null;	
					configuration = null;
				}
				properties = null;
			} catch (Exception e) {
				message = "Create sessionFactory Exception! " + e.getMessage();
			}
		}
	}

	/**
	 * 获得sf
	 * @return
	 */
	public static SessionFactory getSessionFactory() {
		if (sessionFactory == null) {
			buildSessionFactory();
		}
		return sessionFactory;
	}

	/**
	 * 获得session
	 * @return
	 */
	public static Session getSession() {
		if (sessionFactory == null) {
			buildSessionFactory();
		}
		return sessionFactory.getCurrentSession();
	}

	/**
	 * 重新构建sf
	 */
	public static void rebuildSessionFactory() {
		try {
			Properties properties = new Properties();
			InputStream fis = new FileInputStream("c:/config.properties");
			properties.load(fis);
			fis.close();
			String dbhost = properties.getProperty("dbhost");
			String dbport = properties.getProperty("dbport");
			String dbname = properties.getProperty("dbname");
			String dbuser = properties.getProperty("dbuser");
			String dbpw = properties.getProperty("dbpw");
			if (mysql_connect(dbhost, dbport, dbname, dbuser, dbpw)) {
				Properties extraProperties = new Properties();
				extraProperties.setProperty("hibernate.connection.url", "jdbc:mysql://" + dbhost + ":" + dbport + "/" + dbname
						+ "?zeroDateTimeBehavior=convertToNull");
				extraProperties.setProperty("hibernate.connection.username", dbuser);
				extraProperties.setProperty("hibernate.connection.password", dbpw);
				Configuration configuration = new Configuration();
				configuration = configuration.configure("hibernate.cfg.xml");
				configuration = configuration.addProperties(extraProperties);
				sessionFactory = configuration.buildSessionFactory();
				extraProperties = null;
				configuration = null;
			}
			properties = null;
		} catch (Exception e) {