In some special circumstances, we may be saved in the database connection information config.properties document, for example, make a install.jsp to modify config.properties documents, implementation of online information on the database configuration. At this time the database connection information stored in hibernate . cfg.xml not convenient. so should be saved to a separate properties file.

config.properties document reads as follows:

#数据库IP
dbhost = localhost

#端口号
dbport=3306

#用户名
dbuser = root

#密码
dbpw = 1234

#数据库名
dbname = test

No database configuration file hibernate.cfg.xml information, as follows:

<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
	<session-factory >
		<property name="show_sql">true</property>
		<property name="hibernate.hbm2ddl.auto">update</property>
		
		<property name="hibernate.dialect">org.hibernate.dialect.MySQLInnoDBDialect</property>
		<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
		
		<!--   注释了, 不起作用
		//<property name="hibernate.connection.url">jdbc:mysql:///test</property>
		//<property name="hibernate.connection.username">root</property>
		//<property name="hibernate.connection.password">1234</property>
	    -->
	
	<mapping resource="dao/po/User.hbm.xml"/>
	</session-factory>
</hibernate-configuration>

We do a combination of:

package dao;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.Properties;

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

/**
 * 这是一个工具类, 快速取得session
 * 
 */
public class HibernateUtil
{
	static SessionFactory	sessionFactory	= null;

	static
	{
		try
		{

			final String path = URLDecoder.decode(Thread.currentThread().getContextClassLoader().getResource(
					"config.properties").getPath(), "UTF-8"); //config.properties保存的真实路径
			final Properties properties = new Properties();
			final InputStream fis = new FileInputStream(path); //config.properties 文件对象，里面有数据库的连接信息，
			properties.load(fis);
			fis.close(); //关流
			final String dbhost = properties.getProperty("dbhost"); //数据库IP(从config.properties读)
			final String dbport = properties.getProperty("dbport"); //端口(从config.properties读)
			final String dbname = properties.getProperty("dbname"); //数据库名(从config.properties读)
			final String dbuser = properties.getProperty("dbuser"); //用户名(从config.properties读)
			final String dbpw = properties.getProperty("dbpw"); //密码(从config.properties读)

			final 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);

			final Configuration cfg = new Configuration();
			cfg.addProperties(extraProperties);
			cfg.configure("hibernate.cfg.xml"); //路径可以改变
			sessionFactory = cfg.buildSessionFactory();
		}
		catch (final UnsupportedEncodingException e)
		{
			//不支持字符编码。
			e.printStackTrace();
		}
		catch (final FileNotFoundException e)
		{
			//config.properties文件没找到
			e.printStackTrace();
		}
		catch (final HibernateException e)
		{
			//cfg.configure("hibernate.cfg.xml");时异常
			e.printStackTrace();
		}
		catch (final Exception e)
		{
			//创建SessionFactory 异常
			e.printStackTrace();
		}
	}

	public static SessionFactory getSessionFactory()
	{
		return sessionFactory;
	}

	/**
	 * 取得session
	 * 
	 * @return session
	 */
	public static Session getSeesion()
	{
		return sessionFactory.openSession();
	}
}