解析下HibernateSessionFactory.java

package org.xmh.db;



import org.hibernate.HibernateException;

import org.hibernate.Session;

import org.hibernate.cfg.Configuration;



/**

 * Configures and provides access to Hibernate sessions, tied to the

 * current thread of execution.  Follows the Thread Local Session

 * pattern, see {@link http://hibernate.org/42.html }.

 */

public class HibernateSessionFactory {



    /** 

     * Location of hibernate.cfg.xml file.

     * Location should be on the classpath as Hibernate uses  

     * #resourceAsStream style lookup for its configuration file. 

     * The default classpath location of the hibernate config file is 

     * in the default package. Use #setConfigFile() to update 

     * the location of the configuration file for the current session.   

     */

    private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";

	private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();

    private  static Configuration configuration = new Configuration();

    private static org.hibernate.SessionFactory sessionFactory;

    private static String configFile = CONFIG_FILE_LOCATION;



	static {

    	try {

			configuration.configure(configFile);

			sessionFactory = configuration.buildSessionFactory();

		} catch (Exception e) {

			System.err

					.println("%%%% Error Creating SessionFactory %%%%");

			e.printStackTrace();

		}

    }

    private HibernateSessionFactory() {

    }

	

	/**

     * Returns the ThreadLocal Session instance.  Lazy initialize

     * the <code>SessionFactory</code> if needed.

     *

     *  @return Session

     *  @throws HibernateException

     */

    public static Session getSession() throws HibernateException {

        Session session = (Session) threadLocal.get();



		if (session == null || !session.isOpen()) {

			if (sessionFactory == null) {

				rebuildSessionFactory();

			}

			session = (sessionFactory != null) ? sessionFactory.openSession()

					: null;

			threadLocal.set(session);

		}



        return session;

    }



	/**

     *  Rebuild hibernate session factory

     *

     */

	public static void rebuildSessionFactory() {

		try {

			configuration.configure(configFile);

			sessionFactory = configuration.buildSessionFactory();

		} catch (Exception e) {

			System.err

					.println("%%%% Error Creating SessionFactory %%%%");

			e.printStackTrace();

		}

	}



	/**

     *  Close the single hibernate session instance.

     *

     *  @throws HibernateException

     */

    public static void closeSession() throws HibernateException {

        Session session = (Session) threadLocal.get();

        threadLocal.set(null);



        if (session != null) {

            session.close();

        }

    }



	/**

     *  return session factory

     *

     */

	public static org.hibernate.SessionFactory getSessionFactory() {

		return sessionFactory;

	}



	/**

     *  return session factory

     *

     *	session factory will be rebuilded in the next call

     */

	public static void setConfigFile(String configFile) {

		HibernateSessionFactory.configFile = configFile;

		sessionFactory = null;

	}



	/**

     *  return hibernate configuration

     *

     */

	public static Configuration getConfiguration() {

		return configuration;

	}



}

学习hibernate，我现在想从自己手上的一个hibernate+spring的web实例去解读，零基础开始学习hibernate+spring

只要能尽快学会使用，或者能给我提供帮助的，我都给分，
我的疑问：
这个文件是自动生成还是手写的，自动生成的话，请给我详细说说如何自动生成，对于我来讲，参照这个自己也是手敲，
如果是手写，能跟我注释下，让我看明白也行，
关于这个文件的用途以及用到的要点，或者如何去理解，也行，回头我看看大家的意见，谢谢大家。


第二个问题：
String sqlquery = "from Person ";
//该方法用来打印Person表中的所有的用户名
//该语句用来通过HibernateTemplate来查询Person表中的所有记录
List list = this.getHibernateTemplate().find(sqlquery);
System.out.println("表中的数据有： " + list.size() + " 条");
...

List list = this.getHibernateTemplate().find(sqlquery);


跟我讲一下,getHibernateTemplate().find("from Person")
什么意思?讲具体点.