Hibernate 核心的API

Configuration cfgConfiguration=new Configuration();
		SessionFactory s = cfgConfiguration.configure().buildSessionFactory();
		Session ss=s.openSession();
		ss.beginTransaction();
		ss.save(ip_List);
		ss.save(student);
		ss.getTransaction().commit();
		ss.close();
		s.close();

 

 

1.Configuration

用于获取hibernate的配置文件 默认文件名为hibernate.cfg.xml；也可以自己配置路径

通过configure()方法获取配置信息；

 

2.SessionFactory

session工厂类 用于获取Session对象 有两种获取方法：

a. openSession() 用于建立一个新的Session会话 需要Close

b. getCurrentSession 用于从上下文中获取一个会话 不存在 则建立新的会话（推荐)  上下文通常配置在Hibernate配置文件中，thread为从当前线程获取。

 

3.Session

一次数据库连接会话；数据库的sql操作都执行于Session会话中；不过所有处理都必须按照事务处理

a.session.beginTransaction() 开始事务

b.session.getTransaction().commit();提交事务

c.save(Object o) 插入操作

b.delete(Object o) 删除操作；所传的实体 必须有ID 否则会出异常

e.load(theClass, id) 查询操作    延迟化查询    再关闭事务之前调用查询到的对象时 才执行select操作/ 若事务关闭了 再调用实体 会有异常

get(theClass, id) 查询操作 立刻查询

 

f. update(Object o) 更新操作  

利用HQL 执行查询   注意操作的是具体的实体类 而不是表；org.hibernate.Query query=session.createQuery(hql);  //利用query接口实现查询

 详见：http://blog.csdn.net/zhuali_linkin/article/details/7273276

 

g. clear   清除缓存（session）中的所有持久化对象

h. flush   对缓存（session）中的对象做一次数据库提交

 

对象的三种状态

a  透明态 持久态 托管态

 

 

 

hibernate 常用的一个工厂类

package com.zhuxuli.HibernateSession;

import javax.persistence.Entity;
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 }.
 */
@Entity
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 threadLocal = new ThreadLocal();
    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 SessionFactory 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;
	}

}