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：/article/8562667.html

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<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;
}

}