文章援引自：http://www.cnblogs.com/eflylab/archive/2007/01/09/615338.html
Hibernate的核心组件在基于MVC设计模式的JAVA WEB应用中，Hibernate可以作为模型层/数据访问层。它通过配置文件(hibernate.properties或hibernate.cfg.xml)和映射文件(***.hbm.xml)把JAVA对象或PO(Persistent Object,持久化对象)映射到数据库中的数据库，然后通过操作PO，对数据表中的数据进行增，删，改，查等操作。除配置文件，映射文件和持久化类外，Hibernate的核心组件包括以下几部分：a)Configuration类：用来读取Hibernate配置文件，并生成SessionFactory对象。b)SessionFactory接口：产生Session实例工厂。c)Session接口：用来操作PO。它有get(),load(),save(),update()和delete()等方法用来对PO进行加载，保存，更新及删除等操作。它是Hibernate的核心接口。d)Query接口：用来对PO进行查询操。它可以从Session的createQuery()方法生成。e)Transaction接口：用来管理Hibernate事务，它主要方法有commit()和rollback()，可以从Session的beginTrancation()方法生成。
Persistent Object持久化对象可以是普通的Javabeans,惟一特殊的是它们与（仅一个）Session相关联。JavaBeans在Hibernate中存在三种状态：1.临时状态(transient):当一个JavaBean对象在内存中孤立存在，不与数据库中的数据有任何关联关系时，那么这个JavaBeans对象就称为临时对象(Transient Object)。2.持久化状态(persistent):当一个JavaBean对象与一个Session相关联时，就变成持久化对象(Persistent Object)3.脱管状态(detached):在这个Session被关闭的同时，这个对象也会脱离持久化状态，就变成脱管状态(Detached Object)，可以被应用程序的任何层自由使用，例如可以做与表示层打交道的数据舆对象(Data Transfer Object)。
Hibernate的运行过程Hibernate的运行过程如下：A:应用程序先调用Configration类，该类读取Hibernate的配置文件及映射文件中的信息，并用这些信息生成一个SessionFactpry对象。B:然后从SessionFactory对象生成一个Session对象，并用Session对象生成Transaction对象;可通过Session对象的get(),load(),save(),update(),delete()和saveOrUpdate()等方法对PO进行加载，保存，更新，删除等操作;在查询的情况下，可通过Session对象生成一个Query对象，然后利用Query对象执行查询操作;如果没有异常，Transaction对象将 提交这些操作结果到数据库中。Hibernate的运行过程如下图：
Hibernate简单示例：
数据： table T_register
( id int primary key, userName varchar(30), userPwd varchar(30), sex varchar(10), age int)
视图层：注册页面register.jsp ( id int primary key, userName varchar(30), userPwd varchar(30), sex varchar(10), age int) <% =java contentType""=GBK%><!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=GBK"><title>Insert title here</title></head><body><form action="servlet/RegisterServlet" method="POST"> 用户名：<input type="text" name="userName" /><BR> 密 码：<input type="text" name="userPwd" /><BR> 性 别：<input type="text" name="sex" /><BR> 年 龄：<input type="text" name="age" /><BR> <input type="submit" value="save" /></form></body></html>
设计持久化类TRegister.java <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html><head><meta http-equiv="Content-Type" content="text/html; charset=GBK"><title>Insert title here</title></head><body><form action="servlet/RegisterServlet" method="POST"> 用户名：<input type="text" name="userName" /><BR> 密 码：<input type="text" name="userPwd" /><BR> 性 别：<input type="text" name="sex" /><BR> 年 龄：<input type="text" name="age" /><BR> <input type="submit" value="save" /></form></body></html> /**
* 持久化类
*/
public class TRegister implements java.io.Serializable { // Fields private Integer id; private String userName; private String userPwd; private String sex; private Integer age; // Constructors
/** default constructor */ public TRegister() { 
} /** minimal constructor */ public TRegister(Integer id) { this.id = id; } /** full constructor */ public TRegister(Integer id, String userName, String userPwd, String sex, Integer age) { this.id = id; this.userName = userName; this.userPwd = userPwd; this.sex = sex; this.age = age; } // Property accessors public Integer getId() { return this.id; } public void setId(Integer id) { this.id = id; } public String getUserName() { return this.userName; } public void setUserName(String userName) { this.userName = userName; } public String getUserPwd() { return this.userPwd; } public void setUserPwd(String userPwd) { this.userPwd = userPwd; } public String getSex() { return this.sex; } public void setSex(String sex) { this.sex = sex; } public Integer getAge() { return this.age; } public void setAge(Integer age) { this.age = age; }}
设计Hibernate配置文件hibernate.cfg.xml * 持久化类 */public class TRegister implements java.io.Serializable { // Fields private Integer id; private String userName; private String userPwd; private String sex; private Integer age; // Constructors /** default constructor */ public TRegister() { } /** minimal constructor */ public TRegister(Integer id) { this.id = id; } /** full constructor */ public TRegister(Integer id, String userName, String userPwd, String sex, Integer age) { this.id = id; this.userName = userName; this.userPwd = userPwd; this.sex = sex; this.age = age; } // Property accessors public Integer getId() { return this.id; } public void setId(Integer id) { this.id = id; } public String getUserName() { return this.userName; } public void setUserName(String userName) { this.userName = userName; } public String getUserPwd() { return this.userPwd; } public void setUserPwd(String userPwd) { this.userPwd = userPwd; } public String getSex() { return this.sex; } public void setSex(String sex) { this.sex = sex; } public Integer getAge() { return this.age; } public void setAge(Integer age) { this.age = age; }} xml version='1.0' encoding='UTF-8' ?><!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><!-- Generated by MyEclipse Hibernate Tools. --><hibernate-configuration><session-factory> <property name="connection.username">root</property> <property name="connection.url"> jdbc:mysql://localhost:3306/study </property> <property name="dialect"> org.hibernate.dialect.MySQLDialect </property> <property name="myeclipse.connection.profile">MySQL5.0</property> <property name="connection.password">root</property> <property name="connection.driver_class"> org.gjt.mm.mysql.Driver </property> <property name="show_sql">true</property> <mapping resource="hibernate/PO/TRegister.hbm.xml" /></session-factory></hibernate-configuration>
设计映射文件TRegister.hbm.xml <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><!-- Generated by MyEclipse Hibernate Tools. --><hibernate-configuration><session-factory> <property name="connection.username">root</property> <property name="connection.url"> jdbc:mysql://localhost:3306/study </property> <property name="dialect"> org.hibernate.dialect.MySQLDialect </property> <property name="myeclipse.connection.profile">MySQL5.0</property> <property name="connection.password">root</property> <property name="connection.driver_class"> org.gjt.mm.mysql.Driver </property> <property name="show_sql">true</property> <mapping resource="hibernate/PO/TRegister.hbm.xml" /></session-factory></hibernate-configuration> xml version="1.0" encoding="utf-8" ?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><!-- Mapping file autogenerated by MyEclipse - Hibernate Tools--><hibernate-mapping> <class name="hibernate.PO.TRegister" table="t_register"> <id name="id" type="java.lang.Integer"> <column name="id" /> <!-- 我在MYSQL中并没有设置该字段递增，但在Hibernate中依然可以设置为递增 --> <generator class="increment" /> </id> <property name="userName" type="java.lang.String"> <column name="userName" length="30" /> </property> <property name="userPwd" type="java.lang.String"> <column name="userPwd" length="30" /> </property> <property name="sex" type="java.lang.String"> <column name="sex" length="10" /> </property> <property name="age" type="java.lang.Integer"> <column name="age" /> </property> </class></hibernate-mapping>
设计hibernate基础类HibernateUtil.java <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><!-- Mapping file autogenerated by MyEclipse - Hibernate Tools--><hibernate-mapping> <class name="hibernate.PO.TRegister" table="t_register"> <id name="id" type="java.lang.Integer"> <column name="id" /> <!-- 我在MYSQL中并没有设置该字段递增，但在Hibernate中依然可以设置为递增 --> <generator class="increment" /> </id> <property name="userName" type="java.lang.String"> <column name="userName" length="30" /> </property> <property name="userPwd" type="java.lang.String"> <column name="userPwd" length="30" /> </property> <property name="sex" type="java.lang.String"> <column name="sex" length="10" /> </property> <property name="age" type="java.lang.Integer"> <column name="age" /> </property> </class></hibernate-mapping> /** * hibernate 基础类 * @author fengyan * date 2007-01-09 02:32 */import org.hibernate.HibernateException;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;public class HibernateUtil { private static final SessionFactory sessionFactory; static { try { Configuration config = new Configuration().configure("/hibernate/hibernate.cfg.xml"); sessionFactory = config.buildSessionFactory(); } catch(Throwable e) { throw new ExceptionInInitializerError(e); } } public static final ThreadLocal session = new ThreadLocal(); public static Session currentSession() throws HibernateException { Session s = (Session)session.get(); //Open a new Session,if this Thread has none yet if(s == null || !s.isOpen()) { s = sessionFactory.openSession(); session.set(s); } return s; } public static void closeSession() throws HibernateException { Session s = (Session)session.get(); session.set(null); if(s != null) s.close(); }}
设计控制类 * hibernate 基础类 * @author fengyan * date 2007-01-09 02:32 */import org.hibernate.HibernateException;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.Configuration;public class HibernateUtil { private static final SessionFactory sessionFactory; static { try { Configuration config = new Configuration().configure("/hibernate/hibernate.cfg.xml"); sessionFactory = config.buildSessionFactory(); } catch(Throwable e) { throw new ExceptionInInitializerError(e); } } public static final ThreadLocal session = new ThreadLocal(); public static Session currentSession() throws HibernateException { Session s = (Session)session.get(); //Open a new Session,if this Thread has none yet if(s == null || !s.isOpen()) { s = sessionFactory.openSession(); session.set(s); } return s; } public static void closeSession() throws HibernateException { Session s = (Session)session.get(); session.set(null); if(s != null) s.close(); }} /** * @author fengyan * date 2007-01-09 02:44 * 设计Hibernate控制类 */import hibernate.HibernateUtil;import hibernate.PO.TRegister;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.hibernate.HibernateException;import org.hibernate.Session;import org.hibernate.Transaction;public class RegisterServlet extends HttpServlet { private static final String CONTENT_TYPE = "text/html;charset=GBK"; public void init() throws ServletException { // Put your code here } public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType(CONTENT_TYPE); request.setCharacterEncoding("GBK"); PrintWriter out = response.getWriter(); String userName = request.getParameter("userName"); String userPwd = request.getParameter("userPwd"); String sex = request.getParameter("sex"); int age = Integer.parseInt(request.getParameter("age")); TRegister rg = new TRegister(); rg.setAge(age); rg.setSex(sex); rg.setUserName(userName); rg.setUserPwd(userPwd); Session session = HibernateUtil.currentSession();//生成Session实例 Transaction tx = session.beginTransaction(); try { session.save(rg); //保存持久类对象 tx.commit(); //提交到数据库 session.close(); response.sendRedirect("registerOK.jsp"); } catch(HibernateException e) { e.printStackTrace(); tx.rollback(); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request,response); }}
编译----->打包----->运行----->OK！ * @author fengyan * date 2007-01-09 02:44 * 设计Hibernate控制类 */import hibernate.HibernateUtil;import hibernate.PO.TRegister;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.hibernate.HibernateException;import org.hibernate.Session;import org.hibernate.Transaction;public class RegisterServlet extends HttpServlet { private static final String CONTENT_TYPE = "text/html;charset=GBK"; public void init() throws ServletException { // Put your code here } public void destroy() { super.destroy(); // Just puts "destroy" string in log // Put your code here } public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType(CONTENT_TYPE); request.setCharacterEncoding("GBK"); PrintWriter out = response.getWriter(); String userName = request.getParameter("userName"); String userPwd = request.getParameter("userPwd"); String sex = request.getParameter("sex"); int age = Integer.parseInt(request.getParameter("age")); TRegister rg = new TRegister(); rg.setAge(age); rg.setSex(sex); rg.setUserName(userName); rg.setUserPwd(userPwd); Session session = HibernateUtil.currentSession();//生成Session实例 Transaction tx = session.beginTransaction(); try { session.save(rg); //保存持久类对象 tx.commit(); //提交到数据库 session.close(); response.sendRedirect("registerOK.jsp"); } catch(HibernateException e) { e.printStackTrace(); tx.rollback(); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request,response); }}