Hibernate框架小demo

1.核心配置文件

hibernate.cfg.xml

<?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">
<hibernate-configuration>
    <session-factory>
    	<!-- 配置JDBC驱动 -->
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <!-- 配置数据库用户名 -->
        <property name="hibernate.connection.username">root</property>
        <!-- 配置数据库密码 -->
        <property name="hibernate.connection.password">123456</property>
        <!-- 连接数据库URL -->
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mysqldb</property>
        <!-- 配置数据库方言 -->
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <!-- 配置JDBC内置连接池 -->
        <property name="connection.pool_size">1</property>
        <!--   配置数据库方言 -->
        <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
        <!--  输出运行时生成的SQL语句-->
        <property name="show_sql">true</property>
        
        
        <!-- 列出所有的映射文件 -->
        <mapping resource="org/hibernate/entity/User.hbm.xml"/>
        
    </session-factory>
</hibernate-configuration>

2.目录

org.hibernate.entity

        1.实体类

        注意：必须有一个标识键  2.必须有一个默认的构造方法  

User.java

package org.hibernate.entity;

public class User {
	private int id;//2.必须有一个标识属性，主键
	private String name;
	private String password;
	private String type;
	
	//1,必须有默认的构造方法，这样hibernate就可以运用Java的反射机制啦
	 public User() {
		
	}
	
	public int getId() {
		return id;
	}
	
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public String getType() {
		return type;
	}
	public void setType(String type) {
		this.type = type;
	}
	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", password=" + password
				+ ", type=" + type + "]";
	}
	

}

2.User.hbm.xml

<?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">
<hibernate-mapping>
    <class name="org.hibernate.entity.User" table="USER">
        <id name="id" type="java.lang.Integer" column="USER_ID">
            <generator class="increment" />
        </id>
        <property name="name" type="java.lang.String">
       	<column name="NAME" length="20"></column>
        </property>
        <property name="password" type="java.lang.String" >
        <column name="PASSWORD" length="12"></column>
        </property>
        <property name="type" type="java.lang.String" >
        <column name="TYPE" length="6"></column>
        </property>
    </class>
</hibernate-mapping>

3.辅助工具类

package org.hibernate.entity;

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

//辅助工具库勒
public class HibernateUntil {
	private static SessionFactory sessionFactory;
	private static Configuration configuration = new Configuration();
	// 创建线程局部变量threadLocal。用来保存Hibernate的session
	private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
	// 使用静态代码块初始化Hbernate
	static {
		try {
			// 读取配置文件hibernate.cfg.xml
			//new Configuration()方法被调用时Hibernate再ClassPath目录小查找hibernate.properies文件
			//configure（)方法呗调用时会再classpath的根目路下查找hibernate.cfg.xml文件
			
			Configuration cfg = new Configuration().configure();
			// 创建SessionFactory
			sessionFactory = cfg.buildSessionFactory();

		} catch (Throwable e) {
			throw new ExceptionInInitializerError(e);
		}
	}

	// 获取Sessionfactory实例
	public static SessionFactory getSessionFactory() {
		return sessionFactory;
	}

	// 获取ThreadLocal对象管理的Session实例
	public static Session getSession() throws HibernateException {
		Session session = (Session) threadLocal.get();
		if (session == null || !session.isOpen()) {
			if (sessionFactory == null) {
				rebuildSessionFactory();
			}
			// 通过sessionfactoory对象创建session对象
			session = (sessionFactory != null) ? sessionFactory.openSession()
					: null;
			// 将新打开的实例保存到线程局部变量threadLocal中
			threadLocal.set(session);
		}
		return session;
	}

	// 关闭session实例
	public static void closeSession() throws HibernateException {
		// 从县城局部变量threadLocal中获取之前存入的Session实例
		Session session = (Session) threadLocal.get();
		threadLocal.set(null);
		if (session != null) {
			session.close();
		}
	}

	// 重建SessionFactory
	public static void rebuildSessionFactory() {
		try {
			// 读取配置文件hibernate.cfg.xml
			configuration.configure("/hibernate.cfg.xml");
			// 创建SessionFactory
			sessionFactory = configuration.buildSessionFactory();
		} catch (Exception e) {
			// TODO: handle exception
		}
	}

	// 关闭缓存连接池子
	public static void shutdown() {
		getSessionFactory().close();
	}

}

3.org.hibernate.dao

        1.UserDao.java

package org.hibernate.dao;

import java.util.List;
import org.hibernate.entity.User;
//创建UserDAO接口
public interface UserDao {
	 void save(User user);				//添加用户
	 User findById(int id);				//根据用户标识查找指定用户	 
void delete(User user);				//删除用户	
	 void update(User user);				//修改用户信息
}

        2.UserDaoImpl.java

package org.hibernate.dao;

import org.hibernate.*;
import org.hibernate.entity.*;

public class UserDaoImpl implements UserDao {
	// 添加用户
	public void save(User user) {
		Session session = HibernateUntil.getSession(); // 生成Session实例
		Transaction tx = session.beginTransaction(); // 创建Transaction实例
		try {
			session.save(user); // 使用Session的save方法将持久化对象保存到数据库
			tx.commit(); // 提交事务
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback(); // 回滚事务
		} finally {
			HibernateUntil.closeSession(); // 关闭Session实例
		}
	}

	// 根据用户标识查找指定用户
	public User findById(int id) {
		User user = null;
		Session session = HibernateUntil.getSession(); // 生成Session实例
		Transaction tx = session.beginTransaction(); // 创建Transaction实例
		try {
			user = (User) session.get(User.class, id); // 使用Session的get方法获取指定id的用户到内存中
			tx.commit(); // 提交事务
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback(); // 回滚事务
		} finally {
			HibernateUntil.closeSession(); // 关闭Session实例
		}
		return user;
	}

	// 删除用户
	public void delete(User user) {
		Session session = HibernateUntil.getSession(); // 生成Session实例
		Transaction tx = session.beginTransaction(); // 创建Transaction实例
		try {
			session.delete(user); // 使用Session的delete方法将持久化对象删除
			tx.commit(); // 提交事务
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback(); // 回滚事务
		} finally {
			HibernateUntil.closeSession(); // 关闭Session实例
		}
	}

	// 修改用户信息
	public void update(User user) {
		Session session = HibernateUntil.getSession(); // 生成Session实例
		Transaction tx = session.beginTransaction(); // 创建Transaction实例
		try {
			session.update(user); // 使用Session的update方法更新持久化对象
			tx.commit(); // 提交事务
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback(); // 回滚事务
		} finally {
			HibernateUntil.closeSession(); // 关闭Session实例
		}
	}
}

                3.DAOFactory.java

    

package org.hibernate.dao;

public class DAOFactory {
	//返回USERDAO实现类的实例
	//避免出现多种数据库时，多余的灭必要的修改
	public static UserDao getUserDaoInstance()
	{
		return new UserDaoImpl();
	}
}