hibernate基础（一）

package org.hibernate.entity;

public class User{
	// Fields
	private int id;
	private String name;
	private String password;
	private String type;
	// Constructors
	/** default constructor */
	public User() {                                                      
	}
	/** full constructor */
	public User(int id, String name, String password, String type) {
		this.id = id;
		this.name = name;
		this.password = password;
		this.type = type;
	}
	// Property accessors
	public int getId() {
		return this.id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getName() {
		return this.name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPassword() {
		return this.password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
	public String getType() {
		return this.type;
	}
	public void setType(String type) {
		this.type = type;
	}
}

package org.hibernate.entity;

import org.hibernate.*;
import org.hibernate.cfg.*;
public class HibernateUtil {
	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Hibernate
    static {
        try {
        Configuration cfg=new Configuration().configure();	//读取配置文件hibernate.cfg.xml
        //创建ServiceRegistry对象
        ServiceRegistry serviceRegistey=new ServiceRegistryBuilder().applySettings(cfg.getProperties()).buildServiceRegistry();
        //创建SessionFactory
        sessionFactory=cfg.buildSessionFactory(serviceRegistey);		
        } catch (Throwable ex) {
        	throw new ExceptionInInitializerError(ex);
        }
    }
//获得SessionFactory实例
public static SessionFactory getSessionFactory() {
	return sessionFactory;
}
//获得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SessionFactory对象创建Session对象
            session = (sessionFactory != null) ? sessionFactory.openSession(): null;
             //将新打开的Session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 {
//从线程局部变量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 {
	configuration.configure("/hibernate.cfg.xml");			//读取配置文件hibernate.cfg.xml
sessionFactory = configuration.buildSessionFactory();		//创建SessionFactory
		} catch (Exception e) {
			System.err.println("Error Creating SessionFactory ");
			e.printStackTrace();
		}
	}
//关闭缓存和连接池
public static void shutdown() {
		getSessionFactory().close();
	}
}

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
}

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= HibernateUtil.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{
             HibernateUtil. 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= HibernateUtil.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{
             HibernateUtil. closeSession();				//关闭Session实例
        }
        return user;
    }
	//删除用户	
    public void delete(User user){
        Session session= HibernateUtil.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{
             HibernateUtil. closeSession();				//关闭Session实例
        }
    }					
    //修改用户信息
    public void update(User user){
        Session session= HibernateUtil.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{
             HibernateUtil. closeSession();				//关闭Session实例
        }
    }					
}

package org.hibernate.test;
import org.hibernate.dao.*;
import org.hibernate.entity.User;
import org.junit.Before;
import org.junit.Test;

public class UserTest {
	@Before
	public void setUp() throws Exception {
	}
	@Test //test注释表明该方法为一个测试方法
	public void testSave() {
		UserDAO userdao=new UserDAOImpl();	
	     try{
		  User u=new User();			//创建User对象
		  //设置User对象中的各个属性值
		  u.setId(20);
		  u.setName("zhangsan");
		  u.setPassword("456");
		  u.setType("admin");
		  userdao.save(u);				//使用userdaoimpl的save方法将User对象存入数据库
	     }catch(Exception e){
	    	 e.printStackTrace();
	     }
	}
}

File file = new File(“simpleit.xml”);
Configuration cfg = new Configuration().configure(file);

Configuration cfg=new Configuration().configure();	//读取配置文件hibernate.cfg.xml
//创建ServiceRegistry对象
ServiceRegistry serviceRegistey=new ServiceRegistryBuilder().applySettings(cfg.getProperties()).buildServiceRegistry();
//创建SessionFactory
sessionFactory=cfg.buildSessionFactory(serviceRegistey);

Query query=session.createQuery("from User");
int currentPage=1;
int pageSize=10;
query.setFirstResult( (currentPage-1)*pageSize);
query.setMaxResults(pageSize);
List Users=query.list();
session.close();

List users=session.createCriteria(User.class).add(Restrictions.eq("name","jack")).list();
/*
在运行时，转化为：
select * from user where name="jack";
*/

List users=session.createCriteria(User.class)
	.add(Restrictions.eq("name","jack"))
	.addOrder(Order.asc("name"))
	.list();

List users=session.createCriteria(User.class)
	.add(Restrictions.eq("name","jack"))
	.createCriteria("role")
	.add(Restrictions.eq("rolename","admin"))
	.list();
/*
select * from user,role where name="jack" and rolename="admin"
*/

List users=session.createCriteria(User.class)
	.setProjection(Projections.projectionList()
		.add(Projections.rowCount())
		.add(Projections.avg("age"))
		.add(Projections.max("age"))
		.ad(Projections.min("age"))
		.add(Projections.groupProperty("sex"))
	).list();
	
/*
select sex,count(*),avg(age),max(age),min(age) from user group by sex
*/