Hibernate框架之一级缓存

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一级缓存:

一级缓存不能跨session, 只能缓存实体对象, 不能缓存属性

package com.rl.hiber.test;

import java.util.Date;
import java.util.Iterator;
import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;

import com.rl.hiber.model.User;
import com.rl.hiber.utils.HibernateUtils;

/**
 * 不跨session的一级缓存
 * @author Administrator
 *
 */
public class TestHibernate {
	
	@Test
	public void testAdd(){
		Session session = HibernateUtils.getSession();
		Transaction tx = session.beginTransaction();
		
		try {
			for(int i = 0; i < 10; i++){
			    User user = new User();
			    user.setUname("张三");
	            user.setGender(1);
	            user.setBirthday(new Date());
	            session.save(user);
			}
			tx.commit();
		} catch (Exception e) {
			e.printStackTrace();
			tx.rollback();
		}finally{
			HibernateUtils.closeResource(session);
		}
	}
	
	/**
	 * load方法使用一级缓存
	 */
	@Test
	public void query1(){
	    Session session = HibernateUtils.getSession();
	    try {
	        //发出sql
            User user = (User)session.load(User.class, 1);
            System.out.println(user);
            //不发sql(一级缓存)
            User user1 = (User)session.load(User.class, 1);
            System.out.println(user1);
        } finally{
            HibernateUtils.closeResource(session);
        }
	}
	
	/**
	 * get的方法使用一级缓存
	 */
	@Test
	public void query2(){
	    Session session = HibernateUtils.getSession();
	    try {
	        User user = (User)session.get(User.class, 1);
	        System.out.println(user);
	        User user1 = (User)session.load(User.class, 1);
	        System.out.println(user1);
	    } finally{
	        HibernateUtils.closeResource(session);
	    }
	}
	
	/**
	 * list方法查询不使用一级缓存
	 */
	@Test
	public void query3(){
	    Session session = HibernateUtils.getSession();
	    try {
            Query query = session.createQuery("from User");
            //发出sql
            List<User> userList = query.list();
            for(User user: userList){
                System.out.println(user);
            }
            
            Query query1 = session.createQuery("from User");
            //发出sql
            List<User> userList1 = query1.list();
            for(User user: userList1){
                System.out.println(user);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
	}
	
	/**
	 * iterate方法查询使用一级缓存
	 */
	@Test
	public void query4(){
	    Session session = HibernateUtils.getSession();
	    try {
	        Query query = session.createQuery("from User");
	        //发出sql 查出所有id
	        Iterator<User> iterator = query.iterate();
	        while(iterator.hasNext()){
	            //根据具体的每一个id查出详情
	            User user = iterator.next();
	            System.out.println(user);
	        }
	        
	        Query query1 = session.createQuery("from User");
	        //发出sql 查出所有的id
	        Iterator<User> iterator1 = query1.iterate();
	        while(iterator1.hasNext()){
	            //不在发出sql, 使用一级缓存
	            User user = iterator1.next();
	            System.out.println(user);
	        }
	    } catch (Exception e) {
	        e.printStackTrace();
	    }
	}
}

package com.rl.hiber.test;

import java.util.Date;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;

import com.rl.hiber.model.User;
import com.rl.hiber.utils.HibernateUtils;

public class TestHibernate2 {
	
    /**
     * 无法跨session
     */
	@Test
	public void query1(){
	    Session session = HibernateUtils.getSession();
	    try {
	        //发出sql
            User user = (User)session.load(User.class, 1);
            System.out.println(user);
        } finally{
            //关闭session
            HibernateUtils.closeSession(session);
        }
	    
	    Session session1 = HibernateUtils.getSession();
	    try {
	        //发出sql
	        User user = (User)session1.load(User.class, 1);
	        System.out.println(user);
	    } finally{
	        HibernateUtils.closeResource(session1);
	    }
	}
	
	/**
	 * 一级缓存不能缓存属性
	 */
	@Test
	public void query2(){
	    Session session = HibernateUtils.getSession();
	    
	    try {
	        Query query = session.createQuery("select u.uname from User u where u.userId = 1");
	        //发出sql
	        Object name = query.uniqueResult();
	        System.out.println(name);
	        
	        Query query1 = session.createQuery("select u.uname from User u where u.userId = 1");
	        //发出sql
	        Object name1 = query1.uniqueResult();
	        System.out.println(name1);
	    } finally{
	        HibernateUtils.closeResource(session);
	    }
	}
	
	/**
	 * 一级缓存的刷新
	 */
	@Test
    public void update(){
        Session session = HibernateUtils.getSession();
        Transaction tx = session.beginTransaction();
        try {
            //发出sql
            User user = (User)session.load(User.class, 1);
            System.out.println(user);
            //发出update的sql, 同时更新一级缓存
            user.setUname("李四");
            session.update(user);
            tx.commit();
            //不发出sql, 查询到的是更新后的数据
            User use1 = (User)session.load(User.class, 1);
            System.out.println(use1);
        } catch(Exception e){
            e.printStackTrace();
            tx.rollback();
        }finally{
            HibernateUtils.closeResource(session);
        }
    }
	
	/**
	 * 保存时刷新缓存
	 */
	@Test
	public void save(){
	    Session session = HibernateUtils.getSession();
	    Transaction tx = session.beginTransaction();
	    try {
	        User user = new User();
	        user.setBirthday(new Date());
	        user.setGender(1);
	        user.setUname("赵六");
	        //发出insert的sql
	        session.save(user);
	        
	        //不发出sql, 直接从一级缓存中获取数据
	        User user1 = (User)session.load(User.class, user.getUserId());
	        System.out.println(user1);
	        
	        tx.commit();
	    } catch(Exception e){
	        e.printStackTrace();
	        tx.rollback();
	    }finally{
	        HibernateUtils.closeResource(session);
	    }
	}
	
	/**
	 * 一级缓存的管理(evit()和clear())
	 */
	@Test
	public void manageTest(){
	    Session session = HibernateUtils.getSession();
	    try {
	        //发出sql
            User user = (User)session.load(User.class, 2);
            System.out.println(user);

            //将一级缓存中的user逐出
            session.evict(user);
            //把一级缓存中所有的数据都清空
            session.clear();
            
            //必须重新发出sql
            User user1 = (User)session.load(User.class, 2);
            System.out.println(user1);
        } finally{
            HibernateUtils.closeResource(session);
        }
	}
}