java中hibernate二级缓存详解

true

 
    org.hibernate.cache.EhCacheProvider

package com.sihai.hibernate3.test; 
 
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.sihai.hibernate3.demo1.Customer; 
import com.sihai.hibernate3.demo1.Order; 
import com.sihai.utils.HibernateUtils; 
 
public class HibernateTest6 { 
  
 @Test 
 // 查询缓存的测试 
 public void demo9(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  Query query = session.createQuery("select c.cname from Customer c"); 
  // 使用查询缓存: 
  query.setCacheable(true); 
  query.list(); 
   
  tx.commit(); 
   
  session = HibernateUtils.getCurrentSession(); 
  tx = session.beginTransaction(); 
   
  query = session.createQuery("select c.cname from Customer c"); 
  query.setCacheable(true); 
  query.list(); 
   
  tx.commit(); 
 } 
  
 @SuppressWarnings("unused") 
 @Test 
 // 更新时间戳 
 public void demo8(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  Customer customer = (Customer) session.get(Customer.class, 2); 
  session.createQuery("update Customer set cname = '奶茶' where cid = 2").executeUpdate(); 
   
  tx.commit(); 
   
  session = HibernateUtils.getCurrentSession(); 
  tx = session.beginTransaction(); 
   
  Customer customer2 = (Customer) session.get(Customer.class, 2); 
   
  tx.commit(); 
 } 
  
 @SuppressWarnings("all") 
 @Test 
 // 将内存中的数据写到硬盘 
 public void demo7(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  List list = session.createQuery("from Order").list(); 
   
  tx.commit(); 
 } 
  
 @Test 
 // 一级缓存的更新会同步到二级缓存: 
 public void demo6(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  Customer customer = (Customer) session.get(Customer.class, 1); 
  customer.setCname("芙蓉"); 
   
  tx.commit(); 
   
  session = HibernateUtils.getCurrentSession(); 
  tx = session.beginTransaction(); 
   
  Customer customer2 = (Customer) session.get(Customer.class, 1); 
   
  tx.commit(); 
 } 
  
 @SuppressWarnings("unchecked") 
 @Test 
 // iterate()方法可以查询所有信息. 
 // iterate方法会发送N+1条SQL查询.但是会使用二级缓存的数据 
 public void demo5(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  // N+1条SQL去查询. 
  Iterator iterator = session.createQuery("from Customer").iterate(); 
  while(iterator.hasNext()){ 
   Customer customer = iterator.next(); 
   System.out.println(customer); 
  } 
   
  tx.commit(); 
   
  session = HibernateUtils.getCurrentSession(); 
  tx = session.beginTransaction(); 
   
  iterator = session.createQuery("from Customer").iterate(); 
  while(iterator.hasNext()){ 
   Customer customer = iterator.next(); 
   System.out.println(customer); 
  } 
   
  tx.commit(); 
 } 
  
 @SuppressWarnings("unchecked") 
 @Test 
 // 查询所有.Query接口的list()方法. 
 // list()方法会向二级缓存中放数据,但是不会使用二级缓存中的数据. 
 public void demo4(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  // 查询所有客户: 
  // list方法会向二级缓存中放入数据的. 
  List list = session.createQuery("from Customer").list(); 
  for (Customer customer : list) { 
   System.out.println(customer.getCname()); 
  } 
  tx.commit(); 
   
  session = HibernateUtils.getCurrentSession(); 
  tx = session.beginTransaction(); 
   
  // Customer customer = (Customer) session.get(Customer.class, 1);// 没有发生SQL ,从二级缓存获取的数据. 
  // list()方法没有使用二级缓存的数据. 
  list = session.createQuery("from Customer").list(); 
  for (Customer customer : list) { 
   System.out.println(customer.getCname()); 
  } 
   
  tx.commit(); 
 } 
  
 @Test 
 // 二级缓存的集合缓冲区特点: 
 public void demo3(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  Customer customer = (Customer) session.get(Customer.class, 1); 
  // 查询客户的订单. 
  System.out.println("订单的数量:"+customer.getOrders().size()); 
   
  tx.commit(); 
   
  session = HibernateUtils.getCurrentSession(); 
  tx = session.beginTransaction(); 
   
  Customer customer2 = (Customer) session.get(Customer.class, 1); 
  // 查询客户的订单. 
  System.out.println("订单的数量:"+customer2.getOrders().size()); 
   
  tx.commit(); 
 } 
  
 @SuppressWarnings("unused") 
 @Test 
 // 配置二级缓存的情况 
 public void demo2(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  Customer customer1 = (Customer) session.get(Customer.class, 1);// 发送SQL. 
   
  Customer customer2 = (Customer) session.get(Customer.class, 1);// 不发送SQL. 
   
  System.out.println(customer1 == customer2); 
   
  tx.commit(); 
   
  session = HibernateUtils.getCurrentSession(); 
  tx = session.beginTransaction(); 
   
  Customer customer3 = (Customer) session.get(Customer.class, 1);// 不发送SQL. 
  Customer customer4 = (Customer) session.get(Customer.class, 1);// 不发送SQL. 
   
  System.out.println(customer3 == customer4); 
   
  tx.commit(); 
 } 
  
  
 @SuppressWarnings("unused") 
 @Test 
 // 没有配置二级缓存的情况 
 public void demo1(){ 
  Session session = HibernateUtils.getCurrentSession(); 
  Transaction tx = session.beginTransaction(); 
   
  Customer customer1 = (Customer) session.get(Customer.class, 1);// 发送SQL. 
   
  Customer customer2 = (Customer) session.get(Customer.class, 1);// 不发送SQL. 
   
   
   
  tx.commit(); 
   
  session = HibernateUtils.getCurrentSession(); 
  tx = session.beginTransaction(); 
   
  Customer customer3 = (Customer) session.get(Customer.class, 1);// 发送SQL. 
   
   
  tx.commit(); 
 } 
}