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本文探讨了Hibernate框架中不同检索策略的应用，包括延迟加载和立即加载，以及这些策略如何影响应用程序的性能。
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package org.rabbitx.hibernate4.searchstrategy;

import java.util.List;

import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;

/**
 * 
 * @author RabbitX
 */
public class SearchStrategyJUnitTest {

	private static SessionFactory sessionFactory;
	private static Session session;
	private static Transaction transaction;
	
	@BeforeClass
	public static void beforeClass()
	{
		String cfgPath = "org/rabbitx/hibernate4/searchstrategy/hibernate.cfg.xml";
		Configuration cfg = new Configuration().configure(cfgPath);
		ServiceRegistry serviceRegistry = new ServiceRegistryBuilder().applySettings(cfg.getProperties()).buildServiceRegistry();
		sessionFactory = cfg.buildSessionFactory(serviceRegistry);
		session = sessionFactory.openSession();
	}
	
	@AfterClass
	public static void afterClass()
	{
		sessionFactory.close();
	}
	
	@Before
	public void before()
	{
		session = sessionFactory.openSession();
		transaction = session.beginTransaction();
	}
	
	@After
	public void after()
	{
		if(session.isOpen())
		{
			transaction.commit();
			session.close();
		}
	}
	
	/**
	 * 准备需要的数据
	 */
	@Test
	public void testPrepareData()
	{
		Customer customer = new Customer("BluceLi");
		
		Order order1 = new Order(100090001);
		Order order2 = new Order(100090002);
		Order order3 = new Order(100090003);
		Order order4 = new Order(100090004);
		Order order5 = new Order(100090005);
		Order order6 = new Order(100090006);
		Order order7 = new Order(100090007);
		Order order8 = new Order(100090008);
		Order order9 = new Order(100090009);
		
		//设定关联关系
		order1.setCustomer(customer);
		order2.setCustomer(customer);
		order3.setCustomer(customer);
		order4.setCustomer(customer);
		order5.setCustomer(customer);
		order6.setCustomer(customer);
		order7.setCustomer(customer);
		order8.setCustomer(customer);
		order9.setCustomer(customer);
		
		customer.getOrders().add(order1);
		customer.getOrders().add(order2);
		customer.getOrders().add(order3);
		customer.getOrders().add(order4);
		customer.getOrders().add(order5);
		customer.getOrders().add(order6);
		customer.getOrders().add(order7);
		customer.getOrders().add(order8);
		customer.getOrders().add(order9);

		session.save(customer);
		session.save(order1);
		session.save(order2);
		session.save(order3);
		session.save(order4);
		session.save(order5);
		session.save(order6);
		session.save(order7);
		session.save(order8);
		session.save(order9);
	}

	/**
	 * 在Customer.hbm.xml文件中class节点不设置lazy属性时，默认值为true。
	 *    <class name="Customer" table="TBL_SEARCH_STRATEGY_CUSTOMER" lazy="true">
	 *    在此设置下使用load方法检索数据时为延迟检索。
	 * 执行结果：
	 *    不发送SQL;
	 *    返回一个hibernate创建的代理对象(org.rabbitx.hibernate4.searchstrategy.Customer_$$_javassist_0);    
	 */
	@Test
	public void testClassLazy001()
	{
		Customer customer = (Customer) session.load(Customer.class, 1);
		//返回结果:org.rabbitx.hibernate4.searchstrategy.Customer_$$_javassist_0
		System.out.println(customer.getClass().getName());
		System.out.println(customer.getId());
	}
	
	/**
	 * 配置：<class name="Customer" table="TBL_SEARCH_STRATEGY_CUSTOMER">
	 * 延迟检索情况下，在应用程序第一次访问代理类实例的非 OID 属性时, Hibernate 会初始化代理类实例
	 */
	@Test
	public void testClassLazy002()
	{
		Customer customer = (Customer) session.load(Customer.class, 1);
		System.out.println(customer.getName());
		System.out.println(customer.getClass().getName());
	}
	
	/**
	 * 配置：<class name="Customer" table="TBL_SEARCH_STRATEGY_CUSTOMER" lazy="false">
	 * 立即检索情况下，立即检索数据，hibernate不再创建代理对象。
	 * 执行结果：
	 *    发送SQL;
	 *    返回原对象(org.rabbitx.hibernate4.searchstrategy.Customer);    
	 */
	@Test
	public void testClassLazy003()
	{
		Customer customer = (Customer) session.load(Customer.class, 1);
		System.out.println(customer.getId());
		//返回结果:org.rabbitx.hibernate4.searchstrategy.Customer
		System.out.println(customer.getClass().getName());
	}
	
	/**
	 * 配置：<class name="Customer" table="TBL_SEARCH_STRATEGY_CUSTOMER">
	 * 使用get方法检索数据
	 * 执行结果：
	 *    发送SQL;
	 *    返回原对象(org.rabbitx.hibernate4.searchstrategy.Customer);    
	 */
	@Test
	public void testClassLazy004()
	{
		Customer customer = (Customer) session.get(Customer.class, 1);
		System.out.println(customer.getId());
		//返回结果:org.rabbitx.hibernate4.searchstrategy.Customer
		System.out.println(customer.getClass().getName());
	}
	
	/**
	 * 配置：<class name="Customer" table="TBL_SEARCH_STRATEGY_CUSTOMER">
	 * 使用Query 的 list() 方法检索数据
	 * 执行结果：
	 *    发送SQL;
	 *    返回原对象(org.rabbitx.hibernate4.searchstrategy.Customer);    
	 */
	@Test
	@SuppressWarnings("unchecked")
	public void testClassLazy005()
	{
		Query query = session.createQuery("from Customer");
		List<Customer> customers = query.list();
		System.out.println(customers);
	}
	
	/**
	 * 配置：<set name="orders" table="TBL_SEARCH_STRATEGY_ORDER" inverse="true">
	 *     相当于<set name="orders" table="TBL_SEARCH_STRATEGY_ORDER" inverse="true" lazy="true">
	 * 默认采用延迟检索,通过查看控制台的SQL语句确定
	 */
	@Test
	public void testSetLazy001()
	{
		Customer customer = (Customer) session.load(Customer.class, 1);
		System.out.println(customer.getOrders().getClass());
	}
	
	/**
	 * 配置：<set name="orders" table="TBL_SEARCH_STRATEGY_ORDER" inverse="true" lazy="false">
	 * 默认采用立即检索,通过查看控制台的SQL语句确定
	 */
	@Test
	public void testSetLazy002()
	{
		Customer customer = (Customer) session.load(Customer.class, 1);
		System.out.println(customer.getName());
		System.out.println(customer.getOrders().getClass());
	}
	
	/**
	 * 配置：<set name="orders" table="TBL_SEARCH_STRATEGY_ORDER" inverse="true" lazy="false">
	 * 默认采用立即检索,通过查看控制台的SQL语句确定
	 */
	@Test
	public void testSetLazy003()
	{
		Customer customer = (Customer) session.load(Customer.class, 1);
		System.out.println(customer.getName());
		System.out.println(customer.getOrders().getClass());
	}
}