hibernate iterate list 区别

iterate:

	        String sql = "from Bigque where id <= 5";
		String sql2 = "from Bigque where id <= 6";
		BigqueDAO dao = new BigqueDAO();
		Session session = dao.getSession();
		Iterator<Bigque> it = session.createQuery(sql).iterate();
		
		while(it.hasNext()){
			System.out.println(it.next().getContent());
		}
		
		System.out.println("===========");
		
                Iterator<Bigque> it2 = session.createQuery(sql2).iterate();
		
		while(it2.hasNext()){
			System.out.println(it2.next().getContent());
		}
		session.close();

结果：

Hibernate: select bigque0_.ID as col_0_0_ from cloudroom.bigque bigque0_ where bigque0_.ID<=5
Hibernate: select bigque0_.ID as ID51_0_, bigque0_.Content as Content51_0_, bigque0_.SubjectID as SubjectID51_0_ from cloudroom.bigque bigque0_ where bigque0_.ID=?
选择题
Hibernate: select bigque0_.ID as ID51_0_, bigque0_.Content as Content51_0_, bigque0_.SubjectID as SubjectID51_0_ from cloudroom.bigque bigque0_ where bigque0_.ID=?
填空题
Hibernate: select bigque0_.ID as ID51_0_, bigque0_.Content as Content51_0_, bigque0_.SubjectID as SubjectID51_0_ from cloudroom.bigque bigque0_ where bigque0_.ID=?
阅读题
Hibernate: select bigque0_.ID as ID51_0_, bigque0_.Content as Content51_0_, bigque0_.SubjectID as SubjectID51_0_ from cloudroom.bigque bigque0_ where bigque0_.ID=?
判断题
Hibernate: select bigque0_.ID as ID51_0_, bigque0_.Content as Content51_0_, bigque0_.SubjectID as SubjectID51_0_ from cloudroom.bigque bigque0_ where bigque0_.ID=?
选择题
===========
Hibernate: select bigque0_.ID as col_0_0_ from cloudroom.bigque bigque0_ where bigque0_.ID<=6
选择题
填空题
阅读题
判断题
选择题
Hibernate: select bigque0_.ID as ID51_0_, bigque0_.Content as Content51_0_, bigque0_.SubjectID as SubjectID51_0_ from cloudroom.bigque bigque0_ where bigque0_.ID=?
填空题

结论：

延迟加载 先发送一条sql语句获取所有的id  用到的时候再发送SQL去数据库查找每个对象

在一个session中两次iterate   第二个iterate还是会发送一条SQL获取id    用到的时候再发送SQL去数据库查找每个对象（如果session中有这个对象，就在缓存中查找，不发送SQL）

 

list:

                String sql = "from Bigque where id <= 5";
	//	String sql2 = "from Bigque where id <= 6";
		BigqueDAO dao = new BigqueDAO();
		Session session = dao.getSession();
		List<Bigque> list = session.createQuery(sql).list();
		for(int i=0; i<list.size(); i++){
			System.out.println(list.get(i).getContent());
		}
		System.out.println("=============");
		
		List<Bigque> list2 = session.createQuery(sql).list();
		for(int i=0; i<list2.size(); i++){
			System.out.println(list2.get(i).getContent());
		}
		session.close();

结果：

Hibernate: select bigque0_.ID as ID51_, bigque0_.Content as Content51_, bigque0_.SubjectID as SubjectID51_ from cloudroom.bigque bigque0_ where bigque0_.ID<=5
选择题
填空题
阅读题
判断题
选择题
=============
Hibernate: select bigque0_.ID as ID51_, bigque0_.Content as Content51_, bigque0_.SubjectID as SubjectID51_ from cloudroom.bigque bigque0_ where bigque0_.ID<=5
选择题
填空题
阅读题
判断题
选择题

结论：list取所有  第二次发出仍会到数据库查找