list方法会一次查出所有内容，放在list里和缓存中。再次查询同一内容仍然会去数据库重新查一遍，并刷新缓存。

iterate方法会一次查出所有内容的ID，等用到某个ID对应的内容时又会去根据主键查询内容，并放在缓存中，当再次查询相同的内容时不再查询数据库，直接调用session级缓存。

 

import java.util.Date;

import java.util.Iterator;

import java.util.List;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.AnnotationConfiguration;

import org.hibernate.tool.hbm2ddl.SchemaExport;

import org.junit.AfterClass;

import org.junit.BeforeClass;

import org.junit.Test;

public class HibernateQLTest {

    private static SessionFactory sf;

   

    @BeforeClass

    public static void beforeClass() {

        sf = new AnnotationConfiguration().configure().buildSessionFactory();

    }

    @AfterClass

    public static void afterClass() {

        sf.close();

    }

   

    @Test

    public void testSchemaExport() {

        new SchemaExport(new AnnotationConfiguration().configure()).create(false, true);

    }

   

    @Test

    public void testSave() {

        Session session = sf.openSession();

        session.beginTransaction();

       

        for(int i=0; i<10; i++) {

            Category c = new Category();

            c.setName("c" + i);

            Topic t = new Topic();

            t.setCategory(c);

            t.setTitle("t" + i);

            t.setCreateDate(new Date());

            session.save(c);

            session.save(t);

        }

           

        session.getTransaction().commit();

        session.close();

    }

   

    //join fetch

    @Test

    public void testQueryList() {

        Session session = sf.openSession();

        session.beginTransaction();

        //List<Topic> topics = (List<Topic>)session.createCriteria(Topic.class).list();

        List<Category> categories = (List<Category>)session.createQuery("from Category").list();

       

        for(Category c : categories) {

            System.out.println(c.getName());

        }

       

        List<Category> categories2 = (List<Category>)session.createQuery("from Category").list();

        for(Category c : categories2) {

            System.out.println(c.getName());

        }

        session.getTransaction().commit();

        session.close();

       

    }

   

    @Test

    public void testQueryIterate() {

        Session session = sf.openSession();

        session.beginTransaction();

        //List<Topic> topics = (List<Topic>)session.createCriteria(Topic.class).list();

        Iterator<Category> categories = (Iterator<Category>)session.createQuery("from Category").iterate();

       

       

        while(categories.hasNext()) {

            Category c = categories.next();

            System.out.println(c.getName());

        }

       

        Iterator<Category> categories2 = (Iterator<Category>)session.createQuery("from Category").iterate();

       

        while(categories2.hasNext()) {

            Category c = categories2.next();

            System.out.println(c.getName());

        }

        session.getTransaction().commit();

        session.close();

       

    }

    public static void main(String[] args) {

        beforeClass();

    }

}