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();
}
}
