limitinclausedemo.java

hibernate_tutorial经典教程

/*
 * Created on Mar 18, 2005
 *
 * To change the template for this generated file go to
 * Window - Preferences - Java - Code Generation - Code and Comments
 */
package tutorial.dev.tree;

import java.io.Serializable;
import java.sql.Connection;
import java.util.ArrayList;
import java.util.List;

import net.sf.hibernate.HibernateException;
import net.sf.hibernate.Session;
import net.sf.hibernate.SessionFactory;
import net.sf.hibernate.Transaction;
import net.sf.hibernate.cfg.Configuration;
import net.sf.hibernate.expression.Expression;

/**
 * @author pascal
 *
 * To change the template for this generated type comment go to
 * Window - Preferences - Java - Code Generation - Code and Comments
 */
public class LimitInClauseDemo {
	public static void main(String[] args) {
		try {
			new LimitInClauseDemo();
		} catch(HibernateException he) {
			he.printStackTrace();
		}

	}
	public LimitInClauseDemo() throws HibernateException {
	Configuration config = new Configuration();
	// add the classes you want to persist
	// make sure the mapping files are on the classpath
	config.addClass(Friend.class);
	
	SessionFactory sf = config.buildSessionFactory();

	Session sess = sf.openSession();
	Transaction tx = null;
	
	List ids = new ArrayList();
	
	/*
	try {
		tx = sess.beginTransaction();
		long start = System.currentTimeMillis(); 
		for (int i = 0; i < 200000; i++) {
			
			Serializable s = sess.save(new Friend("friend " + i));
			
			//ids.add(s);
			if (i % 1000 == 0) {
				long now = System.currentTimeMillis();
				System.out.println("at " + i);
				
				System.out.println("Took: " + ((now - start) / 1000));
				System.out.println("Free: " + Runtime.getRuntime().freeMemory() / 1024);
				sess.flush();
				start = now;
			}
		}
		tx.commit();
	} catch (HibernateException he) {
	    if (tx!=null) tx.rollback();
	    throw he;
	} finally {
	    sess.close();
	}
	*/
	sess = sf.openSession();
	tx = null;
	
	
	try {
		tx = sess.beginTransaction();
		ids = sess.createQuery("select f.id from " + Friend.class.getName() +" as f")
		.list();
		List a = sess.createCriteria(Friend.class)
			.add(Expression.in("id", ids))
			.list();
		System.out.println(a.size());
		tx.commit();
	} catch (HibernateException he) {
	    if (tx!=null) tx.rollback();
	    throw he;
	} finally {
	    sess.close();
	}
	
	
	
	}
}