querytest.java

Hiberante程序高手秘籍的源代码

package com.oreilly.hh;

import net.sf.hibernate.*;
import net.sf.hibernate.cfg.Configuration;

import java.sql.Time;
import java.util.*;

/**
 * Retrieve data as objects
 */
public class QueryTest {

    /**
     * Retrieve any tracks that fit in the specified amount of time.
     *
     * @param length the maximum playing time for tracks to be returned.
     * @param session the Hibernate session that can retrieve data.
     * @return a list of {@link Track}s meeting the length restriction.
     * @throws HibernateException if there is a problem.
     */
    public static List tracksNoLongerThan(Time length, Session session)
        throws HibernateException
    {
        Query query = session.getNamedQuery(
                          "com.oreilly.hh.tracksNoLongerThan");
        query.setTime("length", length);
        return query.list();
    }   

    /**
     * Build a parenthetical, comma-separated list of artist names.
     * @param artists the artists whose names are to be displayed.
     * @return formatted list, or an empty string if the set was empty.
     */
    public static String listArtistNames(Set artists) {
        StringBuffer result = new StringBuffer();
        for (Iterator iter = artists.iterator(); iter.hasNext(); ) {
            Artist artist = (Artist)iter.next();
            result.append((result.length() == 0) ? "(" : ", ");
            result.append(artist.getName());
        }
        if (result.length() > 0) {
            result.append(") ");
        }
        return result.toString();
    }

    /**
     * Look up and print some tracks when invoked from the command line.
     */
    public static void main(String args[]) throws Exception {
        // Create a configuration based on the properties file we've put
        // in the standard place.
        Configuration config = new Configuration();

        // Tell it about the classes we want mapped, taking advantage of
        // the way we've named their mapping documents.
        config.addClass(Track.class).addClass(Artist.class);

        // Get the session factory we can use for persistence
        SessionFactory sessionFactory = config.buildSessionFactory();

        // Ask for a session using the JDBC information we've configured
        Session session = sessionFactory.openSession();
        try {
            // Print the tracks that will fit in seven minutes
            List tracks = tracksNoLongerThan(Time.valueOf("00:07:00"),
                                             session);
            for (ListIterator iter = tracks.listIterator() ;
                 iter.hasNext() ; ) {
                Track aTrack = (Track)iter.next();
                System.out.println("Track: \"" + aTrack.getTitle() + "\" " +
                                   listArtistNames(aTrack.getArtists()) +
                                   aTrack.getPlayTime());
                for (Iterator comIter = aTrack.getComments().iterator() ;
                     comIter.hasNext() ; ) {
                    System.out.println("  Comment: " + comIter.next());
                }
            }
        } finally {
            // No matter what, close the session
            session.close();
        }

        // Clean up after ourselves
        sessionFactory.close();
    }
}