3.2. Finding Persistent Objects
It's time to throw the giant lever into reverse and look at how you load data from a database into Java objects.
Use Hibernate Query Language to get an object-oriented view of the contents of your mapped database tables. These might have started out as objects persisted in a previous session, or they might be data that came from completely outside your application code.
3.1.1. How do I do that?
Example 3-5 shows a program that runs a simple query using the test data we just created. The overall structure will look very familiar, because all the Hibernate setup is the same as the previous program.
Example 3-5. QueryTest.java
1 package com.oreilly.hh;
2
3 import net.sf.hibernate.*;
4 import net.sf.hibernate.cfg.Configuration;
5
6 import java.sql.Time;
7 import java.util.*;
8
9 /**
10 * Retrieve data as objects
11 */
12 public class QueryTest {
13
14 /**
15 * Retrieve any tracks that fit in the specified amount of time.
16 *
17 * @param length the maximum playing time for tracks to be returned.
18 * @param session the Hibernate session that can retrieve data. 19 * @return a list of {@link Track}s meeting the length restriction. 20 * @throws HibernateException if there is a problem. 21 */ 22 public static List tracksNoLongerThan(Time length, Session session) 23 throws HibernateException 24 { 25 return session.find("from com.oreilly.hh.Track as track " + 26 "where track.playTime <= ?", 27 length, Hibernate.TIME); 28 } 29 30 /** 31 * Look up and print some ... |
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