Java tutorial
/* * Computoser is a music-composition algorithm and a website to present the results * Copyright (C) 2012-2014 Bozhidar Bozhanov * * Computoser is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License as * published by the Free Software Foundation, either version 3 of the * License, or (at your option) any later version. * * Computoser is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with Computoser. If not, see <http://www.gnu.org/licenses/>. */ package com.music.service; import java.io.IOException; import java.io.OutputStream; import java.util.ArrayList; import java.util.Comparator; import java.util.List; import java.util.TreeSet; import javax.inject.Inject; import org.springframework.stereotype.Service; import org.springframework.transaction.annotation.Transactional; import com.google.common.primitives.Ints; import com.google.common.primitives.Longs; import com.music.dao.PieceDao; import com.music.model.persistent.Piece; import com.music.model.persistent.PiecePack; @Service public class PiecePackService { @Inject private PieceDao dao; @Inject private PieceService pieceService; @Transactional(readOnly = true) public List<PiecePack> getPiecePacks() { List<PiecePack> packs = dao.listOrdered(PiecePack.class, "priority"); // order pieces in memory, by likes for (PiecePack pack : packs) { TreeSet<Piece> pieces = new TreeSet<>(pieceComparator); pieces.addAll(pack.getPieces()); pack.setPieces(pieces); } return packs; } public static final Comparator<Piece> pieceComparator = new Comparator<Piece>() { @Override public int compare(Piece o1, Piece o2) { int result = Ints.compare(o2.getLikes(), o1.getLikes()); if (result == 0) { result = Longs.compare(o2.getId(), o1.getId()); } return result; } }; @Transactional(readOnly = true) public List<PiecePack> getPiecePacks(ArrayList<Long> ids) { return dao.getByIds(PiecePack.class, ids); } @Transactional public void download(long packId, OutputStream out) throws IOException { PiecePack pack = getPack(packId); pack.setDownloads(pack.getDownloads() + 1); dao.persist(pack); pieceService.downloadPieces(out, pack.getPieces()); } @Transactional(readOnly = true) public PiecePack getPack(long id) { return dao.getById(PiecePack.class, id); } }