Java tutorial
/* This file is part of Subsonic. Subsonic is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. Subsonic 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 General Public License for more details. You should have received a copy of the GNU General Public License along with Subsonic. If not, see <http://www.gnu.org/licenses/>. Copyright 2009 (C) Sindre Mehus */ package net.sourceforge.subsonic.dao; import java.util.ArrayList; import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Map; import org.springframework.dao.EmptyResultDataAccessException; import net.sourceforge.subsonic.domain.MediaFile; import net.sourceforge.subsonic.domain.MusicFolder; import static net.sourceforge.subsonic.domain.MediaFile.MediaType.ALBUM; /** * Provides database services for ratings. * * @author Sindre Mehus */ public class RatingDao extends AbstractDao { /** * Returns paths for the highest rated albums. * * @param offset Number of albums to skip. * @param count Maximum number of albums to return. * @param musicFolders Only return albums in these folders. * @return Paths for the highest rated albums. */ public List<String> getHighestRatedAlbums(final int offset, final int count, final List<MusicFolder> musicFolders) { if (count < 1 || musicFolders.isEmpty()) { return Collections.emptyList(); } Map<String, Object> args = new HashMap<String, Object>() { { put("type", ALBUM.name()); put("folders", MusicFolder.toPathList(musicFolders)); put("count", count); put("offset", offset); } }; String sql = "select user_rating.path from user_rating, media_file " + "where user_rating.path=media_file.path and media_file.present and media_file.type = :type and media_file.folder in (:folders) " + "group by path " + "order by avg(rating) desc limit :count offset :offset"; return namedQueryForStrings(sql, args); } /** * Sets the rating for a media file and a given user. * * @param username The user name. * @param mediaFile The media file. * @param rating The rating between 1 and 5, or <code>null</code> to remove the rating. */ public void setRatingForUser(String username, MediaFile mediaFile, Integer rating) { if (rating != null && (rating < 1 || rating > 5)) { return; } update("delete from user_rating where username=? and path=?", username, mediaFile.getPath()); if (rating != null) { update("insert into user_rating values(?, ?, ?)", username, mediaFile.getPath(), rating); } } /** * Returns the average rating for the given media file. * * @param mediaFile The media file. * @return The average rating, or <code>null</code> if no ratings are set. */ public Double getAverageRating(MediaFile mediaFile) { try { return (Double) getJdbcTemplate().queryForObject("select avg(rating) from user_rating where path=?", new Object[] { mediaFile.getPath() }, Double.class); } catch (EmptyResultDataAccessException x) { return null; } } /** * Returns the rating for the given user and media file. * * @param username The user name. * @param mediaFile The media file. * @return The rating, or <code>null</code> if no rating is set. */ public Integer getRatingForUser(String username, MediaFile mediaFile) { try { return getJdbcTemplate().queryForInt("select rating from user_rating where username=? and path=?", new Object[] { username, mediaFile.getPath() }); } catch (EmptyResultDataAccessException x) { return null; } } public int getRatedAlbumCount(final String username, final List<MusicFolder> musicFolders) { if (musicFolders.isEmpty()) { return 0; } Map<String, Object> args = new HashMap<String, Object>() { { put("type", ALBUM.name()); put("folders", MusicFolder.toPathList(musicFolders)); put("username", username); } }; return namedQueryForInt( "select count(*) from user_rating, media_file " + "where media_file.path = user_rating.path " + "and media_file.type = :type " + "and media_file.present " + "and media_file.folder in (:folders) " + "and user_rating.username = :username", 0, args); } }