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.service; import java.io.IOException; import java.util.ArrayList; import java.util.Date; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.concurrent.LinkedBlockingQueue; import net.sourceforge.subsonic.domain.MediaFile; import org.apache.commons.codec.digest.DigestUtils; import org.apache.http.NameValuePair; import org.apache.http.client.HttpClient; import org.apache.http.client.ResponseHandler; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpGet; import org.apache.http.client.methods.HttpPost; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; import org.apache.http.params.HttpConnectionParams; import net.sourceforge.subsonic.Logger; import net.sourceforge.subsonic.domain.UserSettings; import net.sourceforge.subsonic.util.StringUtil; /** * Provides services for "audioscrobbling", which is the process of * registering what songs are played at www.last.fm. * <p/> * See http://www.last.fm/api/submissions * * @author Sindre Mehus */ public class AudioScrobblerService { private static final Logger LOG = Logger.getLogger(AudioScrobblerService.class); private static final int MAX_PENDING_REGISTRATION = 2000; private static final long MIN_REGISTRATION_INTERVAL = 30000L; private RegistrationThread thread; private final Map<String, Long> lastRegistrationTimes = new HashMap<String, Long>(); private final LinkedBlockingQueue<RegistrationData> queue = new LinkedBlockingQueue<RegistrationData>(); private SettingsService settingsService; /** * Registers the given media file at www.last.fm. This method returns immediately, the actual registration is done * by a separate thread. * * @param mediaFile The media file to register. * @param username The user which played the music file. * @param submission Whether this is a submission or a now playing notification. */ public synchronized void register(MediaFile mediaFile, String username, boolean submission) { if (thread == null) { thread = new RegistrationThread(); thread.start(); } if (queue.size() >= MAX_PENDING_REGISTRATION) { LOG.warn("Last.fm scrobbler queue is full. Ignoring " + mediaFile); return; } RegistrationData registrationData = createRegistrationData(mediaFile, username, submission); if (registrationData == null) { return; } try { queue.put(registrationData); } catch (InterruptedException x) { LOG.warn("Interrupted while queuing Last.fm scrobble.", x); } } /** * Returns registration details, or <code>null</code> if not eligible for registration. */ private RegistrationData createRegistrationData(MediaFile mediaFile, String username, boolean submission) { if (mediaFile == null || mediaFile.isVideo()) { return null; } UserSettings userSettings = settingsService.getUserSettings(username); if (!userSettings.isLastFmEnabled() || userSettings.getLastFmUsername() == null || userSettings.getLastFmPassword() == null) { return null; } long now = System.currentTimeMillis(); // Don't register submissions more often than every 30 seconds. if (submission) { Long lastRegistrationTime = lastRegistrationTimes.get(username); if (lastRegistrationTime != null && now - lastRegistrationTime < MIN_REGISTRATION_INTERVAL) { return null; } lastRegistrationTimes.put(username, now); } RegistrationData reg = new RegistrationData(); reg.username = userSettings.getLastFmUsername(); reg.password = userSettings.getLastFmPassword(); reg.artist = mediaFile.getArtist(); reg.album = mediaFile.getAlbumName(); reg.title = mediaFile.getTitle(); reg.duration = mediaFile.getDurationSeconds() == null ? 0 : mediaFile.getDurationSeconds(); reg.time = new Date(now); reg.submission = submission; return reg; } /** * Scrobbles the given song data at last.fm, using the protocol defined at http://www.last.fm/api/submissions. * * @param registrationData Registration data for the song. */ private void scrobble(RegistrationData registrationData) throws Exception { if (registrationData == null) { return; } String[] lines = authenticate(registrationData); if (lines == null) { return; } String sessionId = lines[1]; String nowPlayingUrl = lines[2]; String submissionUrl = lines[3]; if (registrationData.submission) { lines = registerSubmission(registrationData, sessionId, submissionUrl); } else { lines = registerNowPlaying(registrationData, sessionId, nowPlayingUrl); } if (lines[0].startsWith("FAILED")) { LOG.warn("Failed to scrobble song '" + registrationData.title + "' at Last.fm: " + lines[0]); } else if (lines[0].startsWith("BADSESSION")) { LOG.warn("Failed to scrobble song '" + registrationData.title + "' at Last.fm. Invalid session."); } else if (lines[0].startsWith("OK")) { LOG.debug("Successfully registered " + (registrationData.submission ? "submission" : "now playing") + " for song '" + registrationData.title + "' for user " + registrationData.username + " at Last.fm."); } } /** * Returns the following lines if authentication succeeds: * <p/> * Line 0: Always "OK" * Line 1: Session ID, e.g., "17E61E13454CDD8B68E8D7DEEEDF6170" * Line 2: URL to use for now playing, e.g., "http://post.audioscrobbler.com:80/np_1.2" * Line 3: URL to use for submissions, e.g., "http://post2.audioscrobbler.com:80/protocol_1.2" * <p/> * If authentication fails, <code>null</code> is returned. */ private String[] authenticate(RegistrationData registrationData) throws Exception { String clientId = "sub"; String clientVersion = "0.1"; long timestamp = System.currentTimeMillis() / 1000L; String authToken = calculateAuthenticationToken(registrationData.password, timestamp); String[] lines = executeGetRequest("http://post.audioscrobbler.com/?hs=true&p=1.2.1&c=" + clientId + "&v=" + clientVersion + "&u=" + registrationData.username + "&t=" + timestamp + "&a=" + authToken); if (lines[0].startsWith("BANNED")) { LOG.warn("Failed to scrobble song '" + registrationData.title + "' at Last.fm. Client version is banned."); return null; } if (lines[0].startsWith("BADAUTH")) { LOG.warn("Failed to scrobble song '" + registrationData.title + "' at Last.fm. Wrong username or password."); return null; } if (lines[0].startsWith("BADTIME")) { LOG.warn("Failed to scrobble song '" + registrationData.title + "' at Last.fm. Bad timestamp, please check local clock."); return null; } if (lines[0].startsWith("FAILED")) { LOG.warn("Failed to scrobble song '" + registrationData.title + "' at Last.fm: " + lines[0]); return null; } if (!lines[0].startsWith("OK")) { LOG.warn("Failed to scrobble song '" + registrationData.title + "' at Last.fm. Unknown response: " + lines[0]); return null; } return lines; } private String[] registerSubmission(RegistrationData registrationData, String sessionId, String url) throws IOException { Map<String, String> params = new HashMap<String, String>(); params.put("s", sessionId); params.put("a[0]", registrationData.artist); params.put("t[0]", registrationData.title); params.put("i[0]", String.valueOf(registrationData.time.getTime() / 1000L)); params.put("o[0]", "P"); params.put("r[0]", ""); params.put("l[0]", String.valueOf(registrationData.duration)); params.put("b[0]", registrationData.album); params.put("n[0]", ""); params.put("m[0]", ""); return executePostRequest(url, params); } private String[] registerNowPlaying(RegistrationData registrationData, String sessionId, String url) throws IOException { Map<String, String> params = new HashMap<String, String>(); params.put("s", sessionId); params.put("a", registrationData.artist); params.put("t", registrationData.title); params.put("b", registrationData.album); params.put("l", String.valueOf(registrationData.duration)); params.put("n", ""); params.put("m", ""); return executePostRequest(url, params); } private String calculateAuthenticationToken(String password, long timestamp) { return DigestUtils.md5Hex(DigestUtils.md5Hex(password) + timestamp); } private String[] executeGetRequest(String url) throws IOException { return executeRequest(new HttpGet(url)); } private String[] executePostRequest(String url, Map<String, String> parameters) throws IOException { List<NameValuePair> params = new ArrayList<NameValuePair>(); for (Map.Entry<String, String> entry : parameters.entrySet()) { params.add(new BasicNameValuePair(entry.getKey(), entry.getValue())); } HttpPost request = new HttpPost(url); request.setEntity(new UrlEncodedFormEntity(params, StringUtil.ENCODING_UTF8)); return executeRequest(request); } private String[] executeRequest(HttpUriRequest request) throws IOException { HttpClient client = new DefaultHttpClient(); HttpConnectionParams.setConnectionTimeout(client.getParams(), 15000); HttpConnectionParams.setSoTimeout(client.getParams(), 15000); try { ResponseHandler<String> responseHandler = new BasicResponseHandler(); String response = client.execute(request, responseHandler); return response.split("\\n"); } finally { client.getConnectionManager().shutdown(); } } public void setSettingsService(SettingsService settingsService) { this.settingsService = settingsService; } private class RegistrationThread extends Thread { private RegistrationThread() { super("AudioScrobbler Registration"); } @Override public void run() { while (true) { RegistrationData registrationData = null; try { registrationData = queue.take(); scrobble(registrationData); } catch (IOException x) { handleNetworkError(registrationData, x); } catch (Exception x) { LOG.warn("Error in Last.fm registration.", x); } } } private void handleNetworkError(RegistrationData registrationData, IOException x) { try { queue.put(registrationData); LOG.info( "Last.fm registration for " + registrationData.title + " encountered network error. Will try again later. In queue: " + queue.size(), x); } catch (InterruptedException e) { LOG.error("Failed to reschedule Last.fm registration for " + registrationData.title, e); } try { sleep(15L * 60L * 1000L); // Wait 15 minutes. } catch (InterruptedException e) { LOG.error("Failed to sleep after Last.fm registration failure for " + registrationData.title, e); } } } private static class RegistrationData { private String username; private String password; private String artist; private String album; private String title; private int duration; private Date time; public boolean submission; } }