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 org.madsonic.io; import org.madsonic.Logger; import org.madsonic.domain.MediaFile; import org.madsonic.domain.PlayQueue; import org.madsonic.service.SettingsService; import org.apache.commons.lang.StringUtils; import java.io.IOException; import java.io.OutputStream; import java.io.UnsupportedEncodingException; /** * Implements SHOUTcast support by decorating an existing output stream. * <p/> * Based on protocol description found on * <em>http://www.smackfu.com/stuff/programming/shoutcast.html</em> * * @author Sindre Mehus */ public class ShoutCastOutputStream extends OutputStream { private static final Logger LOG = Logger.getLogger(ShoutCastOutputStream.class); /** * Number of bytes between each SHOUTcast metadata block. */ public static final int META_DATA_INTERVAL = 20480; /** * The underlying output stream to decorate. */ private OutputStream out; /** * What to write in the SHOUTcast metadata is fetched from the playlist. */ private PlayQueue playQueue; /** * Keeps track of the number of bytes written (excluding meta-data). Between 0 and {@link #META_DATA_INTERVAL}. */ private int byteCount; /** * The last stream title sent. */ private String previousStreamTitle; private SettingsService settingsService; /** * Creates a new SHOUTcast-decorated stream for the given output stream. * * @param out The output stream to decorate. * @param playQueue Meta-data is fetched from this playlist. */ public ShoutCastOutputStream(OutputStream out, PlayQueue playQueue, SettingsService settingsService) { this.out = out; this.playQueue = playQueue; this.settingsService = settingsService; } /** * Writes the given byte array to the underlying stream, adding SHOUTcast meta-data as necessary. */ public void write(byte[] b, int off, int len) throws IOException { int bytesWritten = 0; while (bytesWritten < len) { // 'n' is the number of bytes to write before the next potential meta-data block. int n = Math.min(len - bytesWritten, ShoutCastOutputStream.META_DATA_INTERVAL - byteCount); out.write(b, off + bytesWritten, n); bytesWritten += n; byteCount += n; // Reached meta-data block? if (byteCount % ShoutCastOutputStream.META_DATA_INTERVAL == 0) { writeMetaData(); byteCount = 0; } } } /** * Writes the given byte array to the underlying stream, adding SHOUTcast meta-data as necessary. */ public void write(byte[] b) throws IOException { write(b, 0, b.length); } /** * Writes the given byte to the underlying stream, adding SHOUTcast meta-data as necessary. */ public void write(int b) throws IOException { byte[] buf = new byte[] { (byte) b }; write(buf); } /** * Flushes the underlying stream. */ public void flush() throws IOException { out.flush(); } /** * Closes the underlying stream. */ public void close() throws IOException { out.close(); } private void writeMetaData() throws IOException { String streamTitle = StringUtils.trimToEmpty(settingsService.getWelcomeTitle()); MediaFile result; synchronized (playQueue) { result = playQueue.getCurrentFile(); } MediaFile mediaFile = result; if (mediaFile != null) { streamTitle = mediaFile.getArtist() + " - " + mediaFile.getTitle(); } byte[] bytes; if (streamTitle.equals(previousStreamTitle)) { bytes = new byte[0]; } else { try { previousStreamTitle = streamTitle; bytes = createStreamTitle(streamTitle); } catch (UnsupportedEncodingException x) { LOG.warn("Failed to create SHOUTcast meta-data. Ignoring.", x); bytes = new byte[0]; } } // Length in groups of 16 bytes. int length = bytes.length / 16; if (bytes.length % 16 > 0) { length++; } // Write the length as a single byte. out.write(length); // Write the message. out.write(bytes); // Write padding zero bytes. int padding = length * 16 - bytes.length; for (int i = 0; i < padding; i++) { out.write(0); } } private byte[] createStreamTitle(String title) throws UnsupportedEncodingException { // Remove any quotes from the title. title = title.replaceAll("'", ""); // Convert non-ascii characters to similar ascii characters. for (char[] chars : ShoutCastOutputStream.CHAR_MAP) { title = title.replace(chars[0], chars[1]); } title = "StreamTitle='" + title + "';"; return title.getBytes("US-ASCII"); } /** * Maps from miscellaneous accented characters to similar-looking ASCII characters. */ private static final char[][] CHAR_MAP = { { '\u00C0', 'A' }, { '\u00C1', 'A' }, { '\u00C2', 'A' }, { '\u00C3', 'A' }, { '\u00C4', 'A' }, { '\u00C5', 'A' }, { '\u00C6', 'A' }, { '\u00C8', 'E' }, { '\u00C9', 'E' }, { '\u00CA', 'E' }, { '\u00CB', 'E' }, { '\u00CC', 'I' }, { '\u00CD', 'I' }, { '\u00CE', 'I' }, { '\u00CF', 'I' }, { '\u00D2', 'O' }, { '\u00D3', 'O' }, { '\u00D4', 'O' }, { '\u00D5', 'O' }, { '\u00D6', 'O' }, { '\u00D9', 'U' }, { '\u00DA', 'U' }, { '\u00DB', 'U' }, { '\u00DC', 'U' }, { '\u00DF', 'B' }, { '\u00E0', 'a' }, { '\u00E1', 'a' }, { '\u00E2', 'a' }, { '\u00E3', 'a' }, { '\u00E4', 'a' }, { '\u00E5', 'a' }, { '\u00E6', 'a' }, { '\u00E7', 'c' }, { '\u00E8', 'e' }, { '\u00E9', 'e' }, { '\u00EA', 'e' }, { '\u00EB', 'e' }, { '\u00EC', 'i' }, { '\u00ED', 'i' }, { '\u00EE', 'i' }, { '\u00EF', 'i' }, { '\u00F1', 'n' }, { '\u00F2', 'o' }, { '\u00F3', 'o' }, { '\u00F4', 'o' }, { '\u00F5', 'o' }, { '\u00F6', 'o' }, { '\u00F8', 'o' }, { '\u00F9', 'u' }, { '\u00FA', 'u' }, { '\u00FB', 'u' }, { '\u00FC', 'u' }, { '\u2013', '-' } }; }