src/main/java/net/pterodactylus/sonitus/io/IdentifyingInputStream.java

   1 /*
   2  * Sonitus - IdentifyingStream.java - Copyright © 2013 David Roden
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package net.pterodactylus.sonitus.io;
  19
  20 import java.io.FilterInputStream;
  21 import java.io.IOException;
  22 import java.io.InputStream;
  23
  24 import net.pterodactylus.sonitus.data.Format;
  25
  26 import com.google.common.base.Optional;
  27
  28 /**
  29  * Wrapper around an {@link InputStream} that identifies the {@link Format} of
  30  * the wrapped stream.
  31  *
  32  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  33  */
  34 public class IdentifyingInputStream extends FilterInputStream {
  35
  36         /** The identified format. */
  37         private final Format format;
  38
  39         /**
  40          * Creates a new identifying input stream.
  41          *
  42          * @param inputStream
  43          *              The input stream to wrap
  44          * @param format
  45          *              The format of the stream
  46          */
  47         private IdentifyingInputStream(InputStream inputStream, Format format) {
  48                 super(inputStream);
  49                 this.format = format;
  50         }
  51
  52         //
  53         // ACCESSORS
  54         //
  55
  56         /**
  57          * Returns the identified format.
  58          *
  59          * @return The identified format
  60          */
  61         public Format format() {
  62                 return format;
  63         }
  64
  65         //
  66         // STATIC METHODS
  67         //
  68
  69         /**
  70          * Tries to identify the given input stream.
  71          *
  72          * @param inputStream
  73          *              The input stream to identify
  74          * @return An identifying input stream that delivers the original stream and
  75          *         the format it detected, or {@link com.google.common.base.Optional#absent()}
  76          *         if no format could be identified
  77          * @throws IOException
  78          *              if an I/O error occurs
  79          */
  80         public static Optional<IdentifyingInputStream> create(InputStream inputStream) throws IOException {
  81
  82                 /* remember everything we read here. */
  83                 RememberingInputStream rememberingInputStream = new RememberingInputStream(inputStream);
  84
  85                 /* try Ogg Vorbis first. */
  86                 Optional<Format> format = OggVorbisIdentifier.identify(rememberingInputStream);
  87                 if (format.isPresent()) {
  88                         return Optional.of(new IdentifyingInputStream(rememberingInputStream.remembered(), format.get()));
  89                 }
  90
  91                 return Optional.absent();
  92         }
  93
  94 }