Пример #1
0
  public static long checksumBufferedInputStream(Path filename) throws IOException {
    try (InputStream in = new BufferedInputStream(Files.newInputStream(filename))) {
      CRC32 crc = new CRC32();

      int c;
      while ((c = in.read()) != -1) crc.update(c);
      return crc.getValue();
    }
  }
Пример #2
0
  public static long checksumMappedFile(Path filename) throws IOException {
    try (FileChannel channel = FileChannel.open(filename)) {
      CRC32 crc = new CRC32();
      int length = (int) channel.size();
      MappedByteBuffer buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, length);

      for (int p = 0; p < length; p++) {
        int c = buffer.get(p);
        crc.update(c);
      }
      return crc.getValue();
    }
  }
Пример #3
0
  public static long checksumRandomAccessFile(Path filename) throws IOException {
    try (RandomAccessFile file = new RandomAccessFile(filename.toFile(), "r")) {
      long length = file.length();
      CRC32 crc = new CRC32();

      for (long p = 0; p < length; p++) {
        file.seek(p);
        int c = file.readByte();
        crc.update(c);
      }
      return crc.getValue();
    }
  }