コード例 #1
0
  /**
   * Read block from file.
   *
   * @param file - File to read.
   * @param off - Marker position in file to start read from if {@code -1} read last blockSz bytes.
   * @param blockSz - Maximum number of chars to read.
   * @param lastModified - File last modification time.
   * @return Read file block.
   * @throws IOException In case of error.
   */
  public static VisorFileBlock readBlock(File file, long off, int blockSz, long lastModified)
      throws IOException {
    RandomAccessFile raf = null;

    try {
      long fSz = file.length();
      long fLastModified = file.lastModified();

      long pos = off >= 0 ? off : Math.max(fSz - blockSz, 0);

      // Try read more that file length.
      if (fLastModified == lastModified && fSz != 0 && pos >= fSz)
        throw new IOException(
            "Trying to read file block with wrong offset: " + pos + " while file size: " + fSz);

      if (fSz == 0)
        return new VisorFileBlock(file.getPath(), pos, fLastModified, 0, false, EMPTY_FILE_BUF);
      else {
        int toRead = Math.min(blockSz, (int) (fSz - pos));

        byte[] buf = new byte[toRead];

        raf = new RandomAccessFile(file, "r");

        raf.seek(pos);

        int cntRead = raf.read(buf, 0, toRead);

        if (cntRead != toRead)
          throw new IOException(
              "Count of requested and actually read bytes does not match [cntRead="
                  + cntRead
                  + ", toRead="
                  + toRead
                  + ']');

        boolean zipped = buf.length > 512;

        return new VisorFileBlock(
            file.getPath(), pos, fSz, fLastModified, zipped, zipped ? zipBytes(buf) : buf);
      }
    } finally {
      U.close(raf, null);
    }
  }
コード例 #2
0
  /**
   * Decode file charset.
   *
   * @param f File to process.
   * @return File charset.
   * @throws IOException in case of error.
   */
  public static Charset decode(File f) throws IOException {
    SortedMap<String, Charset> charsets = Charset.availableCharsets();

    String[] firstCharsets = {
      Charset.defaultCharset().name(), "US-ASCII", "UTF-8", "UTF-16BE", "UTF-16LE"
    };

    Collection<Charset> orderedCharsets = U.newLinkedHashSet(charsets.size());

    for (String c : firstCharsets)
      if (charsets.containsKey(c)) orderedCharsets.add(charsets.get(c));

    orderedCharsets.addAll(charsets.values());

    try (RandomAccessFile raf = new RandomAccessFile(f, "r")) {
      FileChannel ch = raf.getChannel();

      ByteBuffer buf = ByteBuffer.allocate(4096);

      ch.read(buf);

      buf.flip();

      for (Charset charset : orderedCharsets) {
        CharsetDecoder decoder = charset.newDecoder();

        decoder.reset();

        try {
          decoder.decode(buf);

          return charset;
        } catch (CharacterCodingException ignored) {
        }
      }
    }

    return Charset.defaultCharset();
  }