Java Code Examples for java.io.RandomAccessFile#length()

public static void main(String... args) throws IOException {
    String fileName = args[0];
    long position = Integer.parseInt(args[1]);

    String text = args[2];

    RandomAccessFile file = new RandomAccessFile(fileName, "rw");
    position = position > file.length() ? file.length() : position;
    file.seek(position);
    file.write(text.getBytes());
    file.close();


}
 

private static void largeFile(String fileName) throws IOException {
    if (!new File(fileName).exists()) {
        System.out.println("not found: " + fileName);
        return;
    }
    RandomAccessFile f = new RandomAccessFile(fileName, "r");
    byte[] data = new byte[(int) f.length()];
    f.readFully(data);
    HashSet<Text> set = new HashSet<Text>(40 * 1024 * 1024);
    int end = Text.indexOf(data, 0, '\n');
    Text t = new Text(data, 0, end);
    long time = System.currentTimeMillis();
    while (true) {
        set.add(t);
        if (end >= data.length - 1) {
            break;
        }
        int start = end + 1;
        end = Text.indexOf(data, start, '\n');
        t = new Text(data, start, end - start);
        long now = System.currentTimeMillis();
        if (now - time > 2000) {
            System.out.println("size: " + set.size());
            time = now;
        }
    }
    System.out.println("file: " + fileName);
    System.out.println("size: " + set.size());

    test(set, 8, 14);
    test(set, 8, 10);
    test(set, 8, 16);
    test(set, 8, 12);
}
 

/**
 * 将表示此设备在该程序上的唯一标识符写入程序文件系统中。
 *
 * @param installation 保存唯一标识符的File对象。
 * @return 唯一标识符。
 * @throws java.io.IOException IO异常。
 */
private static String readInstallationFile(File installation) throws IOException {
    RandomAccessFile accessFile = new RandomAccessFile(installation, "r");
    byte[] bs = new byte[(int) accessFile.length()];
    accessFile.readFully(bs);
    accessFile.close();
    return new String(bs);
}
 

private static void write_sector(RandomAccessFile f, int[] buf, int startOffset) throws IOException {
	byte[] bytes = new byte[512];
	ByteBuffer.wrap(bytes).order(ByteOrder.LITTLE_ENDIAN).asIntBuffer().put(buf, startOffset, 128);
	if (Arrays.equals(bytes, MAGIC_TRIM_SECTOR)) {
		if (f.length() > f.getFilePointer())
			f.setLength(f.getFilePointer());
		return;
	}
	f.write(bytes);
}
 

private void setDumpBuffer(RandomAccessFile file) throws IOException {
    long length = file.length();

    try {
        if (length > Integer.MAX_VALUE) {
            dumpBuffer = new LongMemoryMappedData(file, length, ENTRY_SIZE);
        } else {
            dumpBuffer = new MemoryMappedData(file, length);
        }
    } catch (IOException ex) {
        if (ex.getCause() instanceof OutOfMemoryError) {
            dumpBuffer = new FileData(file, length);
        } else {
            throw ex;
        }
    }
}
 

private void transferLog(RandomAccessFile logFile, SocketChannel sChannel, int index) {
	try {
		long totalBytes = logFile.length();
		System.out.println("---Called transferLog." + totalBytes + " " + (sChannel == null));
		FileChannel fileChannel = logFile.getChannel();
		long bytesTransfered = 0;
		while (bytesTransfered < totalBytes) {
			long bufferSize = 65536;
			if (totalBytes - bytesTransfered < bufferSize) {
				bufferSize = (int) (totalBytes - bytesTransfered);
				if (bufferSize <= 0)
					bufferSize = (int) totalBytes;
			}
			long bytesSent = fileChannel.transferTo(bytesTransfered, bufferSize, sChannel);
			if (bytesSent > 0) {
				bytesTransfered += bytesSent;
			}
		}
	} catch (Exception e) {
		e.printStackTrace();
		System.err.println("State recover was aborted due to an unexpected exception");
	}
}
 

/**
 * Check to see if a pattern matches the saved pattern. If no pattern
 * exists, always returns true.
 * 
 * @param pattern
 *            The pattern to check.
 * @return Whether the pattern matches the stored one.
 */
public boolean checkPattern(List<LockPatternView.Cell> pattern) {
	try {
		// Read all the bytes from the file
		RandomAccessFile raf = new RandomAccessFile(sLockPatternFilename,
				"r");
		final byte[] stored = new byte[(int) raf.length()];
		int got = raf.read(stored, 0, stored.length);
		raf.close();
		if (got <= 0) {
			return true;
		}
		// Compare the hash from the file with the entered pattern's hash
		return Arrays.equals(stored,
				LockPatternUtils.patternToHash(pattern));
	} catch (FileNotFoundException fnfe) {
		return true;
	} catch (IOException ioe) {
		return true;
	}
}
 

private void passN() throws IOException
{

    // Get FV from file
    randomAccessFile = new RandomAccessFile(getCacheFile(), "r");

    while (randomAccessFile.getFilePointer() < randomAccessFile.length())
    {
        int recordLength = (int) randomAccessFile.readLong();
        packBuffer = growIfNeeded(packBuffer, recordLength);
        randomAccessFile.read(packBuffer, 0, recordLength);
        FeatureVector fv = toFeatureVector();
        // add to ring buffer
        addWithProb(fv);

    }

    randomAccessFile.close();

    signalEndEpoch();

}
 

/**
 * Corrupt the specified file.  Some random bytes within the file
 * will be changed to some random values.
 *
 * @throws IllegalArgumentException if the given file is not a file
 * @throws IOException if an IOException occurs while reading or writing the file
 */
public static void corruptFile(File file) throws IOException {
  if (!file.isFile()) {
    throw new IllegalArgumentException(
                                       "Given argument is not a file:" + file);
  }
  RandomAccessFile raf = new RandomAccessFile(file,"rws");
  Random random = new Random();
  for (long i = 0; i < raf.length(); i++) {
    raf.seek(i);
    if (random.nextBoolean()) {
      raf.writeByte(random.nextInt());
    }
  }
  raf.close();
}
 

@Override
public long truncateFileAtURL(LocalFilesystemURL inputURL, long size) throws IOException {
       File file = new File(filesystemPathForURL(inputURL));

       if (!file.exists()) {
           throw new FileNotFoundException("File at " + inputURL.URL + " does not exist.");
       }
       
       RandomAccessFile raf = new RandomAccessFile(filesystemPathForURL(inputURL), "rw");
       try {
           if (raf.length() >= size) {
               FileChannel channel = raf.getChannel();
               channel.truncate(size);
               return size;
           }

           return raf.length();
       } finally {
           raf.close();
       }


}
 

private static String readInstallationFile(File installation) throws IOException {
    RandomAccessFile f = new RandomAccessFile(installation, "r");
    byte[] bytes = new byte[(int) f.length()];
    f.readFully(bytes);
    f.close();
    return new String(bytes);
}
 

/**
 * 追加文件：使用RandomAccessFile
 */
public static void appendMethodA(String fileName, String content) {
	try {
		// 打开一个随机访问文件流，按读写方式
		RandomAccessFile randomFile = new RandomAccessFile(fileName, "rw");
		// 文件长度，字节数
		long fileLength = randomFile.length();
		// 将写文件指针移到文件尾。
		randomFile.seek(fileLength);
		randomFile.writeBytes(content);
		randomFile.close();
	} catch (IOException e) {
		e.printStackTrace();
	}
}
 

public static boolean checkFileFormat(RandomAccessFile file)
    throws IOException {
  if (file.length() < Loader.MINIMUM_FILE_LENGTH)
    return false;

  byte[] magic = new byte[MAGIC_HEADER.length];
  file.readFully(magic);
  if (!Arrays.equals(MAGIC_HEADER, magic))
    return false;

  return true;
}
 

/**
 * Returns the ZIP End of Central Directory record of the provided ZIP file.
 *
 * @return contents of the ZIP End of Central Directory record and the record's offset in the
 *         file or {@code null} if the file does not contain the record.
 *
 * @throws IOException if an I/O error occurs while reading the file.
 */
static Pair<ByteBuffer, Long> findZipEndOfCentralDirectoryRecord(RandomAccessFile zip)
        throws IOException {
    // ZIP End of Central Directory (EOCD) record is located at the very end of the ZIP archive.
    // The record can be identified by its 4-byte signature/magic which is located at the very
    // beginning of the record. A complication is that the record is variable-length because of
    // the comment field.
    // The algorithm for locating the ZIP EOCD record is as follows. We search backwards from
    // end of the buffer for the EOCD record signature. Whenever we find a signature, we check
    // the candidate record's comment length is such that the remainder of the record takes up
    // exactly the remaining bytes in the buffer. The search is bounded because the maximum
    // size of the comment field is 65535 bytes because the field is an unsigned 16-bit number.

    long fileSize = zip.length();
    if (fileSize < ZIP_EOCD_REC_MIN_SIZE) {
        return null;
    }

    // Optimization: 99.99% of APKs have a zero-length comment field in the EoCD record and thus
    // the EoCD record offset is known in advance. Try that offset first to avoid unnecessarily
    // reading more data.
    Pair<ByteBuffer, Long> result = findZipEndOfCentralDirectoryRecord(zip, 0);
    if (result != null) {
        return result;
    }

    // EoCD does not start where we expected it to. Perhaps it contains a non-empty comment
    // field. Expand the search. The maximum size of the comment field in EoCD is 65535 because
    // the comment length field is an unsigned 16-bit number.
    return findZipEndOfCentralDirectoryRecord(zip, UINT16_MAX_VALUE);
}
 

public static boolean checkFileFormat(RandomAccessFile file)
    throws IOException {
  if (file.length() < Loader.MINIMUM_FILE_LENGTH)
    return false;

  byte[] magic = new byte[MAGIC_HEADER.length];
  file.readFully(magic);
  if (!Arrays.equals(MAGIC_HEADER, magic))
    return false;

  return true;
}
 

private static byte[] readFile(String fileName) throws IOException {
    RandomAccessFile f = new RandomAccessFile(fileName, "r");
    byte[] data = new byte[(int) f.length()];
    f.readFully(data);
    f.close();
    return data;
}
 

public int write(AudioInputStream stream, AudioFileFormat.Type fileType, File out) throws IOException {

        // throws IllegalArgumentException if not supported
        AuFileFormat auFileFormat = (AuFileFormat)getAudioFileFormat(fileType, stream);

        // first write the file without worrying about length fields
        FileOutputStream fos = new FileOutputStream( out );     // throws IOException
        BufferedOutputStream bos = new BufferedOutputStream( fos, bisBufferSize );
        int bytesWritten = writeAuFile(stream, auFileFormat, bos );
        bos.close();

        // now, if length fields were not specified, calculate them,
        // open as a random access file, write the appropriate fields,
        // close again....
        if( auFileFormat.getByteLength()== AudioSystem.NOT_SPECIFIED ) {

            // $$kk: 10.22.99: jan: please either implement this or throw an exception!
            // $$fb: 2001-07-13: done. Fixes Bug 4479981
            RandomAccessFile raf=new RandomAccessFile(out, "rw");
            if (raf.length()<=0x7FFFFFFFl) {
                // skip AU magic and data offset field
                raf.skipBytes(8);
                raf.writeInt(bytesWritten-AuFileFormat.AU_HEADERSIZE);
                // that's all
            }
            raf.close();
        }

        return bytesWritten;
    }
 

private void openLogFile() {
  try {
    logWriter   = new RandomAccessFile( this.logFile, "rw" );
    logFileSize = logWriter.length();
    logWriter.seek( logFileSize );
  } catch (Exception e) {
    logWriter = null;
  }
}
 

public void channelActive(ChannelHandlerContext ctx) {
	try {
		File file=new File(filePath);
		
		randomAccessFile = new RandomAccessFile(file, "r");
		randomAccessFile.seek(0);

		if ((randomAccessFile.length() % dataLength) == 0) {
			sumCountpackage = (int) (randomAccessFile.length() / dataLength);
		} else {
			sumCountpackage = (int) (randomAccessFile.length() / dataLength) + 1;
		}
		byte[] bytes = new byte[dataLength];
		
		LOGGER.debug("文件总长度:"+randomAccessFile.length());
		if (randomAccessFile.read(bytes) != -1) {
			EchoFile msgFile = new EchoFile();
			msgFile.setSumCountPackage(sumCountpackage);
			msgFile.setCountPackage(1);
			msgFile.setBytes(bytes);
			msgFile.setFile_md5(file.getName());
			ctx.writeAndFlush(msgFile);
			

		} else {
			System.out.println("文件已经读完");
		}
	} catch (FileNotFoundException e) {
		e.printStackTrace();
	} catch (IOException i) {
		i.printStackTrace();
	}
}
 

public ZipInput( String filename) throws IOException
{
    this.inputFilename = filename;
    in = new RandomAccessFile( new File( inputFilename), "r");
    fileLength = in.length();
}