Example usage for java.io RandomAccessFile seek

List of usage examples for java.io RandomAccessFile seek

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Introduction

In this page you can find the example usage for java.io RandomAccessFile seek.

Prototype

public void seek(long pos) throws IOException

Source Link

Document

Sets the file-pointer offset, measured from the beginning of this file, at which the next read or write occurs.

Usage

From source file:Main.java

public static byte[] readFromFile(String fileName, int offset, int len) {
    if (fileName == null) {
        return null;
    }/*from  w  w w.j av  a2 s  .c  o m*/

    File file = new File(fileName);
    if (!file.exists()) {
        //WLog.i(FileUtils.class, "readFromFile: file not found");
        return null;
    }

    if (len == -1) {
        len = (int) file.length();
    }

    if (offset < 0) {
        //WLog.e(FileUtils.class, "readFromFile invalid offset:" + offset);
        return null;
    }
    if (len <= 0) {
        //WLog.e(FileUtils.class, "readFromFile invalid len:" + len);
        return null;
    }
    if (offset + len > (int) file.length()) {
        //WLog.e(FileUtils.class, "readFromFile invalid file len:" + file.length());
        return null;
    }

    byte[] b = null;
    try {
        RandomAccessFile in = new RandomAccessFile(fileName, "r");
        b = new byte[len];
        in.seek(offset);
        in.readFully(b);
        in.close();

    } catch (Exception e) {
        // WLog.e(FileUtils.class, "readFromFile : errMsg = " + e.getMessage());
        e.printStackTrace();
    }
    return b;
}

From source file:Main.java

public static byte[] readFromFile(String fileName, int offset, int len) {
    if (fileName == null) {
        return null;
    }//from   www. j av a2 s . c  o  m

    File file = new File(fileName);
    if (!file.exists()) {
        Log.i(TAG, "readFromFile: file not found");
        return null;
    }

    if (len == -1) {
        len = (int) file.length();
    }

    Log.d(TAG, "readFromFile : offset = " + offset + " len = " + len + " offset + len = " + (offset + len));

    if (offset < 0) {
        Log.e(TAG, "readFromFile invalid offset:" + offset);
        return null;
    }
    if (len <= 0) {
        Log.e(TAG, "readFromFile invalid len:" + len);
        return null;
    }
    if (offset + len > (int) file.length()) {
        Log.e(TAG, "readFromFile invalid file len:" + file.length());
        return null;
    }

    byte[] b = null;
    try {
        RandomAccessFile in = new RandomAccessFile(fileName, "r");
        b = new byte[len];
        in.seek(offset);
        in.readFully(b);
        in.close();

    } catch (Exception e) {
        Log.e(TAG, "readFromFile : errMsg = " + e.getMessage());
        e.printStackTrace();
    }
    return b;
}

From source file:Main.java

public static byte[] readFromFile(String fileName, int offset, int len) {
    if (fileName == null) {
        return null;
    }/* www . j a  v  a 2s  .  c  om*/

    File file = new File(fileName);
    if (!file.exists()) {
        Log.i(TAG, "readFromFile: file not found");
        return null;
    }

    if (len == -1) {
        len = (int) file.length();
    }

    Log.d(TAG, "readFromFile : offset = " + offset + " len = " + len + " offset + len = " + (offset + len));

    if (offset < 0) {
        Log.e(TAG, "readFromFile invalid offset:" + offset);
        return null;
    }
    if (len <= 0) {
        Log.e(TAG, "readFromFile invalid len:" + len);
        return null;
    }
    if (offset + len > (int) file.length()) {
        Log.e(TAG, "readFromFile invalid file len:" + file.length());
        return null;
    }

    byte[] b = null;
    try {
        RandomAccessFile in = new RandomAccessFile(fileName, "r");
        b = new byte[len]; //
        in.seek(offset);
        in.readFully(b);
        in.close();

    } catch (Exception e) {
        Log.e(TAG, "readFromFile : errMsg = " + e.getMessage());
        e.printStackTrace();
    }
    return b;
}

From source file:org.movsim.MovsimCoreMainWithExperiments.java

private static void appendFiles(File src, File dst, boolean writeFirstLine) throws IOException {

    LineIterator lIter = FileUtils.lineIterator(src);
    RandomAccessFile rFile = new RandomAccessFile(dst, "rw");

    rFile.seek(dst.length());

    long lineCount = 1;
    while (lIter.hasNext()) {
        String line = lIter.next();

        if (lineCount > 1 || writeFirstLine) {
            rFile.write((line + "\n").getBytes());
        }//from www .  j  a v a2 s . co m
        lineCount++;
    }
    lIter.close();
    rFile.close();
}

From source file:org.apache.hadoop.hdfs.server.namenode.FSImageUtil.java

public static FileSummary loadSummary(RandomAccessFile file) throws IOException {
    final int FILE_LENGTH_FIELD_SIZE = 4;
    long fileLength = file.length();
    file.seek(fileLength - FILE_LENGTH_FIELD_SIZE);
    int summaryLength = file.readInt();

    if (summaryLength <= 0) {
        throw new IOException("Negative length of the file");
    }/*from   w w w.  ja v  a 2  s.c om*/
    file.seek(fileLength - FILE_LENGTH_FIELD_SIZE - summaryLength);

    byte[] summaryBytes = new byte[summaryLength];
    file.readFully(summaryBytes);

    FileSummary summary = FileSummary.parseDelimitedFrom(new ByteArrayInputStream(summaryBytes));
    if (summary.getOndiskVersion() != FILE_VERSION) {
        throw new IOException("Unsupported file version " + summary.getOndiskVersion());
    }

    if (!NameNodeLayoutVersion.supports(Feature.PROTOBUF_FORMAT, summary.getLayoutVersion())) {
        throw new IOException("Unsupported layout version " + summary.getLayoutVersion());
    }
    return summary;
}

From source file:net.yacy.document.parser.tarParser.java

public final static boolean isTar(File f) {
    if (!f.exists() || f.length() < 0x105)
        return false;
    RandomAccessFile raf = null;
    try {/* w w w .  java2s  .com*/
        raf = new RandomAccessFile(f, "r");
        raf.seek(0x101);
        byte[] b = new byte[5];
        raf.read(b);
        return MAGIC.equals(UTF8.String(b));
    } catch (final FileNotFoundException e) {
        return false;
    } catch (final IOException e) {
        return false;
    } finally {
        if (raf != null)
            try {
                raf.close();
            } catch (final IOException e) {
            }
    }
}

From source file:shootersubdownloader.Shootersubdownloader.java

static String computefilehash(File f) throws Exception {
    if (!f.exists() || f.length() < 8 * 1024) {
        return null;
    }//from   w  w w  . ja va 2  s.  c o  m
    long l = f.length();
    long[] offset = new long[4];
    offset[3] = l - 8 * 1024;
    offset[2] = l / 3;
    offset[1] = l / 3 * 2;
    offset[0] = 4 * 1024;
    byte[] bBuf = new byte[1024 * 4];
    RandomAccessFile raf = new RandomAccessFile(f, "r");
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < 4; i++) {
        raf.seek(offset[i]);
        int readlen = raf.read(bBuf, 0, 4 * 1024);
        String md5 = md5(bBuf);
        if (sb.length() != 0) {
            sb.append("%3B");
        }
        sb.append(md5);
    }
    raf.close();
    return sb.toString();
}

From source file:org.mycontroller.standalone.api.jaxrs.utils.McServerLogFile.java

public static LogFileJson getLogUpdate(Long lastKnownPosition, Long lastNPosition) {
    if (lastNPosition != null && appLogFile.length() > lastNPosition) {
        lastKnownPosition = appLogFile.length() - lastNPosition;
    } else if (lastKnownPosition != null && appLogFile.length() <= lastKnownPosition) {
        return LogFileJson.builder().lastKnownPosition(lastKnownPosition).build();
    }//from  w ww.  j ava2 s  . c o  m
    if (lastKnownPosition == null) {
        lastKnownPosition = 0l;
    }

    //Set maximum limit
    if ((appLogFile.length() - lastKnownPosition) > MAX_POSITION_LIMIT) {
        lastKnownPosition = appLogFile.length() - MAX_POSITION_LIMIT;
    }

    logBuilder.setLength(0);
    // Reading and writing file
    RandomAccessFile readFileAccess = null;
    try {
        readFileAccess = new RandomAccessFile(appLogFile, "r");
        readFileAccess.seek(lastKnownPosition);
        String log = null;
        while ((log = readFileAccess.readLine()) != null) {
            logBuilder.append(log).append("\n");
        }
        lastKnownPosition = readFileAccess.getFilePointer();
    } catch (FileNotFoundException ex) {
        _logger.error("Error,", ex);
    } catch (IOException ex) {
        _logger.error("Error,", ex);
    } finally {
        if (readFileAccess != null) {
            try {
                readFileAccess.close();
            } catch (IOException ex) {
                _logger.error("Error,", ex);
            }
        }
    }
    return LogFileJson.builder().lastKnownPosition(lastKnownPosition).data(logBuilder.toString()).build();
}

From source file:org.stem.db.FatFileAllocator.java

public static void allocateFile(String filePath, long sizeInMB, boolean mark) throws IOException {
    long started = System.currentTimeMillis();

    Closer closer = Closer.create();//  w  w  w .ja  v a2  s. c o m
    try {
        File file = new File(filePath);
        if (file.exists())
            throw new IOException(String.format("File already exists: %s", filePath));

        RandomAccessFile rw = closer.register(new RandomAccessFile(file, "rw"));
        rw.setLength(sizeInMB * 1024 * 1024);
        if (mark) {
            rw.seek(0);
            rw.writeByte(FatFile.MARKER_BLANK);
            rw.seek(rw.length() - 1);
            rw.writeByte(FatFile.MARKER_BLANK);
        }
    } catch (Throwable e) {
        throw closer.rethrow(e);
    } finally {
        closer.close();
        logger.debug("{} was allocated in {} ms", filePath, System.currentTimeMillis() - started);
    }
}

From source file:org.apache.hadoop.hdfs.server.datanode.BlockMetadataHeader.java

/**
 * Read the header at the beginning of the given block meta file.
 * The current file position will be altered by this method.
 * If an error occurs, the file is <em>not</em> closed.
 *//*from ww w. j av a2  s.co  m*/
public static BlockMetadataHeader readHeader(RandomAccessFile raf) throws IOException {
    byte[] buf = new byte[getHeaderSize()];
    raf.seek(0);
    raf.readFully(buf, 0, buf.length);
    return readHeader(new DataInputStream(new ByteArrayInputStream(buf)));
}