Example usage for java.io RandomAccessFile seek

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:com.netflix.imfutility.itunes.image.ImageValidator.java

private static boolean checkBytes(File file, byte[] start, byte[] end) throws IOException {
    RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r");

    byte[] destStart = new byte[start.length];
    if (start.length != 0) {
        int res = randomAccessFile.read(destStart, 0, start.length);
        if (res == -1) {
            return false;
        }/* ww  w.j  av  a2s .  co m*/
    }

    byte[] destEnd = new byte[end.length];
    if (end.length != 0) {
        randomAccessFile.seek(file.length() - end.length);
        int res = randomAccessFile.read(destEnd, 0, end.length);
        if (res == -1) {
            return false;
        }
    }

    return Arrays.equals(start, destStart) && Arrays.equals(end, destEnd);
}

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From source file:fm.last.commons.io.LastFileUtils.java

/**
 * Reads the last bytes from the end of the passed file as a String.
 * //from  w  w  w  . j av a 2s .c o  m
 * @param file File to read from.
 * @param bytes Number of bytes from end of file to read.
 * @return The end content of the file as a String.
 * @throws IOException If the file could not be opened or read.
 */
public static String tail(File file, long bytes) throws IOException {
    RandomAccessFile raFile = null;
    StringBuffer tail = new StringBuffer();
    try {
        raFile = new RandomAccessFile(file, "r");
        long length = raFile.length();
        if (bytes >= length) {
            return FileUtils.readFileToString(file);
        } else {
            raFile.seek(length - bytes);
            tail = new StringBuffer((int) bytes);
            String line = raFile.readLine();
            while (line != null) {
                tail.append(line);
                line = raFile.readLine();
                if (line != null) { // there is another line coming, so add line break
                    tail.append("\n");
                }
            }
        }
    } finally {
        LastIoUtils.closeQuietly(raFile);
    }
    return tail.toString();
}

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From source file:org.fusesource.meshkeeper.util.internal.FileSupport.java

static public byte[] read(File file, long pos, int length) throws IOException {
    RandomAccessFile is = new RandomAccessFile(file, "r");
    try {//from www . ja  v a2  s  . c  o  m
        long remaining = is.length() - pos;
        if (remaining < 0) {
            remaining = 0;
        }
        byte rc[] = new byte[(int) Math.min(remaining, length)];
        if (rc.length == 0) {
            return rc;
        }
        is.seek(pos);
        is.readFully(rc);
        return rc;
    } finally {
        is.close();
    }
}

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From source file:net.sourceforge.doddle_owl.data.JpnWordNetDic.java

private static Concept getConcept(long dfp) {
    RandomAccessFile dataFile = null;
    try {/*from   ww  w.  ja  v a 2 s  . c  o  m*/
        dataFile = jpnwnConceptDataFile;
        dataFile.seek(dfp);
        String data = new String(dataFile.readLine().getBytes("ISO8859_1"), "UTF-8");
        // System.out.println(data);
        String[] dataArray = data.split("\\^");
        String[] conceptData = new String[4];
        String id = dataArray[0].replaceAll("\t", "");
        System.arraycopy(dataArray, 1, conceptData, 0, conceptData.length);

        String uri = "";
        Concept c = null;
        uri = DODDLEConstants.JPN_WN_URI + id;
        c = new Concept(uri, conceptData);
        jpnwnURIConceptMap.put(uri, c);

        return c;
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
    return null;
}

---

From source file:net.sourceforge.doddle_owl.data.JpnWordNetDic.java

private static long getIndexFp(long fp) {
    RandomAccessFile indexFpListFile = null;
    indexFpListFile = jpnwnWordIndexFile;

    try {/*from   w  ww  . j  a v  a 2s .c o  m*/
        indexFpListFile.seek(fp);
        String fpStr = indexFpListFile.readLine();
        if (fpStr == null) {
            return -1;
        }
        return Long.valueOf(fpStr);
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
    return -1;
}

---

From source file:net.sourceforge.doddle_owl.data.JpnWordNetDic.java

private static String getData(long dfp, RandomAccessFile dataFile, String encoding) {
    try {/* w  w  w .  ja  va  2 s .  c o m*/
        // System.out.println("dfp: " + dfp);
        dataFile.seek(dfp);
        return new String(dataFile.readLine().getBytes("ISO8859_1"), encoding);
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
    return null;
}

---

From source file:net.sourceforge.doddle_owl.data.JpnWordNetDic.java

private static String getTermAndIndexFpSet(long ifp) {
    RandomAccessFile indexFile = null;
    indexFile = jpnwnWordDataFile;/* ww  w  . j  a v  a  2s .c  o  m*/

    try {
        // System.out.println("ifp: " + ifp);
        indexFile.seek(ifp);
        return new String(indexFile.readLine().getBytes("ISO8859_1"), "UTF-8");
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }
    return null;
}

---

From source file:com.aol.advertising.qiao.util.CommonUtils.java

public static long checksum(RandomAccessFile raFile, int numBytes)
        throws IOException, InsufficientFileLengthException {
    CRC32 _crc = new CRC32();

    long pos = raFile.getFilePointer();
    try {//from  w w  w .  j  a  v  a  2  s.c  om
        byte[] buffer = new byte[numBytes];
        raFile.seek(0);
        int n = raFile.read(buffer);
        if (n < numBytes) {
            String s;
            logger.warn(s = ("not enough data for checksum: current file size=" + n));
            throw new InsufficientFileLengthException(s);
        }

        synchronized (_crc) {
            _crc.reset();
            _crc.update(buffer);

            return _crc.getValue();
        }
    } finally {
        raFile.seek(pos);
    }

}

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

/**
 * Calculate the md5sum of an image after zeroing out the transaction ID
 * field in the header. This is useful for tests that want to verify
 * that two checkpoints have identical namespaces.
 *//*  ww w  .j a v  a  2s.c  om*/
public static String getImageFileMD5IgnoringTxId(File imageFile) throws IOException {
    File tmpFile = File.createTempFile("hadoop_imagefile_tmp", "fsimage");
    tmpFile.deleteOnExit();
    try {
        Files.copy(imageFile, tmpFile);
        RandomAccessFile raf = new RandomAccessFile(tmpFile, "rw");
        try {
            raf.seek(IMAGE_TXID_POS);
            raf.writeLong(0);
        } finally {
            IOUtils.closeStream(raf);
        }
        return getFileMD5(tmpFile);
    } finally {
        tmpFile.delete();
    }
}

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From source file:Main.java

public static double getCpuUsage1() {
    try {/*from w ww.ja v  a 2  s.c om*/
        RandomAccessFile reader = new RandomAccessFile("/proc/stat", "r");
        String load = reader.readLine();
        String[] toks = load.split(" ");

        double user1 = Double.parseDouble(toks[2]);
        double system1 = Double.parseDouble(toks[4]);
        double irq1 = Double.parseDouble(toks[7]);
        double idle1 = Double.parseDouble(toks[5]);
        try {
            Thread.sleep(360);
        } catch (Exception e) {
            e.printStackTrace();
        }
        reader.seek(0);
        load = reader.readLine();
        reader.close();
        toks = load.split(" ");
        double user2 = Double.parseDouble(toks[2]);
        double system2 = Double.parseDouble(toks[4]);
        double irq2 = Double.parseDouble(toks[7]);
        double idle2 = Double.parseDouble(toks[5]);

        double user_pass = user2 - user1;
        double system_pass = system2 - system1;
        double irq_pass = irq2 - irq1;
        double idle_pass = idle2 - idle1;
        double usage = (user_pass + system_pass + irq_pass) * 100.00
                / (user_pass + irq_pass + system_pass + idle_pass);
        BigDecimal b = new BigDecimal(usage);
        double res = b.setScale(2, BigDecimal.ROUND_HALF_UP).doubleValue();
        return res;
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e1) {
        e1.printStackTrace();
    }

    return 0;

}

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