Example usage for java.io RandomAccessFile read

Introduction

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

Prototype

public int read(byte b[], int off, int len) throws IOException 

Source Link

Document

Reads up to len bytes of data from this file into an array of bytes.

Usage

From source file:Main.java

public static void main(String[] args) {
    try {/*from w w w. j  ava 2s  .  com*/
        byte[] b1 = { 1, 2, 3 };
        byte[] b2 = { 1, 2, 3, 4, 5, 6, 7, 8 };

        RandomAccessFile raf = new RandomAccessFile("c:/test.txt", "rw");

        // write something in the file
        raf.writeUTF("Hello World from java2s.com");

        // set the file pointer at 0 position
        raf.seek(0);

        // read 2 bytes, starting from 1
        System.out.println(raf.read(b1, 1, 2));

        // set the file pointer at 0 position
        raf.seek(0);

        // read 3 bytes, starting from 4rth
        System.out.println(raf.read(b2, 4, 3));
        raf.close();
    } catch (IOException ex) {
        ex.printStackTrace();
    }

}

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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  v  a 2  s . com*/
    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();
}

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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;
        }//from  w  w w. jav a 2s . c o 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:org.jcodec.common.io.Buffer.java

private static int read(byte[] buffer, int pos, int size, RandomAccessFile is) throws IOException {
    int read, total = 0;

    while (size > 0 && (read = is.read(buffer, pos, size)) != -1) {
        pos += read;//from  w  w  w  .  ja va  2s.  c o  m
        size -= read;
        total += read;
    }

    return total;
}

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From source file:org.piwigo.remotesync.api.util.FileUtil.java

/**
 * chunkNumber start at 0//from w  ww  .  j a  v  a2s . c  o m
 */
public static byte[] getFilePart(File file, int chunkSize, int chunkNumber) {
    RandomAccessFile randomAccessFile = null;
    try {
        randomAccessFile = new RandomAccessFile(file, "r");
        int bytesSize = getChunkSize(file, chunkSize, chunkNumber);
        byte[] bytes = new byte[bytesSize];
        randomAccessFile.seek(chunkSize * chunkNumber);
        randomAccessFile.read(bytes, 0, bytesSize);
        return bytes;
    } catch (IOException e) {
        throw new IORuntimeException("Cannot get file part", e);
    } finally {
        IOUtils.closeQuietly(randomAccessFile);
    }
}

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From source file:com.haulmont.cuba.core.sys.logging.LogArchiver.java

private static byte[] getTailBytes(File logFile) throws FileNotFoundException {
    ByteArrayOutputStream bos = new ByteArrayOutputStream();

    byte[] buf = null;
    int len;//ww  w .ja va  2  s . c  om
    int size = 1024;
    try {
        RandomAccessFile randomAccessFile = new RandomAccessFile(logFile, "r");
        long lengthFile = randomAccessFile.length();
        if (lengthFile >= LOG_TAIL_FOR_PACKING_SIZE) {
            randomAccessFile.seek(lengthFile - LOG_TAIL_FOR_PACKING_SIZE);
        }
        buf = new byte[size];
        while ((len = randomAccessFile.read(buf, 0, size)) != -1) {
            bos.write(buf, 0, len);
        }
        buf = bos.toByteArray();
    } catch (IOException e) {
        log.error("Unable to get tail for log file " + logFile.getName(), e);
    } finally {
        IOUtils.closeQuietly(bos);
    }
    return buf;
}

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From source file:com.aoyetech.fee.commons.utils.FileUtils.java

public static String getFileContent(final File tFile)
        throws IOException, FileNotFoundException, UnsupportedEncodingException {
    if (!tFile.isFile()) {
        throw new IOException("?");
    }//from ww w . j  av a2  s .co  m
    final RandomAccessFile file = new RandomAccessFile(tFile, "r");
    final long fileSize = file.length();
    final byte[] bytes = new byte[(int) fileSize];
    long readLength = 0L;
    while (readLength < fileSize) {
        final int onceLength = file.read(bytes, (int) readLength, (int) (fileSize - readLength));
        if (onceLength > 0) {
            readLength += onceLength;
        } else {
            break;
        }
    }

    IOUtils.closeQuietly(file);
    return new String(bytes, Constants.ENCODE);
}

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From source file:org.broadinstitute.gatk.utils.io.IOUtils.java

/**
 * Determines the uncompressed size of a GZIP file. Uses the GZIP ISIZE field in the last
 * 4 bytes of the file to get this information.
 *
 * @param gzipFile GZIP-format file whose uncompressed size to determine
 * @return The uncompressed size (in bytes) of the GZIP file
 *//*from   w  w  w  .  j  a  v a2s.  com*/
public static int getGZIPFileUncompressedSize(File gzipFile) {
    if (gzipFile == null) {
        throw new ReviewedGATKException("GZIP file to examine was null");
    }

    try {
        // The GZIP ISIZE field holds the uncompressed size of the compressed data.
        // It occupies the last 4 bytes of any GZIP file:
        RandomAccessFile in = new RandomAccessFile(gzipFile, "r");
        in.seek(gzipFile.length() - 4);
        byte[] sizeBytes = new byte[4];
        in.read(sizeBytes, 0, 4);

        ByteBuffer byteBuf = ByteBuffer.wrap(sizeBytes);
        byteBuf.order(ByteOrder.LITTLE_ENDIAN); // The GZIP spec mandates little-endian byte order
        int uncompressedSize = byteBuf.getInt();

        // If the size read in is negative, we've overflowed our signed integer:
        if (uncompressedSize < 0) {
            throw new UserException.CouldNotReadInputFile(String.format(
                    "Cannot accurately determine the uncompressed size of file %s "
                            + "because it's either larger than %d bytes or the GZIP ISIZE field is corrupt",
                    gzipFile.getAbsolutePath(), Integer.MAX_VALUE));
        }

        return uncompressedSize;
    } catch (IOException e) {
        throw new UserException.CouldNotReadInputFile(gzipFile, e);
    }
}

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From source file:org.broadinstitute.sting.utils.io.IOUtils.java

/**
 * Determines the uncompressed size of a GZIP file. Uses the GZIP ISIZE field in the last
 * 4 bytes of the file to get this information.
 *
 * @param gzipFile GZIP-format file whose uncompressed size to determine
 * @return The uncompressed size (in bytes) of the GZIP file
 *///from w  w  w  .  j  a  v a2 s .com
public static int getGZIPFileUncompressedSize(File gzipFile) {
    if (gzipFile == null) {
        throw new ReviewedStingException("GZIP file to examine was null");
    }

    try {
        // The GZIP ISIZE field holds the uncompressed size of the compressed data.
        // It occupies the last 4 bytes of any GZIP file:
        RandomAccessFile in = new RandomAccessFile(gzipFile, "r");
        in.seek(gzipFile.length() - 4);
        byte[] sizeBytes = new byte[4];
        in.read(sizeBytes, 0, 4);

        ByteBuffer byteBuf = ByteBuffer.wrap(sizeBytes);
        byteBuf.order(ByteOrder.LITTLE_ENDIAN); // The GZIP spec mandates little-endian byte order
        int uncompressedSize = byteBuf.getInt();

        // If the size read in is negative, we've overflowed our signed integer:
        if (uncompressedSize < 0) {
            throw new UserException.CouldNotReadInputFile(String.format(
                    "Cannot accurately determine the uncompressed size of file %s "
                            + "because it's either larger than %d bytes or the GZIP ISIZE field is corrupt",
                    gzipFile.getAbsolutePath(), Integer.MAX_VALUE));
        }

        return uncompressedSize;
    } catch (IOException e) {
        throw new UserException.CouldNotReadInputFile(gzipFile, e);
    }
}

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From source file:au.org.ala.layers.grid.GridCacheBuilder.java

static void nextRowOfFloats(float[] row, String datatype, boolean byteOrderLSB, int ncols, RandomAccessFile raf,
        byte[] b, float noDataValue) throws IOException {
    int size = 4;
    if (datatype.charAt(0) == 'U') {
        size = 1;//from  w  w  w. ja  v a  2 s. c  o m
    } else if (datatype.charAt(0) == 'B') {
        size = 1;
    } else if (datatype.charAt(0) == 'S') {
        size = 2;
    } else if (datatype.charAt(0) == 'I') {
        size = 4;
    } else if (datatype.charAt(0) == 'L') {
        size = 8;
    } else if (datatype.charAt(0) == 'F') {
        size = 4;
    } else if (datatype.charAt(0) == 'D') {
        size = 8;
    }

    raf.read(b, 0, size * ncols);
    ByteBuffer bb = ByteBuffer.wrap(b);
    if (byteOrderLSB) {
        bb.order(ByteOrder.LITTLE_ENDIAN);
    } else {
        bb.order(ByteOrder.BIG_ENDIAN);
    }

    int i;
    int length = ncols;
    if (datatype.charAt(0) == 'U') {
        for (i = 0; i < length; i++) {
            float ret = bb.get();
            if (ret < 0) {
                ret += 256;
            }
            row[i] = ret;
        }
    } else if (datatype.charAt(0) == 'B') {

        for (i = 0; i < length; i++) {
            row[i] = (float) bb.get();
        }
    } else if (datatype.charAt(0) == 'S') {
        for (i = 0; i < length; i++) {
            row[i] = (float) bb.getShort();
        }
    } else if (datatype.charAt(0) == 'I') {
        for (i = 0; i < length; i++) {
            row[i] = (float) bb.getInt();
        }
    } else if (datatype.charAt(0) == 'L') {
        for (i = 0; i < length; i++) {
            row[i] = (float) bb.getLong();
        }
    } else if (datatype.charAt(0) == 'F') {
        for (i = 0; i < length; i++) {
            row[i] = (float) bb.getFloat();
        }
    } else if (datatype.charAt(0) == 'D') {
        for (i = 0; i < length; i++) {
            row[i] = (float) bb.getDouble();
        }
    } else {
        logger.info("UNKNOWN TYPE: " + datatype);
    }

    for (i = 0; i < length; i++) {
        if (row[i] == noDataValue) {
            row[i] = Float.NaN;
        }
    }
}

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