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[]) throws IOException

Source Link

Document

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

Usage

From source file:de.erdesignerng.dialect.msaccess.MSAccessFileFormat.java

private static int findInFile(String aFileName, String aSearchFor) {
    int theBufferSize = 5242880; // 5MB
    boolean theSearchOn = true;
    String theStringBuffer;/* w w  w  . j  a v  a2 s  . c  om*/
    int theOffset = 0;
    int theRead = theBufferSize;
    int thePosition;
    int theOverhead = aSearchFor.length() - 1;
    int theResult = -1;

    if (theBufferSize >= aSearchFor.length()) {
        try {
            File file = new File(aFileName);
            RandomAccessFile ra = new RandomAccessFile(aFileName, "r");
            byte[] theByteBuffer = new byte[theBufferSize];

            while ((theOffset < file.length()) && (theSearchOn) && (theRead == theBufferSize)) {
                theRead = ra.read(theByteBuffer);

                if (theRead >= 0) {
                    theStringBuffer = new String(theByteBuffer, 0, theRead);

                    thePosition = theStringBuffer.indexOf(aSearchFor);

                    if (thePosition >= 0) {
                        theResult = theOffset + thePosition;
                        theSearchOn = false;
                        LOGGER.debug(
                                "Found '" + aSearchFor + "' in '" + aFileName + "' at position " + theResult);
                    } else {
                        if (theRead == theBufferSize) {
                            theOffset += (theRead - theOverhead);
                            ra.seek(theOffset);
                        }
                    }
                }
            }

            ra.close();
        } catch (FileNotFoundException ex) {
            LOGGER.error("Cannot find database file " + aFileName, ex);
        } catch (IOException ex) {
            LOGGER.error("Cannot read database file " + aFileName, ex);
        }
    } else {
        throw new RuntimeException("The string to find is too long. Only strings of lenght up to "
                + theBufferSize + " can be found!");
    }

    return theResult;
}

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   ww  w . j  a va 2 s  .  c  o m*/
        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);
    }

}

From source file:org.mhisoft.common.util.FileUtils.java

public static int readInt(RandomAccessFile fileInputStream) throws IOException {
    byte[] bytesInt = new byte[4];
    int readBytes = fileInputStream.read(bytesInt);
    if (readBytes != 4)
        throw new RuntimeException("didn't read 4 bytes for a integer");

    return ByteArrayHelper.bytesToInt(bytesInt);
}

From source file:jsave.Utils.java

private static BigInteger read_uint64(final RandomAccessFile raf) throws IOException {
    byte[] data = new byte[8];
    raf.read(data);
    return new BigInteger(1, data);
}

From source file:jsave.Utils.java

public static int read_long(final RandomAccessFile raf) throws IOException {
    byte[] data = new byte[4];
    raf.read(data);
    ByteBuffer bb = ByteBuffer.allocate(data.length);
    bb.put(data);/*from   w  w w .ja  v a 2s  .com*/
    return bb.getInt(0);
}

From source file:jsave.Utils.java

public static int read_uint16(final RandomAccessFile raf) throws IOException {
    byte[] data = new byte[2];
    raf.read(data);
    ByteBuffer bb = ByteBuffer.allocate(data.length);
    bb.put(data);//w ww.  j ava  2  s.  c  o  m
    return getUnsignedShort(bb);
}

From source file:jsave.Utils.java

public static long read_uint32(final RandomAccessFile raf) throws IOException {
    byte[] data = new byte[4];
    raf.read(data);
    ByteBuffer bb = ByteBuffer.allocate(data.length);
    bb.put(data);// w  ww. j  av a  2s  .  c o m
    return getUnsignedInt(bb);
}

From source file:jsave.Utils.java

/**
 * Skip length bytes./*  w ww.j a v  a2s.c om*/
 *
 * @param raf the file where the bytes are read
 * @param length the length to skip
 * @throws IOException
 */
public static void skip_bytes(final RandomAccessFile raf, int length) throws IOException {
    byte[] data = new byte[length];
    raf.read(data);
}

From source file:jsave.Utils.java

/**
 * Reads an Integer (-2147483648 to 2147483647).
 *
 * @param raf the 4 Bytes where the file is read
 * @return an Integer/*w ww.j a  va2s.  co m*/
 */
private static int read_int32(RandomAccessFile raf) {
    byte[] data = new byte[4];
    int intData = -1;
    try {
        raf.read(data);
        intData = ByteBuffer.wrap(data).getInt();
    } catch (IOException e) {
    }
    return intData;
}

From source file:jsave.Utils.java

/**
 * Reads a Integer (-9223372036854775808 to 9223372036854775807).
 *
 * @param raf the 4 Bytes where the file is read
 * @return an long integer//from   w w  w. j a v a  2 s . c  om
 */
private static long read_int64(RandomAccessFile raf) {
    byte[] data = new byte[8];
    long intData = -1;
    try {
        raf.read(data);
        intData = ByteBuffer.wrap(data).getLong();
    } catch (IOException e) {
    }
    return intData;
}