Example usage for java.nio.channels FileChannel size

List of usage examples for java.nio.channels FileChannel size

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Introduction

In this page you can find the example usage for java.nio.channels FileChannel size.

Prototype

public abstract long size() throws IOException;

Source Link

Document

Returns the current size of this channel's file.

Usage

From source file:MainClass.java

public static void main(String args[]) {
    FileInputStream fileInputStream;
    FileChannel fileChannel;
    long fileSize;
    MappedByteBuffer mBuf;//from   www .  j  a  v a2  s  . c o m

    try {
        fileInputStream = new FileInputStream("test.txt");
        fileChannel = fileInputStream.getChannel();
        fileSize = fileChannel.size();
        mBuf = fileChannel.map(FileChannel.MapMode.READ_ONLY, 0, fileSize);

        for (int i = 0; i < fileSize; i++)
            System.out.print((char) mBuf.get());

        fileChannel.close();
        fileInputStream.close();
    } catch (IOException exc) {
        System.out.println(exc);
        System.exit(1);
    }
}

From source file:MainClass.java

public static void main(String[] args) throws Exception {
    File aFile = new File("C:/test.bin");
    RandomAccessFile ioFile = new RandomAccessFile(aFile, " rw");

    FileChannel ioChannel = ioFile.getChannel();
    final int PRIMESREQUIRED = 10;
    long[] primes = new long[PRIMESREQUIRED];

    int index = 0;
    final long REPLACEMENT = 999999L;

    final int PRIMECOUNT = (int) ioChannel.size() / 8;
    MappedByteBuffer buf = ioChannel.map(FileChannel.MapMode.READ_WRITE, 0L, ioChannel.size()).load();
    ioChannel.close();//from   w ww  .ja  va  2s  .  c  o  m

    for (int i = 0; i < PRIMESREQUIRED; i++) {
        index = 8 * (int) (PRIMECOUNT * Math.random());
        primes[i] = buf.getLong(index);
        buf.putLong(index, REPLACEMENT);
    }

    for (long prime : primes) {
        System.out.printf("%12d", prime);
    }
    ioFile.close();
}

From source file:NIOCopy.java

public static void main(String args[]) throws Exception {
    FileInputStream fIn;// w  w  w. j a va  2s. com
    FileOutputStream fOut;
    FileChannel fIChan, fOChan;
    long fSize;
    MappedByteBuffer mBuf;

    fIn = new FileInputStream(args[0]);
    fOut = new FileOutputStream(args[1]);

    fIChan = fIn.getChannel();
    fOChan = fOut.getChannel();
    fSize = fIChan.size();

    mBuf = fIChan.map(FileChannel.MapMode.READ_ONLY, 0, fSize);
    fOChan.write(mBuf); // this copies the file
    fIChan.close();
    fIn.close();

    fOChan.close();
    fOut.close();
}

From source file:GetChannel.java

public static void main(String[] args) throws Exception {
    // Write a file:
    FileChannel fc = new FileOutputStream("data.txt").getChannel();
    fc.write(ByteBuffer.wrap("Some text ".getBytes()));
    fc.close();/* w  w w .  j a v a2  s.c  om*/
    // Add to the end of the file:
    fc = new RandomAccessFile("data.txt", "rw").getChannel();
    fc.position(fc.size()); // Move to the end
    fc.write(ByteBuffer.wrap("Some more".getBytes()));
    fc.close();
    // Read the file:
    fc = new FileInputStream("data.txt").getChannel();
    ByteBuffer buff = ByteBuffer.allocate(BSIZE);
    fc.read(buff);
    buff.flip();
    while (buff.hasRemaining())
        System.out.print((char) buff.get());
}

From source file:MainClass.java

public static void main(String args[]) {
    FileInputStream fIn;//  w ww  .j a v  a2 s . co  m
    FileOutputStream fOut;
    FileChannel fIChan, fOChan;
    long fSize;
    MappedByteBuffer mBuf;

    try {
        fIn = new FileInputStream(args[0]);
        fOut = new FileOutputStream(args[1]);

        fIChan = fIn.getChannel();
        fOChan = fOut.getChannel();

        fSize = fIChan.size();

        mBuf = fIChan.map(FileChannel.MapMode.READ_ONLY, 0, fSize);

        fOChan.write(mBuf); // this copies the file

        fIChan.close();
        fIn.close();

        fOChan.close();
        fOut.close();
    } catch (IOException exc) {
        System.out.println(exc);
        System.exit(1);
    } catch (ArrayIndexOutOfBoundsException exc) {
        System.out.println("Usage: Copy from to");
        System.exit(1);
    }
}

From source file:Main.java

public static void main(String[] argv) throws Exception {
    FileChannel rwChannel = new RandomAccessFile(new File("test.txt"), "rw").getChannel();
    FileChannel roChannel = new RandomAccessFile(new File("test.txt"), "r").getChannel();

    FileChannel pvChannel = new RandomAccessFile(new File("text.txt"), "rw").getChannel();
    ByteBuffer pvBuf = roChannel.map(FileChannel.MapMode.READ_WRITE, 0, (int) rwChannel.size());
}

From source file:Copy.java

public static void main(String[] args) {
    FileChannel in = null;
    FileChannel out = null;/* w w w.j  av a2s  .  co  m*/

    if (args.length < 2) {
        System.out.println("Usage: java Copy <from> <to>");
        System.exit(1);
    }

    try {
        in = new FileInputStream(args[0]).getChannel();
        out = new FileOutputStream(args[1]).getChannel();
        out.transferFrom(in, 0L, (int) in.size());

    } catch (Exception e) {
        e.printStackTrace();
    }
}

From source file:MainClass.java

public static void main(String[] args) throws Exception {
    createFile();/*from   www .  ja v a  2  s.  c  o m*/

    File aFile = new File("C:/primes.bin");
    FileInputStream inFile = new FileInputStream(aFile);

    FileChannel inChannel = inFile.getChannel();

    final int PRIMESREQUIRED = 10;
    ByteBuffer buf = ByteBuffer.allocate(8 * PRIMESREQUIRED);

    long[] primes = new long[PRIMESREQUIRED];
    int index = 0; // Position for a prime in the file

    // Count of primes in the file
    final int PRIMECOUNT = (int) inChannel.size() / 8;

    // Read the number of random primes required
    for (int i = 0; i < PRIMESREQUIRED; i++) {
        index = 8 * (int) (PRIMECOUNT * Math.random());
        inChannel.read(buf, index); // Read the value
        buf.flip();
        primes[i] = buf.getLong(); // Save it in the array
        buf.clear();
    }

    for (long prime : primes) {
        System.out.printf("%12d", prime);
    }
    inFile.close(); // Close the file and the channel

}

From source file:BGrep.java

public static void main(String[] args) {
    String encodingName = "UTF-8"; // Default to UTF-8 encoding
    int flags = Pattern.MULTILINE; // Default regexp flags

    try { // Fatal exceptions are handled after this try block
        // First, process any options
        int nextarg = 0;
        while (args[nextarg].charAt(0) == '-') {
            String option = args[nextarg++];
            if (option.equals("-e")) {
                encodingName = args[nextarg++];
            } else if (option.equals("-i")) { // case-insensitive matching
                flags |= Pattern.CASE_INSENSITIVE;
            } else if (option.equals("-s")) { // Strict Unicode processing
                flags |= Pattern.UNICODE_CASE; // case-insensitive Unicode
                flags |= Pattern.CANON_EQ; // canonicalize Unicode
            } else {
                System.err.println("Unknown option: " + option);
                usage();//  w w w  .  j a va 2s  . c  o m
            }
        }

        // Get the Charset for converting bytes to chars
        Charset charset = Charset.forName(encodingName);

        // Next argument must be a regexp. Compile it to a Pattern object
        Pattern pattern = Pattern.compile(args[nextarg++], flags);

        // Require that at least one file is specified
        if (nextarg == args.length)
            usage();

        // Loop through each of the specified filenames
        while (nextarg < args.length) {
            String filename = args[nextarg++];
            CharBuffer chars; // This will hold complete text of the file
            try { // Handle per-file errors locally
                // Open a FileChannel to the named file
                FileInputStream stream = new FileInputStream(filename);
                FileChannel f = stream.getChannel();

                // Memory-map the file into one big ByteBuffer. This is
                // easy but may be somewhat inefficient for short files.
                ByteBuffer bytes = f.map(FileChannel.MapMode.READ_ONLY, 0, f.size());

                // We can close the file once it is is mapped into memory.
                // Closing the stream closes the channel, too.
                stream.close();

                // Decode the entire ByteBuffer into one big CharBuffer
                chars = charset.decode(bytes);
            } catch (IOException e) { // File not found or other problem
                System.err.println(e); // Print error message
                continue; // and move on to the next file
            }

            // This is the basic regexp loop for finding all matches in a
            // CharSequence. Note that CharBuffer implements CharSequence.
            // A Matcher holds state for a given Pattern and text.
            Matcher matcher = pattern.matcher(chars);
            while (matcher.find()) { // While there are more matches
                // Print out details of the match
                System.out.println(filename + ":" + // file name
                        matcher.start() + ": " + // character pos
                        matcher.group()); // matching text
            }
        }
    }
    // These are the things that can go wrong in the code above
    catch (UnsupportedCharsetException e) { // Bad encoding name
        System.err.println("Unknown encoding: " + encodingName);
    } catch (PatternSyntaxException e) { // Bad pattern
        System.err.println("Syntax error in search pattern:\n" + e.getMessage());
    } catch (ArrayIndexOutOfBoundsException e) { // Wrong number of arguments
        usage();
    }
}

From source file:MainClass.java

public static void main(String[] args) {
    long[] primes = new long[] { 1, 2, 3, 5, 7 };
    File aFile = new File("C:/test/primes.bin");
    FileOutputStream outputFile = null;
    try {/*from   ww  w  . j ava  2  s  . c om*/
        outputFile = new FileOutputStream(aFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace(System.err);
    }
    FileChannel file = outputFile.getChannel();
    final int BUFFERSIZE = 100;
    ByteBuffer buf = ByteBuffer.allocate(BUFFERSIZE);
    LongBuffer longBuf = buf.asLongBuffer();
    int primesWritten = 0;
    while (primesWritten < primes.length) {
        longBuf.put(primes, primesWritten, min(longBuf.capacity(), primes.length - primesWritten));
        buf.limit(8 * longBuf.position());
        try {
            file.write(buf);
            primesWritten += longBuf.position();
        } catch (IOException e) {
            e.printStackTrace(System.err);
        }
        longBuf.clear();
        buf.clear();
    }
    try {
        System.out.println("File written is " + file.size() + "bytes.");
        outputFile.close();
    } catch (IOException e) {
        e.printStackTrace(System.err);
    }
}