Example usage for java.nio.channels FileChannel map

Introduction

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

Prototype

public abstract MappedByteBuffer map(MapMode mode, long position, long size) throws IOException;

Source Link

Document

Maps a region of this channel's file directly into memory.

Usage

From source file:Main.java

public static void main(String[] argv) throws Exception {
    File file = new File("filename");
    // Create a read-only memory-mapped file
    FileChannel roChannel = new RandomAccessFile(file, "r").getChannel();

    ByteBuffer readonlybuffer = roChannel.map(FileChannel.MapMode.READ_ONLY, 0, (int) roChannel.size());

}

From source file:Main.java

public static void main(String[] argv) throws Exception {
    File file = new File("filename");
    FileChannel channel = new RandomAccessFile(file, "rw").getChannel();
    MappedByteBuffer buf = channel.map(FileChannel.MapMode.READ_WRITE, 0, (int) channel.size());

    buf.put(0, (byte) 0xFF);

    System.out.println(buf.isLoaded());

    buf.force();/*www  . j  a  va  2 s.c  om*/

    channel.close();
}

From source file:Main.java

public static void main(String[] argv) throws Exception {
    File file = new File("filename");
    FileChannel channel = new RandomAccessFile(file, "rw").getChannel();
    MappedByteBuffer buf = channel.map(FileChannel.MapMode.READ_WRITE, 0, (int) channel.size());

    buf.put(0, (byte) 0xFF);

    System.out.println(buf.isLoaded());

    buf.force();/*from ww  w .j ava 2  s.c  om*/

    MappedByteBuffer mbb = buf.load();

    channel.close();
}

From source file:Main.java

public static void main(String[] argv) throws Exception {
    File file = new File("filename");
    FileChannel roChannel = new RandomAccessFile(file, "r").getChannel();
    ByteBuffer readonlybuffer = roChannel.map(FileChannel.MapMode.READ_ONLY, 0, (int) roChannel.size());

    FileChannel rwChannel = new RandomAccessFile(file, "rw").getChannel();
    ByteBuffer writeonlybuffer = rwChannel.map(FileChannel.MapMode.READ_WRITE, 0, (int) rwChannel.size());

    // Create a private (copy-on-write) memory-mapped file.
    FileChannel pvChannel = new RandomAccessFile(file, "rw").getChannel();

    ByteBuffer privatebuffer = roChannel.map(FileChannel.MapMode.READ_WRITE, 0, (int) rwChannel.size());

}

From source file:Main.java

public static void main(String[] args) throws Exception {
    FileInputStream fis = new FileInputStream("test.txt");
    FileChannel fc = fis.getChannel();

    long startRegion = 0;
    long endRegion = fc.size();
    MappedByteBuffer mbb = fc.map(FileChannel.MapMode.READ_ONLY, startRegion, endRegion);
    while (mbb.hasRemaining()) {
        System.out.print((char) mbb.get());
    }//from w ww  . j a  v a2 s .c om
    fis.close();
}

From source file:Main.java

static public void main(String args[]) throws Exception {
    File infile = new File("inFilename");
    File outfile = new File("outFilename");

    RandomAccessFile inraf = new RandomAccessFile(infile, "r");
    RandomAccessFile outraf = new RandomAccessFile(outfile, "rw");

    FileChannel finc = inraf.getChannel();
    FileChannel foutc = outraf.getChannel();

    MappedByteBuffer inmbb = finc.map(FileChannel.MapMode.READ_ONLY, 0, (int) infile.length());

    Charset inCharset = Charset.forName("UTF8");
    Charset outCharset = Charset.forName("UTF16");

    CharsetDecoder inDecoder = inCharset.newDecoder();
    CharsetEncoder outEncoder = outCharset.newEncoder();

    CharBuffer cb = inDecoder.decode(inmbb);
    ByteBuffer outbb = outEncoder.encode(cb);

    foutc.write(outbb);/*from w w w  .  jav  a 2  s . co m*/

    inraf.close();
    outraf.close();
}

From source file:MappedChannelWrite.java

public static void main(String args[]) {
    RandomAccessFile fOut;/*from   ww  w  .ja  va 2s.c om*/
    FileChannel fChan;
    ByteBuffer mBuf;

    try {
        fOut = new RandomAccessFile("test.txt", "rw");
        fChan = fOut.getChannel();
        mBuf = fChan.map(FileChannel.MapMode.READ_WRITE, 0, 26);
        for (int i = 0; i < 26; i++)
            mBuf.put((byte) ('A' + i));

        fChan.close();
        fOut.close();
    } catch (IOException exc) {
        System.out.println(exc);
        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:WordCount.java

public static void main(String args[]) throws Exception {
    String filename = "WordCount.java";

    // Map File from filename to byte buffer
    FileInputStream input = new FileInputStream(filename);
    FileChannel channel = input.getChannel();
    int fileLength = (int) channel.size();
    MappedByteBuffer buffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, fileLength);

    // Convert to character buffer
    Charset charset = Charset.forName("ISO-8859-1");
    CharsetDecoder decoder = charset.newDecoder();
    CharBuffer charBuffer = decoder.decode(buffer);

    // Create line pattern
    Pattern linePattern = Pattern.compile(".*$", Pattern.MULTILINE);

    // Create word pattern
    Pattern wordBreakPattern = Pattern.compile("[\\p{Punct}\\s}]");

    // Match line pattern to buffer
    Matcher lineMatcher = linePattern.matcher(charBuffer);

    Map map = new TreeMap();
    Integer ONE = new Integer(1);

    // For each line
    while (lineMatcher.find()) {
        // Get line
        CharSequence line = lineMatcher.group();

        // Get array of words on line
        String words[] = wordBreakPattern.split(line);

        // For each word
        for (int i = 0, n = words.length; i < n; i++) {
            if (words[i].length() > 0) {
                Integer frequency = (Integer) map.get(words[i]);
                if (frequency == null) {
                    frequency = ONE;//w ww .j av a  2 s .c  o m
                } else {
                    int value = frequency.intValue();
                    frequency = new Integer(value + 1);
                }
                map.put(words[i], frequency);
            }
        }
    }
    System.out.println(map);
}

From source file:MainClass.java

public static void main(String args[]) {
    RandomAccessFile randomAccessFile;
    FileChannel fileChannel;
    ByteBuffer byteBuffer;//from  w ww.  j a  va  2 s .com

    try {
        randomAccessFile = new RandomAccessFile("test.txt", "rw");
        fileChannel = randomAccessFile.getChannel();
        byteBuffer = fileChannel.map(FileChannel.MapMode.READ_WRITE, 0, 26);
        for (int i = 0; i < 10; i++)
            byteBuffer.put((byte) ('A' + i));
        fileChannel.close();
        randomAccessFile.close();
    } catch (IOException exc) {
        System.out.println(exc);
        System.exit(1);
    }
}