Java ByteBuffer Size mapByteBuffer(File cachedFile, int cacheFileSize)

Here you can find the source of mapByteBuffer(File cachedFile, int cacheFileSize)

Description

map Byte Buffer

License

Open Source License

Declaration

public static ByteBuffer mapByteBuffer(File cachedFile, int cacheFileSize) throws IOException 

Method Source Code


//package com.java2s;
/*/*from   ww w. ja  va 2 s  .  co m*/
 * Copyright (C) 2010 Stephen Tigner
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

import java.io.*;
import java.nio.ByteBuffer;

import java.nio.channels.FileChannel;

public class Main {
    public static ByteBuffer mapByteBuffer(File cachedFile, int cacheFileSize) throws IOException {
        ByteBuffer byteBufferPositions = null;

        if (cacheFileSize > 1024) // don't cache tiny files
            try {
                if (cachedFile.canRead() && cachedFile.length() == cacheFileSize) {
                    RandomAccessFile raf = new RandomAccessFile(cachedFile, "r");
                    byteBufferPositions = raf.getChannel().map(FileChannel.MapMode.READ_ONLY, 0, cacheFileSize);
                    return byteBufferPositions;
                }

                if (cachedFile.exists())
                    cachedFile.delete();
                cachedFile.getParentFile().mkdirs();
                cachedFile.createNewFile();
                if (cachedFile.canWrite()) {
                    RandomAccessFile raf = new RandomAccessFile(cachedFile, "rw");
                    byteBufferPositions = raf.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, cacheFileSize);
                    return byteBufferPositions;
                }
            } catch (Exception e) {
            }

        byteBufferPositions = ByteBuffer.allocate(cacheFileSize); //int[number_of_statesl];
        return byteBufferPositions;
    }
}

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