Application: gvSIG desktop

/*

 * Created on 11-jul-2005

 *

 * gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana

 * 

 * Copyright (C) 2004 IVER T.I. and Generalitat Valenciana.

 * 

 * 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.

 *  

 * For more information, contact:

 *

 *  Generalitat Valenciana

 *   Conselleria d'Infraestructures i Transport

 *   Av. Blasco Ib??ez, 50

 *   46010 VALENCIA

 *   SPAIN

 *

 *      +34 963862235

 *   gvsig@gva.es

 *      www.gvsig.gva.es

 * 

 *    or

 * 

 *   IVER T.I. S.A

 *   Salamanca 50

 *   46005 Valencia

 *   Spain

 * 

 *   +34 963163400

 *   dac@iver.es

 */

package com.iver.utiles.bigfile;

import java.io.IOException;

import java.nio.Buffer;

import java.nio.ByteBuffer;

import java.nio.ByteOrder;

import java.nio.CharBuffer;

import java.nio.DoubleBuffer;

import java.nio.FloatBuffer;

import java.nio.IntBuffer;

import java.nio.LongBuffer;

import java.nio.MappedByteBuffer;

import java.nio.ShortBuffer;

import java.nio.channels.FileChannel;

/**

 * @author Fjp

 *

 * Clase para trabajar con ficheros grandes. Mapea solo un trozo

 * de fichero en memoria, y cuando intentas acceder fuera de esa

 * zona, se ocupa de leer autom?ticamente el trozo que le falta.

 */

public class BigByteBuffer {

    private static long DEFAULT_SIZE = 50*1024*1024; // 50 Megas m?ximo

    MappedByteBuffer bb;

    FileChannel fc;

    long minAbs, maxAbs, posAbs;

    int minRel,  maxRel, posRel;

    long sizeChunk, amountMem;

    long fileSize;

    FileChannel.MapMode mode;

    /**

     * Revisa la posici?n absoluta, y si hace falta, carga el buffer

     * con la parte de fichero que toca.

     * @throws IOException 

     */

    private void prepareBuffer(long posActual, int numBytesToRead) 

    {

        long desiredPos = posActual + numBytesToRead;

        if ((desiredPos > maxAbs) || (posActual < minAbs))

        {

            // Quiero leer fuera:

            sizeChunk = Math.min(fileSize-posActual, amountMem);

            try {

                ByteOrder lastOrder = bb.order();

                bb = fc.map(mode, posActual, sizeChunk);

                minAbs = posActual;

                maxAbs = sizeChunk + posActual;

                bb.order(lastOrder);

                // System.out.println("BigByteBuffer: min=" + minAbs 

                //     + " maxAbs=" + maxAbs + " posAbs = " + posAbs);

            } catch (IOException e) {

                // TODO Auto-generated catch block

                e.printStackTrace();

            }

        }

        // Dejamos posAbs apuntando a donde va a quedar

        // "a priori", antes de leer de verdad, que se hace

        // al salir de esta funci?n.

        posAbs = desiredPos;

    }

    public BigByteBuffer(FileChannel fc, FileChannel.MapMode mode, long amountMem) throws IOException

    {

        this.amountMem = amountMem;

        this.fc = fc;

        this.fileSize = fc.size();

        this.mode = mode;

        sizeChunk = Math.min(fc.size(), amountMem);

        bb = fc.map(mode, 0L, sizeChunk);

        minAbs = 0;

        maxAbs = sizeChunk;

    }

    public BigByteBuffer(FileChannel fc, FileChannel.MapMode mode) throws IOException

    {

        this.amountMem = DEFAULT_SIZE;

        this.fc = fc;

        this.fileSize = fc.size();

        this.mode = mode;

        sizeChunk = Math.min(fc.size(), amountMem);

        bb = fc.map(mode, 0L, sizeChunk);

        minAbs = 0;

        maxAbs = sizeChunk;

    }

    public synchronized byte get() {

        prepareBuffer(posAbs,1);

        return bb.get();

    }

    public synchronized ByteBuffer get(byte[] dst)

    {

        prepareBuffer(posAbs, dst.length);

        return bb.get(dst);

    }

    public synchronized char getChar() {

        prepareBuffer(posAbs,2);

        return bb.getChar();

    }

    public synchronized double getDouble() {

        prepareBuffer(posAbs,8);

        return bb.getDouble();

    }

    public synchronized float getFloat() {

        prepareBuffer(posAbs,4);

        return bb.getFloat();

    }

    public synchronized int getInt() {

        prepareBuffer(posAbs,4);

        return bb.getInt();

    }

    public synchronized long getLong() {

        prepareBuffer(posAbs,8);

        return bb.getLong();

    }

    public synchronized short getShort() {

        prepareBuffer(posAbs,2);

        return bb.getShort();

    }

    public boolean isDirect() {

        return bb.isDirect();

    }

    public synchronized byte get(int index) {

        prepareBuffer(index,1);

        return bb.get(index - (int) minAbs);

    }

    public synchronized char getChar(int index) {

        prepareBuffer(index,2);

        return bb.getChar(index - (int) minAbs);

    }

    public synchronized double getDouble(int index) {

        prepareBuffer(index,8);

        return bb.getDouble(index - (int) minAbs);

    }

    public synchronized float getFloat(int index) {

        prepareBuffer(index,4);

        return bb.getFloat(index - (int) minAbs);

    }

    public synchronized int getInt(int index) {

        prepareBuffer(index,4);

        return bb.getInt(index - (int) minAbs);

    }

    public synchronized long getLong(int index) {

        prepareBuffer(index,8);

        return bb.getLong(index - (int) minAbs);

    }

    public synchronized short getShort(int index) {

        prepareBuffer(index,2);

        return bb.getShort(index - (int) minAbs);

    }

    public ByteBuffer asReadOnlyBuffer() { 

        return bb.asReadOnlyBuffer();

    }

    public ByteBuffer compact() {

        return bb.compact();

    }

    public ByteBuffer duplicate() {

        return bb.duplicate();

    }

    public ByteBuffer slice() {

        return bb.slice();

    }

    public synchronized ByteBuffer put(byte b) {

        prepareBuffer(posAbs,1);

        return bb.put(b);

    }

    public synchronized ByteBuffer putChar(char value) {

        prepareBuffer(posAbs,2);

        return bb.putChar(value);

    }

    public synchronized ByteBuffer putDouble(double value) {

        prepareBuffer(posAbs,8);

        return bb.putDouble(value);

    }

    public synchronized ByteBuffer putFloat(float value) {

        prepareBuffer(posAbs,4);

        return bb.putFloat(value);

    }

    public synchronized ByteBuffer putInt(int value) {

        prepareBuffer(posAbs,4);

        return bb.putInt(value);

    }

    public synchronized ByteBuffer put(int index, byte b) {

        prepareBuffer(index,1);

        return bb.put(index- (int) minAbs, b);

    }

    public synchronized ByteBuffer putChar(int index, char value) {

        prepareBuffer(index,2);

        return bb.putChar(index- (int) minAbs, value);

    }

    public synchronized ByteBuffer putDouble(int index, double value) {

        prepareBuffer(index,8);

        return bb.putDouble(index- (int) minAbs, value);

    }

    public synchronized ByteBuffer putFloat(int index, float value) {

        prepareBuffer(index,4);

        return bb.putFloat(index- (int) minAbs, value);

    }

    public synchronized ByteBuffer putInt(int index, int value) {

        prepareBuffer(index,4);

        return bb.putInt(index- (int) minAbs, value);

    }

    public synchronized ByteBuffer putLong(int index, long value) {

        prepareBuffer(index,8);

        return bb.putLong(index- (int) minAbs, value);

    }

    public synchronized ByteBuffer putShort(int index, short value) {

        prepareBuffer(index,2);

        return bb.putShort(index- (int) minAbs, value);

    }

    public synchronized ByteBuffer putLong(long value) {

        prepareBuffer(posAbs,8);

        return bb.putLong(value);

    }

    public synchronized ByteBuffer putShort(short value) {

        prepareBuffer(posAbs,2);

        return bb.putShort(value);

    }

    public CharBuffer asCharBuffer() {

        return bb.asCharBuffer();

    }

    public DoubleBuffer asDoubleBuffer() {

        return bb.asDoubleBuffer();

    }

    public FloatBuffer asFloatBuffer() {

        return bb.asFloatBuffer();

    }

    public IntBuffer asIntBuffer() {

        return bb.asIntBuffer();

    }

    public LongBuffer asLongBuffer() {

        return bb.asLongBuffer();

    }

    public ShortBuffer asShortBuffer() {

        return bb.asShortBuffer();

    }

    public boolean isReadOnly() {

        return bb.isReadOnly();

    }

    public final ByteOrder order()

    {

        return bb.order();

    }

    public final ByteBuffer order(ByteOrder bo)

    {

        return bb.order(bo);

    }

    public final long position()

    {

        return posAbs;

    }

    public synchronized final Buffer position(long newPosition)

    {

        prepareBuffer(newPosition,0);

        int relPos = (int) (newPosition - minAbs);

        // System.out.println("Position=" + newPosition);

        return bb.position(relPos);

    }

}