svn-gvsig-desktop / branches / Mobile_Compatible_Hito_1 / libFMap_mobile_shp_driver / src-comp / org / gvsig / datasources / impljme / BufferedBigByteBufferJME.java @ 21927
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package org.gvsig.datasources.impljme; |
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import java.io.IOException; |
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import java.nio.ByteOrder; |
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import org.apache.log4j.Logger; |
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import org.gvsig.datasources.common.IBigByteBuffer; |
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import org.gvsig.datasources.common.IByteBuffer; |
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import org.gvsig.datasources.common.IRandomFileChannel; |
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/**
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* This class implements the IBigByteBuffer for JME. As the desktop version,
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* it keeps a small buffer in memory, by using the classes ByteBufferJME
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* and RandomFileChannelJME.
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*
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* @see org.gvsig.datasources.impljme.ByteBufferJME
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* @see org.gvsig.datasources.impljme.RandomFileChannelJME
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*
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* @author jldominguez
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*
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*/
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public class BufferedBigByteBufferJME implements IBigByteBuffer { |
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private static Logger logger = Logger.getLogger(BufferedBigByteBufferJME.class); |
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/**
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* Memory buffer size
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*/
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public static long DEFAULT_SIZE = 4*1024; // 8 Kbytes |
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private ByteBufferJME theBuffer = null; |
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private RandomFileChannelJME fc;
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private long minAbs, maxAbs, posAbs; |
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private int minRel, maxRel, posRel; |
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private long sizeChunk, amountMem; |
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private long fileSize; |
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private int mode; |
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public BufferedBigByteBufferJME(IRandomFileChannel ch, int acc_mode) { |
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amountMem = DEFAULT_SIZE; |
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fc = (RandomFileChannelJME) ch; |
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try {
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fileSize = fc.size(); |
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mode = acc_mode; |
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sizeChunk = Math.min(fc.size(), amountMem);
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} catch (IOException e) { |
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logger.error("While instantiating: " + e.getMessage());
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} |
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theBuffer = (ByteBufferJME) Impl.allocateDirect((int) sizeChunk);
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byte[] aux = new byte[(int) sizeChunk]; |
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fc.getAsIs(aux); |
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theBuffer.put(aux); |
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theBuffer.position(0);
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minAbs = 0;
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maxAbs = sizeChunk; |
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} |
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/**
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* Checks the position and loads the data if necessary.
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*
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* @throws IOException
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*/
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private void prepareBuffer(long posActual, int numBytesToRead) |
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{ |
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long desiredPos = posActual + numBytesToRead;
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if ((desiredPos > maxAbs) || (posActual < minAbs)) {
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// logger.debug("Se ha pedido fuera del buffer: Tenemos: ["
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// + minAbs + " , " + maxAbs + "], Se pide hasta: " + desiredPos);
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// Quiero leer fuera:
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sizeChunk = Math.min(fileSize-posActual, amountMem);
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try {
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mapFrom(posActual); |
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} catch (IOException e) { |
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e.printStackTrace(); |
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} |
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} else {
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theBuffer.position((int) (posActual - minAbs));
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// System.out.println("NOT setting in buffer");
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} |
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// Dejamos posAbs apuntando a donde va a quedar
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// "a priori", antes de leer de verdad, que se hace
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// al salir de esta funci?n.
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posAbs = desiredPos; |
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} |
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/**
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* @param posActual
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* @throws IOException
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*/
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private IByteBuffer mapFrom(long newPos) throws IOException { |
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ByteOrder lastOrder = theBuffer.order();
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// bb = fc.map(mode, newPos, sizeChunk);
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fc.position((int) newPos);
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// bb = ByteBuffer.wrap(buff);
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// bb = ByteBuffer.allocate((int)sizeChunk);
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theBuffer.position(0);
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byte[] newbuf = new byte[(int) sizeChunk]; |
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fc.getAsIs(newbuf); |
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theBuffer = new ByteBufferJME(newbuf);
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// System.out.println("Mapeo desde " + newPos + " con sizeChunk= " + sizeChunk + " numRead = " + numRead);
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minAbs = newPos; |
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maxAbs = sizeChunk + newPos; |
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theBuffer.order(lastOrder); |
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return theBuffer;
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} |
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public void position(long p) { |
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prepareBuffer(p, 0);
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int relPos = (int) (p - minAbs); |
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if (relPos < 0) { |
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System.out.println("Position=" + p); |
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} |
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} |
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public int position() { |
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// TODO Auto-generated method stub
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return (int) posAbs; |
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} |
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public byte get() { |
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prepareBuffer(posAbs, 1);
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return theBuffer.get();
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} |
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public byte getByte(int ind) { |
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prepareBuffer(ind, 1);
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return theBuffer.get(ind - (int) minAbs); |
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} |
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public int getInt() { |
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prepareBuffer(posAbs, 4);
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return theBuffer.getInt();
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} |
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public short getShort() { |
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prepareBuffer(posAbs, 2);
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return theBuffer.getShort();
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} |
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public int getInt(int index) { |
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prepareBuffer(index, 4);
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return theBuffer.getInt(index - (int) minAbs); |
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} |
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public void get(byte[] out) { |
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prepareBuffer(posAbs, out.length); |
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theBuffer.get(out); |
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} |
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public double getDouble() { |
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prepareBuffer(posAbs, 8);
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return theBuffer.getDouble();
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} |
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public void order(ByteOrder o) { |
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theBuffer.order(o); |
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} |
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} |