Quadcap Embeddable Server

com/quadcap/io/RandomAccessFileInputStream.java

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package com.quadcap.io;

/* Copyright 1997 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.InputStream;
import java.io.IOException;
import java.io.RandomAccessFile;

import com.quadcap.util.Debug;

/**
 * This class implements an input stream filter which keeps track of how
 * many bytes have been read.
 *
 * @author Stan Bailes
 */
public class RandomAccessFileInputStream extends InputStream {
    long                        mark    = -1;
    RandomAccessFile            ra;

    /**
     * Construct a new RandomAccessFileInputStream rearang from the
     * specified file.
     *
     * @param ra the file
     */
    public RandomAccessFileInputStream(RandomAccessFile ra) {
        this.ra = ra;
    }

    /**
     * Read the next byte from this input stream.
     *
     * @exception IOException if an I/O error occurs.
     */
    public int read() throws IOException {
//      Debug.println(0, "read[" + ra.getFilePointer() + "] (" + 1 + ")");
        return ra.read();
    }

    /**
     * Read a block of bytes from this input stream.
     *
     * @exception IOException if an I/O error occcurs.
     */
    public int read(byte[] buf, int offset, int count) throws IOException {
//      Debug.println(0, "read[" + ra.getFilePointer() + "] (" + count + ")");
        return ra.read(buf, offset, count);
    }

    /**
     * Read a block of bytes from this input stream.
     *
     * @exception IOException if an I/O error occcurs.
     */
    public int read(byte[] buf)  throws IOException {
//      Debug.println(0, "read[" + ra.getFilePointer() + "] (" +
//                    buf.length + ")");
        return ra.read(buf);
    }

    /**
     * Return the number of bytes that can be read without blocking.
     */
    public int available() throws IOException {
        return (int)(ra.length() - ra.getFilePointer());
    }

    /**
     * Close the stream.
     */
    public void close() throws IOException {
        ra.close();
    }

    /**
     * Skip ahead in the stream.
     */
    public long skip(long n) throws IOException {
        ra.seek(ra.getFilePointer() + n);
        return n;
    }

    /**
     * Mark the current position in the input stream.
     */
    public void mark(int readLimit) {
        try {
            this.mark = ra.getFilePointer();
        } catch (IOException e) {
            Debug.print(e);
            throw new RuntimeException(e.toString());
        }
    }

    /**
     * Return to the previously marked position in the input stream.
     */
    public void reset() throws IOException {
        if (mark < 0) throw new IOException("no mark");
        ra.seek(mark);
    }

    /**
     * Return true if mark/reset supported (they are.)
     */
    public boolean markSupported() {
        return true;
    }
}