countingoutputstream.java

jxta_src_2.41b jxta 2.41b 最新版源码 from www.jxta.org

/*
 * Copyright (c) 2001 Sun Microsystems, Inc.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:
 *       "This product includes software developed by the
 *       Sun Microsystems, Inc. for Project JXTA."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact Project JXTA at http://www.jxta.org.
 *
 * 5. Products derived from this software may not be called "JXTA",
 *    nor may "JXTA" appear in their name, without prior written
 *    permission of Sun.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of Project JXTA.  For more
 * information on Project JXTA, please see
 * <http://www.jxta.org/>.
 *
 * This license is based on the BSD license adopted by the Apache Foundation.
 *
 * $Id: CountingOutputStream.java,v 1.2 2003/01/17 18:49:52 bondolo Exp $
 */

package net.jxta.util;

import java.io.OutputStream;
import java.io.IOException;

/**
 *  A filter output stream which counts the bytes sent to the stream. A filter
 *  so that you don't have to count seperately from writing to the output
 *
 **/
public class CountingOutputStream extends java.io.FilterOutputStream {
    
    /**
     *  For recursion detection to prevent overcounting.
     **/
    private transient boolean alreadycounting;
    
    /**
     *  number of bytes which have been written on this stream
     **/
    private long bytesWritten;
    
    /**
     * Creates a new instance of CountingOutputStream
     **/
    public CountingOutputStream( OutputStream out ) {
        super( out );
        bytesWritten = 0;
        alreadycounting = false;
    }
    
    /**
     * {@inheritDoc}
     *
     *  <p/>Debugging toString.
     **/
    public String toString() {
        if( null == out ) {
            return "closed/" + super.toString();
        } else {
            return out.toString() + "/" + super.toString();
        }
    }
    
    /**
     * {@inheritDoc}
     *
     * <p/>Merely calls the super version.
     **/
    public synchronized void write(int b) throws IOException {
        boolean wascounting = alreadycounting;
        alreadycounting = true;
        super.write( b );
        alreadycounting = wascounting;
        if( !alreadycounting )
            bytesWritten++;
    }
    
    /**
     * {@inheritDoc}
     *
     * <p/>calls the super version of the same method.
     **/
    public synchronized void write(byte[] b, int off, int len) throws IOException {
        boolean wascounting = alreadycounting;
        alreadycounting = true;
        super.write( b, off, len );
        alreadycounting = wascounting;
        if( !alreadycounting )
            bytesWritten += len;
    }
    
    /**
     *  Returns the number of bytes written to the stream thus far. This and all
     *  the methods in this class are synchronized because bytesWritten cannot be
     *  volatile.
     *
     *  @return long containing the number of bytes written.
     **/
    public synchronized long getBytesWritten() {
        return bytesWritten;
    }
}