checkedoutputstream.java

来自「This is a resource based on j2me embedde」· Java 代码 · 共 88 行

/*
 * @(#)CheckedOutputStream.java	1.22 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * 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 version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package java.util.zip;

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

/**
 * An output stream that also maintains a checksum of the data being
 * written. The checksum can then be used to verify the integrity of
 * the output data.
 *
 * @see		Checksum
 * @version 	1.15, 02/02/00
 * @author 	David Connelly
 */
public
class CheckedOutputStream extends FilterOutputStream {
    private Checksum cksum;

    /**
     * Creates an output stream with the specified Checksum.
     * @param out the output stream
     * @param cksum the checksum
     */
    public CheckedOutputStream(OutputStream out, Checksum cksum) {
	super(out);
	this.cksum = cksum;
    }

    /**
     * Writes a byte. Will block until the byte is actually written.
     * @param b the byte to be written
     * @exception IOException if an I/O error has occurred
     */
    public void write(int b) throws IOException {
	out.write(b);
	cksum.update(b);
    }

    /**
     * Writes an array of bytes. Will block until the bytes are
     * actually written.
     * @param b the data to be written
     * @param off the start offset of the data
     * @param len the number of bytes to be written
     * @exception IOException if an I/O error has occurred
     */
    public void write(byte[] b, int off, int len) throws IOException {
	out.write(b, off, len);
	cksum.update(b, off, len);
    }

    /**
     * Returns the Checksum for this output stream.
     * @return the Checksum
     */
    public Checksum getChecksum() {
	return cksum;
    }
}