checkedoutputstream.java

来自「《移动Agent技术》一书的所有章节源代码。」· Java 代码 · 共 82 行

/*
 * @(#)CheckedOutputStream.java	1.9 96/11/23
 * 
 * Copyright (c) 1995, 1996 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the confidential and proprietary information of Sun
 * Microsystems, Inc. ("Confidential Information").  You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Sun.
 * 
 * SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF THE
 * SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
 * PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR ANY DAMAGES
 * SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR DISTRIBUTING
 * THIS SOFTWARE OR ITS DERIVATIVES.
 * 
 * CopyrightVersion 1.1_beta
 * 
 */

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 	1.9, 11/23/96
 * @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 buf 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.
     */
    public Checksum getChecksum() {
	return cksum;
    }
}