unicodefilterwriter.java

这是学习Java必须读懂两套源代码

/*
 * $RCSfile: UnicodeFilterWriter.java,v $
 * $Revision: 1.1.2.2 $
 * $Date: 2001/01/21 19:00:21 $
 *
 * Copyright (C) 2000 CoolServlets.com. All rights reserved.
 *
 * ===================================================================
 * The Apache Software License, Version 1.1
 *
 * 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
 *        CoolServlets.com (http://www.Yasna.com)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Jive" and "CoolServlets.com" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please
 *    contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Jive",
 *    nor may "Jive" appear in their name, without prior written
 *    permission of CoolServlets.com.
 *
 * 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 COOLSERVLETS.COM 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 CoolServlets.com. For more information
 * on CoolServlets.com, please see <http://www.Yasna.com>.
 */

package com.Yasna.util;

import java.io.*;

/**
 * Class for writing non-null unicode characters to character streams.<p>
 *
 * Example use:<p>
 *
 * <code>Writer out = new UnicodeWriter(new FileWriter("blah.txt"));</code>
 */
public class UnicodeFilterWriter extends Writer {

    // Underlying writer
    private Writer out;

    /**
     * Create a new UnicodeWriter
     *
     * @param out A Writer.
     */
    public UnicodeFilterWriter( Writer out ) {
        super(out);
        this.out = out;
    }

    /**
     * Check each character in the character array for the null character. If
     * the null character is found ignore it (don't write to underlying character
     * stream).
     *
     * @param cbuf The character array
     * @param offset Offset from which to start writing characters
     * @param length Number of characters to write
     */
    public void write(char[] cbuf, int offset, int length) throws IOException {
        synchronized( lock ) {
            int loopEnd = (offset+length);
            for( int i=offset; i<loopEnd; i++ ) {
                switch(cbuf[i]) {
                    // null character case
                    case '\u0000':
                        break;
                    case '\u0018':
                        break;
                    // everything else
                    default:
                        out.write(cbuf[i]);
                        break;
                }
            }
        }
    }

    /**
     * Flush the stream
     */
    public void flush() throws IOException {
	    synchronized (lock) {
	        out.flush();
	    }
    }

    /**
     * Close the stream
     */
    public void close() throws IOException {
	    synchronized (lock) {
	        if (out == null) {
		        return;
            }
	        out.close();
    	    out = null;
	    }
    }

}