CRLFFilterOutputStream.java

/**
 * Copyright 1999-2009 The Pegadi Team
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.pegadi.publisher.io;

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

/**
 * This is a filtered output stream that converts line separators from
 * <CODE>UNIX</CODE>/<CODE>MAC</CODE>
 * into <code>UNIX</CODE>/<CODE>MAC</CODE>/<CODE>WINDOWS</CODE>
 * The line separators are as follows:
 * <ul>
 * <item><code>WINDOWS</code>: <code>CRLF</code> </item>
 * <item><code>MAC</code>: <code>CR</code> </item>
 * <item><code>UNIX</code>: <code>LF</code> </item>
 * </ul>
 */
public class CRLFFilterOutputStream extends FilterOutputStream {

    public enum Mode {WINDOWS, UNIX, MAC, NOFILTER}

    public Mode mode;

    private transient int previous = -1;
    /**
     * Constructor taking a Writer and a mode as arguments
     * @param mode One of <code>UNIX</code>, <code>WINDOWS</code>,
     * <code>MAC</code>
     */
    public CRLFFilterOutputStream(OutputStream out, Mode mode) {
        super(out);
        this.mode=mode;
    }


    /**
     * Writes a single byte while filtering it according to mode
     */
    @Override
    public void write(int b) throws IOException {
        boolean isCRLF = previous == 13 && b == 10;
        boolean isCRCR = previous == 13 && b == 13;
        if(previous == 13){

            if(mode == Mode.WINDOWS){
                if(isCRLF){
                    out.write(13);
                    out.write(10);
                    previous = 10;
                }if(isCRCR){
                    out.write(13);
                    out.write(10);
                    out.write(13);
                    out.write(10);
                    previous = 10;
                }
            }else if(mode == Mode.MAC){
                 if(isCRLF){
                     out.write(10);
                     previous = 10;
                 }else if(isCRCR){
                     out.write(10);
                     out.write(10);
                     previous = 10;
                 }else{
                     out.write(10);
                     out.write(b);
                     previous = b;
                 }
            }else if(mode == Mode.UNIX){
                 if(isCRLF){
                     out.write(13);
                     previous = 13;
                 }else if(isCRCR){
                      out.write(13);
                      out.write(13);
                     previous = 13;
                 }else {
                     out.write(b);
                     previous = b;
                 }
            }
        }else if(b == 13){
            previous = 13;
        }else if(b == 10) {
            if(mode == Mode.WINDOWS){
                out.write(13);
                out.write(10);
                previous = 10;
            } else if(mode == Mode.MAC){
                out.write(10);
                previous = 10;
            } else if(mode == Mode.UNIX){
               out.write(13);
                previous = 13;
            }
        }else {
            out.write(b);
        }
    }

    /**
     * Writes an array of bytes while filtering it according to mode
     */
    @Override
    public void write(byte[] b, int off, int len) throws IOException {

        for(int i=off;i<off+len;i++) {
            write(b[i]);
        }
    }

    /**
     * Writes an array of bytes while filtering it according to mode
     */
    @Override
    public void write(byte[] b) throws IOException {

        for(int i=0;i<b.length;i++) {
            write(b[i]);
        }
    }

}