    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one or more
    003 * contributor license agreements.  See the NOTICE file distributed with
    004 * this work for additional information regarding copyright ownership.
    005 * The ASF licenses this file to You under the Apache License, Version 2.0
    006 * (the "License"); you may not use this file except in compliance with
    007 * the License.  You may obtain a copy of the License at
    008 *
    009 *      http://www.apache.org/licenses/LICENSE-2.0
    010 *
    011 * Unless required by applicable law or agreed to in writing, software
    012 * distributed under the License is distributed on an "AS IS" BASIS,
    013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    014 * See the License for the specific language governing permissions and
    015 * limitations under the License.
    016 */
    017
    018package org.apache.commons.codec.binary;
    019
    020import java.io.OutputStream;
    021
    022/**
    023 * Provides Base64 encoding and decoding in a streaming fashion (unlimited size). When encoding the default lineLength
    024 * is 76 characters and the default lineEnding is CRLF, but these can be overridden by using the appropriate
    025 * constructor.
    026 * <p>
    027 * The default behaviour of the Base64OutputStream is to ENCODE, whereas the default behaviour of the Base64InputStream
    028 * is to DECODE. But this behaviour can be overridden by using a different constructor.
    029 * </p>
    030 * <p>
    031 * This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
    032 * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
    033 * </p>
    034 * <p>
    035 * Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
    036 * character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
    037 * </p>
    038 * <p>
    039 * <b>Note:</b> It is mandatory to close the stream after the last byte has been written to it, otherwise the
    040 * final padding will be omitted and the resulting data will be incomplete/inconsistent.
    041 * </p>
    042 *
    043 * @version $Id$
    044 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
    045 * @since 1.4
    046 */
    047public class Base64OutputStream extends BaseNCodecOutputStream {
    048
    049    /**
    050     * Creates a Base64OutputStream such that all data written is Base64-encoded to the original provided OutputStream.
    051     *
    052     * @param out
    053     *            OutputStream to wrap.
    054     */
    055    public Base64OutputStream(final OutputStream out) {
    056        this(out, true);
    057    }
    058
    059    /**
    060     * Creates a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
    061     * original provided OutputStream.
    062     *
    063     * @param out
    064     *            OutputStream to wrap.
    065     * @param doEncode
    066     *            true if we should encode all data written to us, false if we should decode.
    067     */
    068    public Base64OutputStream(final OutputStream out, final boolean doEncode) {
    069        super(out,new Base64(false), doEncode);
    070    }
    071
    072    /**
    073     * Creates a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
    074     * original provided OutputStream.
    075     *
    076     * @param out
    077     *            OutputStream to wrap.
    078     * @param doEncode
    079     *            true if we should encode all data written to us, false if we should decode.
    080     * @param lineLength
    081     *            If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
    082     *            nearest multiple of 4). If lineLength &lt;= 0, the encoded data is not divided into lines. If doEncode
    083     *            is false, lineLength is ignored.
    084     * @param lineSeparator
    085     *            If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
    086     *            If lineLength &lt;= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
    087     */
    088    public Base64OutputStream(final OutputStream out, final boolean doEncode,
    089                              final int lineLength, final byte[] lineSeparator) {
    090        super(out, new Base64(lineLength, lineSeparator), doEncode);
    091    }
    092}