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 * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
044 * @since 1.4
045 */
046public class Base64OutputStream extends BaseNCodecOutputStream {
047
048    /**
049     * Creates a Base64OutputStream such that all data written is Base64-encoded to the original provided OutputStream.
050     *
051     * @param out
052     *            OutputStream to wrap.
053     */
054    public Base64OutputStream(final OutputStream out) {
055        this(out, true);
056    }
057
058    /**
059     * Creates a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
060     * original provided OutputStream.
061     *
062     * @param out
063     *            OutputStream to wrap.
064     * @param doEncode
065     *            true if we should encode all data written to us, false if we should decode.
066     */
067    public Base64OutputStream(final OutputStream out, final boolean doEncode) {
068        super(out,new Base64(false), doEncode);
069    }
070
071    /**
072     * Creates a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
073     * original provided OutputStream.
074     *
075     * @param out
076     *            OutputStream to wrap.
077     * @param doEncode
078     *            true if we should encode all data written to us, false if we should decode.
079     * @param lineLength
080     *            If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
081     *            nearest multiple of 4). If lineLength &lt;= 0, the encoded data is not divided into lines. If doEncode
082     *            is false, lineLength is ignored.
083     * @param lineSeparator
084     *            If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
085     *            If lineLength &lt;= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
086     */
087    public Base64OutputStream(final OutputStream out, final boolean doEncode,
088                              final int lineLength, final byte[] lineSeparator) {
089        super(out, new Base64(lineLength, lineSeparator), doEncode);
090    }
091}