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    
018    package org.apache.commons.codec.binary;
019    
020    import java.io.InputStream;
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 Base64InputStream is to DECODE, whereas the default behaviour of the Base64OutputStream
028     * is to ENCODE, 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     * 
039     * @author Apache Software Foundation 
040     * @version $Id: Base64InputStream.java 1064424 2011-01-28 02:02:46Z sebb $
041     * @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
042     * @since 1.4
043     */
044    public class Base64InputStream extends BaseNCodecInputStream {
045    
046        /**
047         * Creates a Base64InputStream such that all data read is Base64-decoded from the original provided InputStream.
048         * 
049         * @param in
050         *            InputStream to wrap.
051         */
052        public Base64InputStream(InputStream in) {
053            this(in, false);
054        }
055    
056        /**
057         * Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original
058         * provided InputStream.
059         * 
060         * @param in
061         *            InputStream to wrap.
062         * @param doEncode
063         *            true if we should encode all data read from us, false if we should decode.
064         */
065        public Base64InputStream(InputStream in, boolean doEncode) {
066            super(in, new Base64(false), doEncode);
067        }
068    
069        /**
070         * Creates a Base64InputStream such that all data read is either Base64-encoded or Base64-decoded from the original
071         * provided InputStream.
072         * 
073         * @param in
074         *            InputStream to wrap.
075         * @param doEncode
076         *            true if we should encode all data read from us, false if we should decode.
077         * @param lineLength
078         *            If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
079         *            nearest multiple of 4). If lineLength <=0, the encoded data is not divided into lines. If doEncode is
080         *            false, lineLength is ignored.
081         * @param lineSeparator
082         *            If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
083         *            If lineLength <= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
084         */
085        public Base64InputStream(InputStream in, boolean doEncode, int lineLength, byte[] lineSeparator) {
086            super(in, new Base64(lineLength, lineSeparator), doEncode);
087        }
088    }