Base64OutputStream.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.apache.commons.codec.binary;
import java.io.OutputStream;
import org.apache.commons.codec.CodecPolicy;
/**
* Provides Base64 encoding and decoding in a streaming fashion (unlimited size). When encoding the default lineLength
* is 76 characters and the default lineEnding is CRLF, but these can be overridden by using the appropriate
* constructor.
* <p>
* The default behavior of the Base64OutputStream is to ENCODE, whereas the default behavior of the Base64InputStream
* is to DECODE. But this behavior can be overridden by using a different constructor.
* </p>
* <p>
* This class implements section <cite>6.8. Base64 Content-Transfer-Encoding</cite> from RFC 2045 <cite>Multipurpose
* Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies</cite> by Freed and Borenstein.
* </p>
* <p>
* Since this class operates directly on byte streams, and not character streams, it is hard-coded to only encode/decode
* character encodings which are compatible with the lower 127 ASCII chart (ISO-8859-1, Windows-1252, UTF-8, etc).
* </p>
* <p>
* <b>Note:</b> It is mandatory to close the stream after the last byte has been written to it, otherwise the
* final padding will be omitted and the resulting data will be incomplete/inconsistent.
* </p>
* <p>
* You can set the decoding behavior when the input bytes contain leftover trailing bits that cannot be created by a
* valid encoding. These can be bits that are unused from the final character or entire characters. The default mode is
* lenient decoding.
* </p>
* <ul>
* <li>Lenient: Any trailing bits are composed into 8-bit bytes where possible. The remainder are discarded.
* <li>Strict: The decoding will raise an {@link IllegalArgumentException} if trailing bits are not part of a valid
* encoding. Any unused bits from the final character must be zero. Impossible counts of entire final characters are not
* allowed.
* </ul>
* <p>
* When strict decoding is enabled it is expected that the decoded bytes will be re-encoded to a byte array that matches
* the original, i.e. no changes occur on the final character. This requires that the input bytes use the same padding
* and alphabet as the encoder.
* </p>
* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
* @since 1.4
*/
public class Base64OutputStream extends BaseNCodecOutputStream {
/**
* Constructs a Base64OutputStream such that all data written is Base64-encoded to the original provided OutputStream.
*
* @param outputStream
* OutputStream to wrap.
*/
public Base64OutputStream(final OutputStream outputStream) {
this(outputStream, true);
}
/**
* Constructs a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
* original provided OutputStream.
*
* @param outputStream
* OutputStream to wrap.
* @param doEncode
* true if we should encode all data written to us, false if we should decode.
*/
public Base64OutputStream(final OutputStream outputStream, final boolean doEncode) {
super(outputStream, new Base64(false), doEncode);
}
/**
* Constructs a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
* original provided OutputStream.
*
* @param outputStream
* OutputStream to wrap.
* @param doEncode
* true if we should encode all data written to us, false if we should decode.
* @param lineLength
* If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
* the nearest multiple of 4). If lineLength <= 0, the encoded data is not divided into lines. If
* doEncode is false, lineLength is ignored.
* @param lineSeparator
* If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
* If lineLength <= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
*/
public Base64OutputStream(final OutputStream outputStream, final boolean doEncode, final int lineLength, final byte[] lineSeparator) {
super(outputStream, new Base64(lineLength, lineSeparator), doEncode);
}
/**
* Constructs a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
* original provided OutputStream.
*
* @param outputStream
* OutputStream to wrap.
* @param doEncode
* true if we should encode all data written to us, false if we should decode.
* @param lineLength
* If doEncode is true, each line of encoded data will contain lineLength characters (rounded down to
* the nearest multiple of 4). If lineLength <= 0, the encoded data is not divided into lines. If
* doEncode is false, lineLength is ignored.
* @param lineSeparator
* If doEncode is true, each line of encoded data will be terminated with this byte sequence (e.g. \r\n).
* If lineLength <= 0, the lineSeparator is not used. If doEncode is false lineSeparator is ignored.
* @param decodingPolicy The decoding policy.
* @since 1.15
*/
public Base64OutputStream(final OutputStream outputStream, final boolean doEncode, final int lineLength, final byte[] lineSeparator,
final CodecPolicy decodingPolicy) {
super(outputStream, new Base64(lineLength, lineSeparator, false, decodingPolicy), doEncode);
}
}