/*
* 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.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* 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 behaviour of the Base64OutputStream is to ENCODE, whereas the default behaviour of the Base64InputStream
* is to DECODE. But this behaviour 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>
*
* @author Apache Software Foundation
* @version $Id: Base64OutputStream.java 799806 2009-08-01 04:33:17Z ggregory $
* @see <a href="http://www.ietf.org/rfc/rfc2045.txt">RFC 2045</a>
* @since 1.4
*/
public class Base64OutputStream extends FilterOutputStream {
private final boolean doEncode;
private final Base64 base64;
private final byte[] singleByte = new byte[1];
/**
* Creates a Base64OutputStream such that all data written is Base64-encoded to the original provided OutputStream.
*
* @param out
* OutputStream to wrap.
*/
public Base64OutputStream(OutputStream out) {
this(out, true);
}
/**
* Creates a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
* original provided OutputStream.
*
* @param out
* OutputStream to wrap.
* @param doEncode
* true if we should encode all data written to us, false if we should decode.
*/
public Base64OutputStream(OutputStream out, boolean doEncode) {
super(out);
this.doEncode = doEncode;
this.base64 = new Base64();
}
/**
* Creates a Base64OutputStream such that all data written is either Base64-encoded or Base64-decoded to the
* original provided OutputStream.
*
* @param out
* 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
* 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(OutputStream out, boolean doEncode, int lineLength, byte[] lineSeparator) {
super(out);
this.doEncode = doEncode;
this.base64 = new Base64(lineLength, lineSeparator);
}
/**
* Writes the specified <code>byte</code> to this output stream.
*
* @param i
* source byte
* @throws IOException
* if an I/O error occurs.
*/
public void write(int i) throws IOException {
singleByte[0] = (byte) i;
write(singleByte, 0, 1);
}
/**
* Writes <code>len</code> bytes from the specified <code>b</code> array starting at <code>offset</code> to this
* output stream.
*
* @param b
* source byte array
* @param offset
* where to start reading the bytes
* @param len
* maximum number of bytes to write
*
* @throws IOException
* if an I/O error occurs.
* @throws NullPointerException
* if the byte array parameter is null
* @throws IndexOutOfBoundsException
* if offset, len or buffer size are invalid
*/
public void write(byte b[], int offset, int len) throws IOException {
if (b == null) {
throw new NullPointerException();
} else if (offset < 0 || len < 0) {
throw new IndexOutOfBoundsException();
} else if (offset > b.length || offset + len > b.length) {
throw new IndexOutOfBoundsException();
} else if (len > 0) {
if (doEncode) {
base64.encode(b, offset, len);
} else {
base64.decode(b, offset, len);
}
flush(false);
}
}
/**
* Flushes this output stream and forces any buffered output bytes to be written out to the stream. If propogate is
* true, the wrapped stream will also be flushed.
*
* @param propogate
* boolean flag to indicate whether the wrapped OutputStream should also be flushed.
* @throws IOException
* if an I/O error occurs.
*/
private void flush(boolean propogate) throws IOException {
int avail = base64.avail();
if (avail > 0) {
byte[] buf = new byte[avail];
int c = base64.readResults(buf, 0, avail);
if (c > 0) {
out.write(buf, 0, c);
}
}
if (propogate) {
out.flush();
}
}
/**
* Flushes this output stream and forces any buffered output bytes to be written out to the stream.
*
* @throws IOException
* if an I/O error occurs.
*/
public void flush() throws IOException {
flush(true);
}
/**
* Closes this output stream and releases any system resources associated with the stream.
*
* @throws IOException
* if an I/O error occurs.
*/
public void close() throws IOException {
// Notify encoder of EOF (-1).
if (doEncode) {
base64.encode(singleByte, 0, -1);
} else {
base64.decode(singleByte, 0, -1);
}
flush();
out.close();
}
}