/* * 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 com.fsck.k9.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. *
* 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. *
* This class implements section 6.8. Base64 Content-Transfer-Encoding from RFC 2045 Multipurpose * Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies by Freed and Borenstein. *
* * @author Apache Software Foundation * @version $Id $ * @see RFC 2045 * @since 1.0-dev */ 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. * 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 specifiedbyte
to this output stream.
*/
public void write(int i) throws IOException {
singleByte[0] = (byte) i;
write(singleByte, 0, 1);
}
/**
* Writes len
bytes from the specified
* b
array starting at offset
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 || offset + 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, flushing any remaining bytes that must be encoded. The
* underlying stream is flushed but not closed.
*/
public void close() throws IOException {
// Notify encoder of EOF (-1).
if (doEncode) {
base64.encode(singleByte, 0, -1);
} else {
base64.decode(singleByte, 0, -1);
}
flush();
}
}