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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed 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 android.util;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
* An OutputStream that does Base64 encoding on the data written to
* it, writing the resulting data to another OutputStream.
*/
public class Base64OutputStream extends FilterOutputStream {
private final Base64.Coder coder;
private final int flags;
private byte[] buffer = null;
private int bpos = 0;
private static byte[] EMPTY = new byte[0];
/**
* Performs Base64 encoding on the data written to the stream,
* writing the encoded data to another OutputStream.
*
* @param out the OutputStream to write the encoded data to
* @param flags bit flags for controlling the encoder; see the
* constants in {@link Base64}
*/
public Base64OutputStream(OutputStream out, int flags) {
this(out, flags, true);
}
/**
* Performs Base64 encoding or decoding on the data written to the
* stream, writing the encoded/decoded data to another
* OutputStream.
*
* @param out the OutputStream to write the encoded data to
* @param flags bit flags for controlling the encoder; see the
* constants in {@link Base64}
* @param encode true to encode, false to decode
*
* @hide
*/
public Base64OutputStream(OutputStream out, int flags, boolean encode) {
super(out);
this.flags = flags;
if (encode) {
coder = new Base64.Encoder(flags, null);
} else {
coder = new Base64.Decoder(flags, null);
}
}
public void write(int b) throws IOException {
// To avoid invoking the encoder/decoder routines for single
// bytes, we buffer up calls to write(int) in an internal
// byte array to transform them into writes of decently-sized
// arrays.
if (buffer == null) {
buffer = new byte[1024];
}
if (bpos >= buffer.length) {
// internal buffer full; write it out.
internalWrite(buffer, 0, bpos, false);
bpos = 0;
}
buffer[bpos++] = (byte) b;
}
/**
* Flush any buffered data from calls to write(int). Needed
* before doing a write(byte[], int, int) or a close().
*/
private void flushBuffer() throws IOException {
if (bpos > 0) {
internalWrite(buffer, 0, bpos, false);
bpos = 0;
}
}
public void write(byte[] b, int off, int len) throws IOException {
if (len <= 0) return;
flushBuffer();
internalWrite(b, off, len, false);
}
public void close() throws IOException {
IOException thrown = null;
try {
flushBuffer();
internalWrite(EMPTY, 0, 0, true);
} catch (IOException e) {
thrown = e;
}
try {
if ((flags & Base64.NO_CLOSE) == 0) {
out.close();
} else {
out.flush();
}
} catch (IOException e) {
if (thrown != null) {
thrown = e;
}
}
if (thrown != null) {
throw thrown;
}
}
/**
* Write the given bytes to the encoder/decoder.
*
* @param finish true if this is the last batch of input, to cause
* encoder/decoder state to be finalized.
*/
private void internalWrite(byte[] b, int off, int len, boolean finish) throws IOException {
coder.output = embiggen(coder.output, coder.maxOutputSize(len));
if (!coder.process(b, off, len, finish)) {
throw new Base64DataException("bad base-64");
}
out.write(coder.output, 0, coder.op);
}
/**
* If b.length is at least len, return b. Otherwise return a new
* byte array of length len.
*/
private byte[] embiggen(byte[] b, int len) {
if (b == null || b.length < len) {
return new byte[len];
} else {
return b;
}
}
}
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