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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.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
/**
* An InputStream that does Base64 decoding on the data read through
* it.
*/
public class Base64InputStream extends FilterInputStream {
private final Base64.Coder coder;
private static byte[] EMPTY = new byte[0];
private static final int BUFFER_SIZE = 2048;
private boolean eof;
private byte[] inputBuffer;
private int outputStart;
private int outputEnd;
/**
* An InputStream that performs Base64 decoding on the data read
* from the wrapped stream.
*
* @param in the InputStream to read the source data from
* @param flags bit flags for controlling the decoder; see the
* constants in {@link Base64}
*/
public Base64InputStream(InputStream in, int flags) {
this(in, flags, false);
}
/**
* Performs Base64 encoding or decoding on the data read from the
* wrapped InputStream.
*
* @param in the InputStream to read the source data from
* @param flags bit flags for controlling the decoder; see the
* constants in {@link Base64}
* @param encode true to encode, false to decode
*
* @hide
*/
public Base64InputStream(InputStream in, int flags, boolean encode) {
super(in);
eof = false;
inputBuffer = new byte[BUFFER_SIZE];
if (encode) {
coder = new Base64.Encoder(flags, null);
} else {
coder = new Base64.Decoder(flags, null);
}
coder.output = new byte[coder.maxOutputSize(BUFFER_SIZE)];
outputStart = 0;
outputEnd = 0;
}
public boolean markSupported() {
return false;
}
public void mark(int readlimit) {
throw new UnsupportedOperationException();
}
public void reset() {
throw new UnsupportedOperationException();
}
public void close() throws IOException {
in.close();
inputBuffer = null;
}
public int available() {
return outputEnd - outputStart;
}
public long skip(long n) throws IOException {
if (outputStart >= outputEnd) {
refill();
}
if (outputStart >= outputEnd) {
return 0;
}
long bytes = Math.min(n, outputEnd-outputStart);
outputStart += bytes;
return bytes;
}
public int read() throws IOException {
if (outputStart >= outputEnd) {
refill();
}
if (outputStart >= outputEnd) {
return -1;
} else {
return coder.output[outputStart++] & 0xff;
}
}
public int read(byte[] b, int off, int len) throws IOException {
if (outputStart >= outputEnd) {
refill();
}
if (outputStart >= outputEnd) {
return -1;
}
int bytes = Math.min(len, outputEnd-outputStart);
System.arraycopy(coder.output, outputStart, b, off, bytes);
outputStart += bytes;
return bytes;
}
/**
* Read data from the input stream into inputBuffer, then
* decode/encode it into the empty coder.output, and reset the
* outputStart and outputEnd pointers.
*/
private void refill() throws IOException {
if (eof) return;
int bytesRead = in.read(inputBuffer);
boolean success;
if (bytesRead == -1) {
eof = true;
success = coder.process(EMPTY, 0, 0, true);
} else {
success = coder.process(inputBuffer, 0, bytesRead, false);
}
if (!success) {
throw new Base64DataException("bad base-64");
}
outputEnd = coder.op;
outputStart = 0;
}
}
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