diff options
Diffstat (limited to 'core/java/android/util/base64/Base64InputStream.java')
-rw-r--r-- | core/java/android/util/base64/Base64InputStream.java | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/core/java/android/util/base64/Base64InputStream.java b/core/java/android/util/base64/Base64InputStream.java new file mode 100644 index 0000000..c0c1636 --- /dev/null +++ b/core/java/android/util/base64/Base64InputStream.java @@ -0,0 +1,169 @@ +/* + * 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.base64; + +import java.io.FilterInputStream; +import java.io.IOException; +import java.io.InputStream; + +/** + * An OutputStream that does either Base64 encoding or decoding on the + * data written to it, writing the resulting data to another + * OutputStream. + */ +public class Base64InputStream extends FilterInputStream { + private final boolean encode; + private final Base64.EncoderState estate; + private final Base64.DecoderState dstate; + + private static byte[] EMPTY = new byte[0]; + + private static final int BUFFER_SIZE = 2048; + private boolean eof; + private byte[] inputBuffer; + private byte[] outputBuffer; + 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 + */ + public Base64InputStream(InputStream in, int flags, boolean encode) { + super(in); + this.encode = encode; + eof = false; + inputBuffer = new byte[BUFFER_SIZE]; + if (encode) { + // len*8/5+10 is an overestimate of the most bytes the + // encoder can produce for len bytes of input. + outputBuffer = new byte[BUFFER_SIZE * 8/5 + 10]; + estate = new Base64.EncoderState(flags, outputBuffer); + dstate = null; + } else { + // len*3/4+10 is an overestimate of the most bytes the + // decoder can produce for len bytes of input. + outputBuffer = new byte[BUFFER_SIZE * 3/4 + 10]; + estate = null; + dstate = new Base64.DecoderState(flags, outputBuffer); + } + 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 outputBuffer[outputStart++]; + } + } + + 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(outputBuffer, outputStart, b, off, bytes); + outputStart += bytes; + return bytes; + } + + /** + * Read data from the input stream into inputBuffer, then + * decode/encode it into the empty outputBuffer, and reset the + * outputStart and outputEnd pointers. + */ + private void refill() throws IOException { + if (eof) return; + int bytesRead = in.read(inputBuffer); + if (encode) { + if (bytesRead == -1) { + eof = true; + Base64.encodeInternal(EMPTY, 0, 0, estate, true); + } else { + Base64.encodeInternal(inputBuffer, 0, bytesRead, estate, false); + } + outputEnd = estate.op; + } else { + if (bytesRead == -1) { + eof = true; + Base64.decodeInternal(EMPTY, 0, 0, dstate, true); + } else { + Base64.decodeInternal(inputBuffer, 0, bytesRead, dstate, false); + } + outputEnd = dstate.op; + } + outputStart = 0; + } +} |