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/*
* ====================================================================
* 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package ch.boye.httpclientandroidlib.impl.io;
import java.io.IOException;
import java.io.OutputStream;
import ch.boye.httpclientandroidlib.io.SessionOutputBuffer;
/**
* Implements chunked transfer coding. The content is sent in small chunks.
* Entities transferred using this output stream can be of unlimited length.
* Writes are buffered to an internal buffer (2048 default size).
* <p>
* Note that this class NEVER closes the underlying stream, even when close
* gets called. Instead, the stream will be marked as closed and no further
* output will be permitted.
*
*
* @since 4.0
*/
public class ChunkedOutputStream extends OutputStream {
// ----------------------------------------------------- Instance Variables
private final SessionOutputBuffer out;
private byte[] cache;
private int cachePosition = 0;
private boolean wroteLastChunk = false;
/** True if the stream is closed. */
private boolean closed = false;
// ----------------------------------------------------------- Constructors
/**
* Wraps a session output buffer and chunk-encodes the output.
*
* @param out The session output buffer
* @param bufferSize The minimum chunk size (excluding last chunk)
* @throws IOException in case of an I/O error
*/
public ChunkedOutputStream(final SessionOutputBuffer out, int bufferSize)
throws IOException {
super();
this.cache = new byte[bufferSize];
this.out = out;
}
/**
* Wraps a session output buffer and chunks the output. The default buffer
* size of 2048 was chosen because the chunk overhead is less than 0.5%
*
* @param out the output buffer to wrap
* @throws IOException in case of an I/O error
*/
public ChunkedOutputStream(final SessionOutputBuffer out)
throws IOException {
this(out, 2048);
}
// ----------------------------------------------------------- Internal methods
/**
* Writes the cache out onto the underlying stream
*/
protected void flushCache() throws IOException {
if (this.cachePosition > 0) {
this.out.writeLine(Integer.toHexString(this.cachePosition));
this.out.write(this.cache, 0, this.cachePosition);
this.out.writeLine("");
this.cachePosition = 0;
}
}
/**
* Writes the cache and bufferToAppend to the underlying stream
* as one large chunk
*/
protected void flushCacheWithAppend(byte bufferToAppend[], int off, int len) throws IOException {
this.out.writeLine(Integer.toHexString(this.cachePosition + len));
this.out.write(this.cache, 0, this.cachePosition);
this.out.write(bufferToAppend, off, len);
this.out.writeLine("");
this.cachePosition = 0;
}
protected void writeClosingChunk() throws IOException {
// Write the final chunk.
this.out.writeLine("0");
this.out.writeLine("");
}
// ----------------------------------------------------------- Public Methods
/**
* Must be called to ensure the internal cache is flushed and the closing
* chunk is written.
* @throws IOException in case of an I/O error
*/
public void finish() throws IOException {
if (!this.wroteLastChunk) {
flushCache();
writeClosingChunk();
this.wroteLastChunk = true;
}
}
// -------------------------------------------- OutputStream Methods
public void write(int b) throws IOException {
if (this.closed) {
throw new IOException("Attempted write to closed stream.");
}
this.cache[this.cachePosition] = (byte) b;
this.cachePosition++;
if (this.cachePosition == this.cache.length) flushCache();
}
/**
* Writes the array. If the array does not fit within the buffer, it is
* not split, but rather written out as one large chunk.
*/
public void write(byte b[]) throws IOException {
write(b, 0, b.length);
}
/**
* Writes the array. If the array does not fit within the buffer, it is
* not split, but rather written out as one large chunk.
*/
public void write(byte src[], int off, int len) throws IOException {
if (this.closed) {
throw new IOException("Attempted write to closed stream.");
}
if (len >= this.cache.length - this.cachePosition) {
flushCacheWithAppend(src, off, len);
} else {
System.arraycopy(src, off, cache, this.cachePosition, len);
this.cachePosition += len;
}
}
/**
* Flushes the content buffer and the underlying stream.
*/
public void flush() throws IOException {
flushCache();
this.out.flush();
}
/**
* Finishes writing to the underlying stream, but does NOT close the underlying stream.
*/
public void close() throws IOException {
if (!this.closed) {
this.closed = true;
finish();
this.out.flush();
}
}
}
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