/*
* $Header: /home/jerenkrantz/tmp/commons/commons-convert/cvs/home/cvs/jakarta-commons//httpclient/src/java/org/apache/commons/httpclient/ChunkedOutputStream.java,v 1.16 2004/05/13 04:03:25 mbecke Exp $
* $Revision: 480424 $
* $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
*
* ====================================================================
*
* 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 org.apache.commons.httpclient;
import java.io.IOException;
import java.io.OutputStream;
import org.apache.commons.httpclient.util.EncodingUtil;
/**
* Implements HTTP chunking support. Writes are buffered to an internal buffer (2048 default size).
* Chunks are guaranteed to be at least as large as the buffer size (except for the last chunk).
*
* @author Mohammad Rezaei, Goldman, Sachs & Co.
*/
public class ChunkedOutputStream extends OutputStream {
// ------------------------------------------------------- Static Variables
private static final byte CRLF[] = new byte[] {(byte) 13, (byte) 10};
/** End chunk */
private static final byte ENDCHUNK[] = CRLF;
/** 0 */
private static final byte ZERO[] = new byte[] {(byte) '0'};
// ----------------------------------------------------- Instance Variables
private OutputStream stream = null;
private byte[] cache;
private int cachePosition = 0;
private boolean wroteLastChunk = false;
// ----------------------------------------------------------- Constructors
/**
* Wraps a stream and chunks the output.
* @param stream to wrap
* @param bufferSize minimum chunk size (excluding last chunk)
* @throws IOException
*
* @since 3.0
*/
public ChunkedOutputStream(OutputStream stream, int bufferSize) throws IOException {
this.cache = new byte[bufferSize];
this.stream = stream;
}
/**
* Wraps a stream and chunks the output. The default buffer size of 2048 was chosen because
* the chunk overhead is less than 0.5%
* @param stream
* @throws IOException
*/
public ChunkedOutputStream(OutputStream stream) throws IOException {
this(stream, 2048);
}
// ----------------------------------------------------------- Internal methods
/**
* Writes the cache out onto the underlying stream
* @throws IOException
*
* @since 3.0
*/
protected void flushCache() throws IOException {
if (cachePosition > 0) {
byte chunkHeader[] = EncodingUtil.getAsciiBytes(
Integer.toHexString(cachePosition) + "\r\n");
stream.write(chunkHeader, 0, chunkHeader.length);
stream.write(cache, 0, cachePosition);
stream.write(ENDCHUNK, 0, ENDCHUNK.length);
cachePosition = 0;
}
}
/**
* Writes the cache and bufferToAppend to the underlying stream
* as one large chunk
* @param bufferToAppend
* @param off
* @param len
* @throws IOException
*
* @since 3.0
*/
protected void flushCacheWithAppend(byte bufferToAppend[], int off, int len) throws IOException {
byte chunkHeader[] = EncodingUtil.getAsciiBytes(
Integer.toHexString(cachePosition + len) + "\r\n");
stream.write(chunkHeader, 0, chunkHeader.length);
stream.write(cache, 0, cachePosition);
stream.write(bufferToAppend, off, len);
stream.write(ENDCHUNK, 0, ENDCHUNK.length);
cachePosition = 0;
}
protected void writeClosingChunk() throws IOException {
// Write the final chunk.
stream.write(ZERO, 0, ZERO.length);
stream.write(CRLF, 0, CRLF.length);
stream.write(ENDCHUNK, 0, ENDCHUNK.length);
}
// ----------------------------------------------------------- Public Methods
/**
* Must be called to ensure the internal cache is flushed and the closing chunk is written.
* @throws IOException
*
* @since 3.0
*/
public void finish() throws IOException {
if (!wroteLastChunk) {
flushCache();
writeClosingChunk();
wroteLastChunk = true;
}
}
// -------------------------------------------- OutputStream Methods
/**
* Write the specified byte to our output stream.
*
* Note: Avoid this method as it will cause an inefficient single byte chunk.
* Use write (byte[], int, int) instead.
*
* @param b The byte to be written
* @throws IOException if an input/output error occurs
*/
public void write(int b) throws IOException {
cache[cachePosition] = (byte) b;
cachePosition++;
if (cachePosition == 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.
* @param b
* @throws IOException
*
* @since 3.0
*/
public void write(byte b[]) throws IOException {
this.write(b, 0, b.length);
}
public void write(byte src[], int off, int len) throws IOException {
if (len >= cache.length - cachePosition) {
flushCacheWithAppend(src, off, len);
} else {
System.arraycopy(src, off, cache, cachePosition, len);
cachePosition += len;
}
}
/**
* Flushes the underlying stream, but leaves the internal buffer alone.
* @throws IOException
*/
public void flush() throws IOException {
stream.flush();
}
/**
* Finishes writing to the underlying stream, but does NOT close the underlying stream.
* @throws IOException
*/
public void close() throws IOException {
finish();
super.close();
}
}