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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
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 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
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 * This software consists of voluntary contributions made by many
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package org.apache.http.impl.io;

import java.io.IOException;
import java.io.OutputStream;

import org.apache.http.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).
 * 

* 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 final byte[] cache; private int cachePosition = 0; private boolean wroteLastChunk = false; /** True if the stream is closed. */ private boolean closed = false; /** * 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 not thrown * * @deprecated (4.3) use {@link ChunkedOutputStream#ChunkedOutputStream(int, SessionOutputBuffer)} */ @Deprecated public ChunkedOutputStream(final SessionOutputBuffer out, final int bufferSize) throws IOException { this(bufferSize, 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 not thrown * * @deprecated (4.3) use {@link ChunkedOutputStream#ChunkedOutputStream(int, SessionOutputBuffer)} */ @Deprecated public ChunkedOutputStream(final SessionOutputBuffer out) throws IOException { this(2048, out); } /** * Wraps a session output buffer and chunk-encodes the output. * * @param bufferSize The minimum chunk size (excluding last chunk) * @param out The session output buffer */ public ChunkedOutputStream(final int bufferSize, final SessionOutputBuffer out) { super(); this.cache = new byte[bufferSize]; this.out = out; } /** * 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(final byte bufferToAppend[], final int off, final 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 @Override public void write(final 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. */ @Override public void write(final 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. */ @Override public void write(final byte src[], final int off, final 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. */ @Override public void flush() throws IOException { flushCache(); this.out.flush(); } /** * Finishes writing to the underlying stream, but does NOT close the underlying stream. */ @Override public void close() throws IOException { if (!this.closed) { this.closed = true; finish(); this.out.flush(); } } }





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