/hudson-core/src/main/java/hudson/util/ChunkedOutputStream.java

  1/*
  2 * $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 $
  3 * $Revision: 480424 $
  4 * $Date: 2006-11-29 06:56:49 +0100 (Wed, 29 Nov 2006) $
  5 *
  6 * ====================================================================
  7 *
  8 *  Licensed to the Apache Software Foundation (ASF) under one or more
  9 *  contributor license agreements.  See the NOTICE file distributed with
 10 *  this work for additional information regarding copyright ownership.
 11 *  The ASF licenses this file to You under the Apache License, Version 2.0
 12 *  (the "License"); you may not use this file except in compliance with
 13 *  the License.  You may obtain a copy of the License at
 14 *
 15 *      http://www.apache.org/licenses/LICENSE-2.0
 16 *
 17 *  Unless required by applicable law or agreed to in writing, software
 18 *  distributed under the License is distributed on an "AS IS" BASIS,
 19 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 20 *  See the License for the specific language governing permissions and
 21 *  limitations under the License.
 22 * ====================================================================
 23 *
 24 * This software consists of voluntary contributions made by many
 25 * individuals on behalf of the Apache Software Foundation.  For more
 26 * information on the Apache Software Foundation, please see
 27 * <http://www.apache.org/>.
 28 *
 29 */
 30
 31package hudson.util;
 32
 33import java.io.IOException;
 34import java.io.OutputStream;
 35
 36/**
 37 * Implements HTTP chunking support. Writes are buffered to an internal buffer (2048 default size).
 38 * Chunks are guaranteed to be at least as large as the buffer size (except for the last chunk).
 39 *
 40 * @author Mohammad Rezaei, Goldman, Sachs & Co.
 41 */
 42public class ChunkedOutputStream extends OutputStream {
 43
 44    // ------------------------------------------------------- Static Variables
 45    private static final byte CRLF[] = new byte[] {(byte) 13, (byte) 10};
 46
 47    /** End chunk */
 48    private static final byte ENDCHUNK[] = CRLF;
 49
 50    /** 0 */
 51    private static final byte ZERO[] = new byte[] {(byte) '0'};
 52
 53    // ----------------------------------------------------- Instance Variables
 54    private OutputStream stream = null;
 55
 56    private byte[] cache;
 57
 58    private int cachePosition = 0;
 59
 60    private boolean wroteLastChunk = false;
 61
 62    // ----------------------------------------------------------- Constructors
 63    /**
 64     * Wraps a stream and chunks the output.
 65     * @param stream to wrap
 66     * @param bufferSize minimum chunk size (excluding last chunk)
 67     * @throws IOException
 68     *
 69     * @since 3.0
 70     */
 71    public ChunkedOutputStream(OutputStream stream, int bufferSize) throws IOException {
 72        this.cache = new byte[bufferSize];
 73        this.stream = stream;
 74    }
 75
 76    /**
 77     * Wraps a stream and chunks the output. The default buffer size of 2048 was chosen because
 78     * the chunk overhead is less than 0.5%
 79     * @param stream
 80     * @throws IOException
 81     */
 82    public ChunkedOutputStream(OutputStream stream) throws IOException {
 83        this(stream, 2048);
 84    }
 85
 86    // ----------------------------------------------------------- Internal methods
 87    /**
 88     * Writes the cache out onto the underlying stream
 89     * @throws IOException
 90     *
 91     * @since 3.0
 92     */
 93    protected void flushCache() throws IOException {
 94        if (cachePosition > 0) {
 95            byte chunkHeader[] = (Integer.toHexString(cachePosition) + "\r\n").getBytes("US-ASCII");
 96            stream.write(chunkHeader, 0, chunkHeader.length);
 97            stream.write(cache, 0, cachePosition);
 98            stream.write(ENDCHUNK, 0, ENDCHUNK.length);
 99            cachePosition = 0;
100        }
101    }
102
103    /**
104     * Writes the cache and bufferToAppend to the underlying stream
105     * as one large chunk
106     * @param bufferToAppend
107     * @param off
108     * @param len
109     * @throws IOException
110     *
111     * @since 3.0
112     */
113    protected void flushCacheWithAppend(byte bufferToAppend[], int off, int len) throws IOException {
114        byte chunkHeader[] = (Integer.toHexString(cachePosition + len) + "\r\n").getBytes("US-ASCII");
115        stream.write(chunkHeader, 0, chunkHeader.length);
116        stream.write(cache, 0, cachePosition);
117        stream.write(bufferToAppend, off, len);
118        stream.write(ENDCHUNK, 0, ENDCHUNK.length);
119        cachePosition = 0;
120    }
121
122    protected void writeClosingChunk() throws IOException {
123        // Write the final chunk.
124
125        stream.write(ZERO, 0, ZERO.length);
126        stream.write(CRLF, 0, CRLF.length);
127        stream.write(ENDCHUNK, 0, ENDCHUNK.length);
128    }
129
130    // ----------------------------------------------------------- Public Methods
131    /**
132     * Must be called to ensure the internal cache is flushed and the closing chunk is written.
133     * @throws IOException
134     *
135     * @since 3.0
136     */
137    public void finish() throws IOException {
138        if (!wroteLastChunk) {
139            flushCache();
140            writeClosingChunk();
141            wroteLastChunk = true;
142        }
143    }
144
145    // -------------------------------------------- OutputStream Methods
146    /**
147     * Write the specified byte to our output stream.
148     *
149     * Note: Avoid this method as it will cause an inefficient single byte chunk.
150     * Use write (byte[], int, int) instead.
151     *
152     * @param b The byte to be written
153     * @throws IOException if an input/output error occurs
154     */
155    public void write(int b) throws IOException {
156        cache[cachePosition] = (byte) b;
157        cachePosition++;
158        if (cachePosition == cache.length) flushCache();
159    }
160
161    /**
162     * Writes the array. If the array does not fit within the buffer, it is
163     * not split, but rather written out as one large chunk.
164     * @param b
165     * @throws IOException
166     *
167     * @since 3.0
168     */
169    @Override
170    public void write(byte b[]) throws IOException {
171        this.write(b, 0, b.length);
172    }
173
174    @Override
175    public void write(byte src[], int off, int len) throws IOException {
176        if (len >= cache.length - cachePosition) {
177            flushCacheWithAppend(src, off, len);
178        } else {
179            System.arraycopy(src, off, cache, cachePosition, len);
180            cachePosition += len;
181        }
182    }
183
184    /**
185     * Flushes the underlying stream, but leaves the internal buffer alone.
186     * @throws IOException
187     */
188    @Override
189    public void flush() throws IOException {
190        flushCache(); // Kohsuke: flush should flush the cache
191        stream.flush();
192    }
193
194    /**
195     * Finishes writing to the underlying stream, but does NOT close the underlying stream.
196     * @throws IOException
197     */
198    @Override
199    public void close() throws IOException {
200        finish();
201        super.close();
202    }
203}