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1   /*
2    * $HeadURL: https://svn.apache.org/repos/asf/httpcomponents/oac.hc3x/trunk/src/java/org/apache/commons/httpclient/ChunkedOutputStream.java $
3    * $Revision: 1425331 $
4    * $Date: 2012-12-22 19:29:41 +0100 (Sat, 22 Dec 2012) $
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  
31  package org.apache.commons.httpclient;
32  
33  import java.io.IOException;
34  import java.io.OutputStream;
35  
36  import org.apache.commons.httpclient.util.EncodingUtil;
37  
38  /***
39   * Implements HTTP chunking support. Writes are buffered to an internal buffer (2048 default size).
40   * Chunks are guaranteed to be at least as large as the buffer size (except for the last chunk).
41   *
42   * @author Mohammad Rezaei, Goldman, Sachs & Co.
43   */
44  public class ChunkedOutputStream extends OutputStream {
45  
46      // ------------------------------------------------------- Static Variables
47      private static final byte CRLF[] = new byte[] {(byte) 13, (byte) 10};
48  
49      /*** End chunk */
50      private static final byte ENDCHUNK[] = CRLF;
51  
52      /*** 0 */
53      private static final byte ZERO[] = new byte[] {(byte) '0'};
54  
55      // ----------------------------------------------------- Instance Variables
56      private OutputStream stream = null;
57  
58      private byte[] cache;
59  
60      private int cachePosition = 0;
61  
62      private boolean wroteLastChunk = false;
63  
64      // ----------------------------------------------------------- Constructors
65      /***
66       * Wraps a stream and chunks the output.
67       * @param stream to wrap
68       * @param bufferSize minimum chunk size (excluding last chunk)
69       * @throws IOException
70       * 
71       * @since 3.0
72       */
73      public ChunkedOutputStream(OutputStream stream, int bufferSize) throws IOException {
74          this.cache = new byte[bufferSize];
75          this.stream = stream;
76      }
77  
78      /***
79       * Wraps a stream and chunks the output. The default buffer size of 2048 was chosen because
80       * the chunk overhead is less than 0.5%
81       * @param stream
82       * @throws IOException
83       */
84      public ChunkedOutputStream(OutputStream stream) throws IOException {
85          this(stream, 2048);
86      }
87  
88      // ----------------------------------------------------------- Internal methods
89      /***
90       * Writes the cache out onto the underlying stream
91       * @throws IOException
92       * 
93       * @since 3.0
94       */
95      protected void flushCache() throws IOException {
96          if (cachePosition > 0) {
97              byte chunkHeader[] = EncodingUtil.getAsciiBytes(
98                      Integer.toHexString(cachePosition) + "\r\n");
99              stream.write(chunkHeader, 0, chunkHeader.length);
100             stream.write(cache, 0, cachePosition);
101             stream.write(ENDCHUNK, 0, ENDCHUNK.length);
102             cachePosition = 0;
103         }
104     }
105 
106     /***
107      * Writes the cache and bufferToAppend to the underlying stream
108      * as one large chunk
109      * @param bufferToAppend
110      * @param off
111      * @param len
112      * @throws IOException
113      * 
114      * @since 3.0
115      */
116     protected void flushCacheWithAppend(byte bufferToAppend[], int off, int len) throws IOException {
117         byte chunkHeader[] = EncodingUtil.getAsciiBytes(
118                 Integer.toHexString(cachePosition + len) + "\r\n");
119         stream.write(chunkHeader, 0, chunkHeader.length);
120         stream.write(cache, 0, cachePosition);
121         stream.write(bufferToAppend, off, len);
122         stream.write(ENDCHUNK, 0, ENDCHUNK.length);
123         cachePosition = 0;
124     }
125 
126     protected void writeClosingChunk() throws IOException {
127         // Write the final chunk.
128 
129         stream.write(ZERO, 0, ZERO.length);
130         stream.write(CRLF, 0, CRLF.length);
131         stream.write(ENDCHUNK, 0, ENDCHUNK.length);
132     }
133 
134     // ----------------------------------------------------------- Public Methods
135     /***
136      * Must be called to ensure the internal cache is flushed and the closing chunk is written.
137      * @throws IOException
138      * 
139      * @since 3.0
140      */
141     public void finish() throws IOException {
142         if (!wroteLastChunk) {
143             flushCache();
144             writeClosingChunk();
145             wroteLastChunk = true;
146         }
147     }
148 
149     // -------------------------------------------- OutputStream Methods
150     /***
151      * Write the specified byte to our output stream.
152      * 
153      * Note: Avoid this method as it will cause an inefficient single byte chunk. 
154      * Use write (byte[], int, int) instead.
155      * 
156      * @param b The byte to be written
157      * @throws IOException if an input/output error occurs
158      */
159     public void write(int b) throws IOException {
160         cache[cachePosition] = (byte) b;
161         cachePosition++;
162         if (cachePosition == cache.length) flushCache();
163     }
164 
165     /***
166      * Writes the array. If the array does not fit within the buffer, it is
167      * not split, but rather written out as one large chunk.
168      * @param b
169      * @throws IOException
170      * 
171      * @since 3.0
172      */
173     public void write(byte b[]) throws IOException {
174         this.write(b, 0, b.length);
175     }
176 
177     public void write(byte src[], int off, int len) throws IOException {
178         if (len >= cache.length - cachePosition) {
179             flushCacheWithAppend(src, off, len);
180         } else {
181             System.arraycopy(src, off, cache, cachePosition, len);
182             cachePosition += len;
183         }
184     }
185 
186     /***
187      * Flushes the underlying stream, but leaves the internal buffer alone.
188      * @throws IOException
189      */
190     public void flush() throws IOException {
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     public void close() throws IOException {
199         finish();
200         super.close();
201     }
202 }