1/*
2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/impl/io/ChunkedOutputStream.java $
3 * $Revision: 645081 $
4 * $Date: 2008-04-05 04:36:42 -0700 (Sat, 05 Apr 2008) $
5 *
6 * ====================================================================
7 * Licensed to the Apache Software Foundation (ASF) under one
8 * or more contributor license agreements.  See the NOTICE file
9 * distributed with this work for additional information
10 * regarding copyright ownership.  The ASF licenses this file
11 * to you under the Apache License, Version 2.0 (the
12 * "License"); you may not use this file except in compliance
13 * with 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,
18 * software distributed under the License is distributed on an
19 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
20 * KIND, either express or implied.  See the License for the
21 * specific language governing permissions and limitations
22 * under the License.
23 * ====================================================================
24 *
25 * This software consists of voluntary contributions made by many
26 * individuals on behalf of the Apache Software Foundation.  For more
27 * information on the Apache Software Foundation, please see
28 * <http://www.apache.org/>.
29 *
30 */
31
32package org.apache.http.impl.io;
33
34import java.io.IOException;
35import java.io.OutputStream;
36
37import org.apache.http.io.SessionOutputBuffer;
38
39/**
40 * Implements chunked transfer coding.
41 * See <a href="http://www.w3.org/Protocols/rfc2616/rfc2616.txt">RFC 2616</a>,
42 * <a href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec3.html#sec3.6">section 3.6.1</a>.
43 * Writes are buffered to an internal buffer (2048 default size).
44 *
45 * @author Mohammad Rezaei (Goldman, Sachs &amp; Co.)
46 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a>
47 *
48 * @since 4.0
49 */
50public class ChunkedOutputStream extends OutputStream {
51
52    // ----------------------------------------------------- Instance Variables
53    private final SessionOutputBuffer out;
54
55    private byte[] cache;
56
57    private int cachePosition = 0;
58
59    private boolean wroteLastChunk = false;
60
61    /** True if the stream is closed. */
62    private boolean closed = false;
63
64    // ----------------------------------------------------------- Constructors
65    /**
66     * Wraps a session output buffer and chunks the output.
67     * @param out the session output buffer to wrap
68     * @param bufferSize minimum chunk size (excluding last chunk)
69     * @throws IOException
70     */
71    public ChunkedOutputStream(final SessionOutputBuffer out, int bufferSize)
72            throws IOException {
73        super();
74        this.cache = new byte[bufferSize];
75        this.out = out;
76    }
77
78    /**
79     * Wraps a session output buffer and chunks the output. The default buffer
80     * size of 2048 was chosen because the chunk overhead is less than 0.5%
81     *
82     * @param out       the output buffer to wrap
83     * @throws IOException
84     */
85    public ChunkedOutputStream(final SessionOutputBuffer out)
86            throws IOException {
87        this(out, 2048);
88    }
89
90    // ----------------------------------------------------------- Internal methods
91    /**
92     * Writes the cache out onto the underlying stream
93     * @throws IOException
94     */
95    protected void flushCache() throws IOException {
96        if (this.cachePosition > 0) {
97            this.out.writeLine(Integer.toHexString(this.cachePosition));
98            this.out.write(this.cache, 0, this.cachePosition);
99            this.out.writeLine("");
100            this.cachePosition = 0;
101        }
102    }
103
104    /**
105     * Writes the cache and bufferToAppend to the underlying stream
106     * as one large chunk
107     * @param bufferToAppend
108     * @param off
109     * @param len
110     * @throws IOException
111     */
112    protected void flushCacheWithAppend(byte bufferToAppend[], int off, int len) throws IOException {
113        this.out.writeLine(Integer.toHexString(this.cachePosition + len));
114        this.out.write(this.cache, 0, this.cachePosition);
115        this.out.write(bufferToAppend, off, len);
116        this.out.writeLine("");
117        this.cachePosition = 0;
118    }
119
120    protected void writeClosingChunk() throws IOException {
121        // Write the final chunk.
122        this.out.writeLine("0");
123        this.out.writeLine("");
124    }
125
126    // ----------------------------------------------------------- Public Methods
127    /**
128     * Must be called to ensure the internal cache is flushed and the closing chunk is written.
129     * @throws IOException
130     */
131    public void finish() throws IOException {
132        if (!this.wroteLastChunk) {
133            flushCache();
134            writeClosingChunk();
135            this.wroteLastChunk = true;
136        }
137    }
138
139    // -------------------------------------------- OutputStream Methods
140    public void write(int b) throws IOException {
141        if (this.closed) {
142            throw new IOException("Attempted write to closed stream.");
143        }
144        this.cache[this.cachePosition] = (byte) b;
145        this.cachePosition++;
146        if (this.cachePosition == this.cache.length) flushCache();
147    }
148
149    /**
150     * Writes the array. If the array does not fit within the buffer, it is
151     * not split, but rather written out as one large chunk.
152     * @param b
153     * @throws IOException
154     */
155    public void write(byte b[]) throws IOException {
156        write(b, 0, b.length);
157    }
158
159    public void write(byte src[], int off, int len) throws IOException {
160        if (this.closed) {
161            throw new IOException("Attempted write to closed stream.");
162        }
163        if (len >= this.cache.length - this.cachePosition) {
164            flushCacheWithAppend(src, off, len);
165        } else {
166            System.arraycopy(src, off, cache, this.cachePosition, len);
167            this.cachePosition += len;
168        }
169    }
170
171    /**
172     * Flushes the content buffer and the underlying stream.
173     * @throws IOException
174     */
175    public void flush() throws IOException {
176        flushCache();
177        this.out.flush();
178    }
179
180    /**
181     * Finishes writing to the underlying stream, but does NOT close the underlying stream.
182     * @throws IOException
183     */
184    public void close() throws IOException {
185        if (!this.closed) {
186            this.closed = true;
187            finish();
188            this.out.flush();
189        }
190    }
191}
192