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Java > Open Source Codes > org > apache > mina > filter > StreamWriteFilter


1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one
3  * or more contributor license agreements. See the NOTICE file
4  * distributed with this work for additional information
5  * regarding copyright ownership. The ASF licenses this file
6  * to you under the Apache License, Version 2.0 (the
7  * "License"); you may not use this file except in compliance
8  * with the License. You may obtain a copy of the License at
9  *
10  * http://www.apache.org/licenses/LICENSE-2.0
11  *
12  * Unless required by applicable law or agreed to in writing,
13  * software distributed under the License is distributed on an
14  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15  * KIND, either express or implied. See the License for the
16  * specific language governing permissions and limitations
17  * under the License.
18  *
19  */
20 package org.apache.mina.filter;
21
22 import java.io.IOException JavaDoc;
23 import java.io.InputStream JavaDoc;
24 import java.util.Queue JavaDoc;
25 import java.util.concurrent.ConcurrentLinkedQueue JavaDoc;
26
27 import org.apache.mina.common.ByteBuffer;
28 import org.apache.mina.common.IoFilterAdapter;
29 import org.apache.mina.common.IoSession;
30 import org.apache.mina.common.WriteFuture;
31
32 /**
33  * Filter implementation which makes it possible to write {@link InputStream}
34  * objects directly using {@link IoSession#write(Object)}. When an
35  * {@link InputStream} is written to a session this filter will read the bytes
36  * from the stream into {@link ByteBuffer} objects and write those buffers
37  * to the next filter. When end of stream has been reached this filter will
38  * call {@link NextFilter#messageSent(IoSession, Object)} using the original
39  * {@link InputStream} written to the session and notifies
40  * {@link org.apache.mina.common.WriteFuture} on the
41  * original {@link org.apache.mina.common.IoFilter.WriteRequest}.
42  * <p/>
43  * This filter will ignore written messages which aren't {@link InputStream}
44  * instances. Such messages will be passed to the next filter directly.
45  * </p>
46  * <p/>
47  * NOTE: this filter does not close the stream after all data from stream
48  * has been written. The {@link org.apache.mina.common.IoHandler} should take
49  * care of that in its
50  * {@link org.apache.mina.common.IoHandler#messageSent(IoSession, Object)}
51  * callback.
52  * </p>
53  *
54  * @author The Apache Directory Project (mina-dev@directory.apache.org)
55  * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (금, 13 7월 2007) $
56  */
57 public class StreamWriteFilter extends IoFilterAdapter {
58     /**
59      * The default buffer size this filter uses for writing.
60      */
61     public static final int DEFAULT_STREAM_BUFFER_SIZE = 4096;
62
63     /**
64      * The attribute name used when binding the {@link InputStream} to the session.
65      */
66     public static final String JavaDoc CURRENT_STREAM = StreamWriteFilter.class
67             .getName()
68             + ".stream";
69
70     protected static final String JavaDoc WRITE_REQUEST_QUEUE = StreamWriteFilter.class
71             .getName()
72             + ".queue";
73
74     protected static final String JavaDoc INITIAL_WRITE_FUTURE = StreamWriteFilter.class
75             .getName()
76             + ".future";
77
78     private int writeBufferSize = DEFAULT_STREAM_BUFFER_SIZE;
79
80     @Override JavaDoc
81     public void filterWrite(NextFilter nextFilter, IoSession session,
82             WriteRequest writeRequest) throws Exception JavaDoc {
83         // If we're already processing a stream we need to queue the WriteRequest.
84 if (session.getAttribute(CURRENT_STREAM) != null) {
85             Queue JavaDoc<WriteRequest> queue = getWriteRequestQueue(session);
86             if (queue == null) {
87                 queue = new ConcurrentLinkedQueue JavaDoc<WriteRequest>();
88                 session.setAttribute(WRITE_REQUEST_QUEUE, queue);
89             }
90             queue.add(writeRequest);
91             return;
92         }
93
94         Object JavaDoc message = writeRequest.getMessage();
95
96         if (message instanceof InputStream JavaDoc) {
97
98             InputStream JavaDoc inputStream = (InputStream JavaDoc) message;
99
100             ByteBuffer byteBuffer = getNextByteBuffer(inputStream);
101             if (byteBuffer == null) {
102                 // End of stream reached.
103 writeRequest.getFuture().setWritten(true);
104                 nextFilter.messageSent(session, message);
105             } else {
106                 session.setAttribute(CURRENT_STREAM, inputStream);
107                 session.setAttribute(INITIAL_WRITE_FUTURE, writeRequest
108                         .getFuture());
109
110                 nextFilter.filterWrite(session, new WriteRequest(byteBuffer));
111             }
112
113         } else {
114             nextFilter.filterWrite(session, writeRequest);
115         }
116     }
117
118     @SuppressWarnings JavaDoc("unchecked")
119     private Queue JavaDoc<WriteRequest> getWriteRequestQueue(IoSession session) {
120         return (Queue JavaDoc<WriteRequest>) session.getAttribute(WRITE_REQUEST_QUEUE);
121     }
122
123     @Override JavaDoc
124     public void messageSent(NextFilter nextFilter, IoSession session,
125             Object JavaDoc message) throws Exception JavaDoc {
126         InputStream JavaDoc inputStream = (InputStream JavaDoc) session
127                 .getAttribute(CURRENT_STREAM);
128
129         if (inputStream == null) {
130             nextFilter.messageSent(session, message);
131         } else {
132             ByteBuffer byteBuffer = getNextByteBuffer(inputStream);
133
134             if (byteBuffer == null) {
135                 // End of stream reached.
136 session.removeAttribute(CURRENT_STREAM);
137                 WriteFuture writeFuture = (WriteFuture) session
138                         .removeAttribute(INITIAL_WRITE_FUTURE);
139
140                 // Write queued WriteRequests.
141 Queue JavaDoc<? extends WriteRequest> queue = (Queue JavaDoc<? extends WriteRequest>) session
142                         .removeAttribute(WRITE_REQUEST_QUEUE);
143                 if (queue != null) {
144                     WriteRequest wr = queue.poll();
145                     while (wr != null) {
146                         filterWrite(nextFilter, session, wr);
147                         wr = queue.poll();
148                     }
149                 }
150
151                 writeFuture.setWritten(true);
152                 nextFilter.messageSent(session, inputStream);
153             } else {
154                 nextFilter.filterWrite(session, new WriteRequest(byteBuffer));
155             }
156         }
157     }
158
159     private ByteBuffer getNextByteBuffer(InputStream JavaDoc is) throws IOException JavaDoc {
160         byte[] bytes = new byte[writeBufferSize];
161
162         int off = 0;
163         int n = 0;
164         while (off < bytes.length
165                 && (n = is.read(bytes, off, bytes.length - off)) != -1) {
166             off += n;
167         }
168
169         if (n == -1 && off == 0) {
170             return null;
171         }
172
173         return ByteBuffer.wrap(bytes, 0, off);
174     }
175
176     /**
177      * Returns the size of the write buffer in bytes. Data will be read from the
178      * stream in chunks of this size and then written to the next filter.
179      *
180      * @return the write buffer size.
181      */
182     public int getWriteBufferSize() {
183         return writeBufferSize;
184     }
185
186     /**
187      * Sets the size of the write buffer in bytes. Data will be read from the
188      * stream in chunks of this size and then written to the next filter.
189      *
190      * @throws IllegalArgumentException if the specified size is &lt; 1.
191      */
192     public void setWriteBufferSize(int writeBufferSize) {
193         if (writeBufferSize < 1) {
194             throw new IllegalArgumentException JavaDoc(
195                     "writeBufferSize must be at least 1");
196         }
197         this.writeBufferSize = writeBufferSize;
198     }
199
200 }
201
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