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Java > Open Source Codes > org > apache > mina > filter > codec > netty > NettyDecoder


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.codec.netty;
21
22 import net.gleamynode.netty2.Message;
23 import net.gleamynode.netty2.MessageParseException;
24 import net.gleamynode.netty2.MessageRecognizer;
25
26 import org.apache.mina.common.ByteBuffer;
27 import org.apache.mina.common.IoSession;
28 import org.apache.mina.filter.codec.ProtocolDecoder;
29 import org.apache.mina.filter.codec.ProtocolDecoderAdapter;
30 import org.apache.mina.filter.codec.ProtocolDecoderException;
31 import org.apache.mina.filter.codec.ProtocolDecoderOutput;
32
33 /**
34  * A MINA {@link ProtocolDecoder} that decodes byte buffers into
35  * Netty2 {@link Message}s using specified {@link MessageRecognizer}s.
36  *
37  * @author The Apache Directory Project (mina-dev@directory.apache.org)
38  * @version $Rev: 555855 $, $Date: 2007-07-13 12:19:00 +0900 (금, 13 7월 2007) $,
39  */
40 public class NettyDecoder extends ProtocolDecoderAdapter {
41     private final MessageRecognizer recognizer;
42
43     private java.nio.ByteBuffer JavaDoc readBuf = java.nio.ByteBuffer.allocate(1024);
44
45     private Message readingMessage;
46
47     /**
48      * Creates a new instance with the specified {@link MessageRecognizer}.
49      */
50     public NettyDecoder(MessageRecognizer recognizer) {
51         if (recognizer == null)
52             throw new NullPointerException JavaDoc();
53
54         this.recognizer = recognizer;
55     }
56
57     private void put(ByteBuffer in) {
58         // copy to read buffer
59 if (in.remaining() > readBuf.remaining())
60             expand((readBuf.position() + in.remaining()) * 3 / 2);
61         readBuf.put(in.buf());
62     }
63
64     private void expand(int newCapacity) {
65         java.nio.ByteBuffer JavaDoc newBuf = java.nio.ByteBuffer.allocate(newCapacity);
66         readBuf.flip();
67         newBuf.put(readBuf);
68         readBuf = newBuf;
69     }
70
71     public void decode(IoSession session, ByteBuffer in,
72             ProtocolDecoderOutput out) throws Exception JavaDoc {
73         put(in);
74
75         Message m = readingMessage;
76         try {
77             for (;;) {
78                 readBuf.flip();
79                 if (m == null) {
80                     int limit = readBuf.limit();
81                     boolean failed = true;
82                     try {
83                         m = recognizer.recognize(readBuf);
84                         failed = false;
85                     } finally {
86                         if (failed) {
87                             // clear the read buffer if failed to recognize
88 readBuf.clear();
89                             break;
90                         } else {
91                             if (m == null) {
92                                 readBuf.limit(readBuf.capacity());
93                                 readBuf.position(limit);
94                                 break; // finish decoding
95 } else {
96                                 // reset buffer for read
97 readBuf.limit(limit);
98                                 readBuf.position(0);
99                             }
100                         }
101                     }
102                 }
103
104                 if (m != null) {
105                     try {
106                         if (m.read(readBuf)) {
107                             out.write(m);
108                             m = null;
109                         } else {
110                             break;
111                         }
112                     } finally {
113                         if (readBuf.hasRemaining()) {
114                             readBuf.compact();
115                         } else {
116                             readBuf.clear();
117                             break;
118                         }
119                     }
120                 }
121             }
122         } catch (MessageParseException e) {
123             m = null; // discard reading message
124 throw new ProtocolDecoderException("Failed to decode.", e);
125         } finally {
126             readingMessage = m;
127         }
128     }
129 }
130
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