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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 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();
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 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 {
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 }