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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.statemachine;
21  
22  import org.apache.mina.core.buffer.IoBuffer;
23  import org.apache.mina.filter.codec.ProtocolDecoderException;
24  import org.apache.mina.filter.codec.ProtocolDecoderOutput;
25  
26  /**
27   * {@link DecodingState} which consumes all received bytes until the session is
28   * closed.
29   *
30   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
31   */
32  public abstract class ConsumeToEndOfSessionDecodingState implements DecodingState {
33  
34      private IoBuffer buffer;
35      private final int maxLength;
36      
37      /**
38       * Creates a new instance using the specified maximum length.
39       * 
40       * @param maxLength the maximum number of bytes which will be consumed. If
41       *        this max is reached a {@link ProtocolDecoderException} will be 
42       *        thrown by {@link #decode(IoBuffer, ProtocolDecoderOutput)}.
43       */
44      public ConsumeToEndOfSessionDecodingState(int maxLength) {
45          this.maxLength = maxLength;
46      }
47  
48      /**
49       * {@inheritDoc}
50       */
51      public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
52              throws Exception {
53          if (buffer == null) {
54              buffer = IoBuffer.allocate(256).setAutoExpand(true);
55          }
56  
57          if (buffer.position() + in.remaining() > maxLength) {
58              throw new ProtocolDecoderException("Received data exceeds " + maxLength + " byte(s).");
59          }
60          buffer.put(in);
61          return this;
62      }
63  
64      /**
65       * {@inheritDoc}
66       */
67      public DecodingState finishDecode(ProtocolDecoderOutput out)
68              throws Exception {
69          try {
70              if (buffer == null) {
71                  buffer = IoBuffer.allocate(0);
72              }
73              buffer.flip();
74              return finishDecode(buffer, out);
75          } finally {
76              buffer = null;
77          }
78      }
79  
80      /**
81       * Invoked when this state has consumed all bytes until the session is 
82       * closed.
83       * 
84       * @param product the bytes read.
85       * @param out the current {@link ProtocolDecoderOutput} used to write 
86       *        decoded messages.
87       * @return the next state if a state transition was triggered (use 
88       *         <code>this</code> for loop transitions) or <code>null</code> if 
89       *         the state machine has reached its end.
90       * @throws Exception if the read data violated protocol specification.
91       */
92      protected abstract DecodingState finishDecode(IoBuffer product,
93              ProtocolDecoderOutput out) throws Exception;
94  }