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 decodes <code>int</code> values in big-endian
28 * order (high bytes come first).
29 *
30 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
31 */
32 public abstract class IntegerDecodingState implements DecodingState {
33 private int counter;
34
35 /**
36 * {@inheritDoc}
37 */
38 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception {
39 int firstByte = 0;
40 int secondByte = 0;
41 int thirdByte = 0;
42
43 while (in.hasRemaining()) {
44 switch (counter) {
45 case 0:
46 firstByte = in.getUnsigned();
47 break;
48
49 case 1:
50 secondByte = in.getUnsigned();
51 break;
52
53 case 2:
54 thirdByte = in.getUnsigned();
55 break;
56
57 case 3:
58 counter = 0;
59 return finishDecode((firstByte << 24) | (secondByte << 16) | (thirdByte << 8) | in.getUnsigned(), out);
60
61 default:
62 throw new InternalError();
63 }
64
65 counter++;
66 }
67
68 return this;
69 }
70
71 /**
72 * {@inheritDoc}
73 */
74 public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception {
75 throw new ProtocolDecoderException("Unexpected end of session while waiting for an integer.");
76 }
77
78 /**
79 * Invoked when this state has consumed a complete <code>int</code>.
80 *
81 * @param value the integer.
82 * @param out the current {@link ProtocolDecoderOutput} used to write
83 * decoded messages.
84 * @return the next state if a state transition was triggered (use
85 * <code>this</code> for loop transitions) or <code>null</code> if
86 * the state machine has reached its end.
87 * @throws Exception if the read data violated protocol specification.
88 */
89 protected abstract DecodingState finishDecode(int value, ProtocolDecoderOutput out) throws Exception;
90 }