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 The Apache MINA Project (dev@mina.apache.org)
31 * @version $Rev: 671827 $, $Date: 2008-06-26 10:49:48 +0200 (jeu, 26 jun 2008) $
32 */
33 public abstract class IntegerDecodingState implements DecodingState {
34
35 private int firstByte;
36 private int secondByte;
37 private int thirdByte;
38 private int counter;
39
40 /**
41 * {@inheritDoc}
42 */
43 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
44 throws Exception {
45 while (in.hasRemaining()) {
46 switch (counter) {
47 case 0:
48 firstByte = in.getUnsigned();
49 break;
50 case 1:
51 secondByte = in.getUnsigned();
52 break;
53 case 2:
54 thirdByte = in.getUnsigned();
55 break;
56 case 3:
57 counter = 0;
58 return finishDecode(
59 (firstByte << 24) | (secondByte << 16) | (thirdByte << 8) | in.getUnsigned(),
60 out);
61 default:
62 throw new InternalError();
63 }
64 counter ++;
65 }
66
67 return this;
68 }
69
70 /**
71 * {@inheritDoc}
72 */
73 public DecodingState finishDecode(ProtocolDecoderOutput out)
74 throws Exception {
75 throw new ProtocolDecoderException(
76 "Unexpected end of session while waiting for an integer.");
77 }
78
79 /**
80 * Invoked when this state has consumed a complete <code>int</code>.
81 *
82 * @param value the integer.
83 * @param out the current {@link ProtocolDecoderOutput} used to write
84 * decoded messages.
85 * @return the next state if a state transition was triggered (use
86 * <code>this</code> for loop transitions) or <code>null</code> if
87 * the state machine has reached its end.
88 * @throws Exception if the read data violated protocol specification.
89 */
90 protected abstract DecodingState finishDecode(int value,
91 ProtocolDecoderOutput out) throws Exception;
92 }