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 */
32 public abstract class IntegerDecodingState implements DecodingState {
33
34 private int firstByte;
35 private int secondByte;
36 private int thirdByte;
37 private int counter;
38
39 /**
40 * {@inheritDoc}
41 */
42 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
43 throws Exception {
44 while (in.hasRemaining()) {
45 switch (counter) {
46 case 0:
47 firstByte = in.getUnsigned();
48 break;
49 case 1:
50 secondByte = in.getUnsigned();
51 break;
52 case 2:
53 thirdByte = in.getUnsigned();
54 break;
55 case 3:
56 counter = 0;
57 return finishDecode(
58 (firstByte << 24) | (secondByte << 16) | (thirdByte << 8) | in.getUnsigned(),
59 out);
60 default:
61 throw new InternalError();
62 }
63 counter ++;
64 }
65
66 return this;
67 }
68
69 /**
70 * {@inheritDoc}
71 */
72 public DecodingState finishDecode(ProtocolDecoderOutput out)
73 throws Exception {
74 throw new ProtocolDecoderException(
75 "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,
90 ProtocolDecoderOutput out) throws Exception;
91 }