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>byte</code> values.
28 *
29 * @author The Apache MINA Project (dev@mina.apache.org)
30 */
31 public abstract class SingleByteDecodingState implements DecodingState {
32
33 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
34 throws Exception {
35 if (in.hasRemaining()) {
36 return finishDecode(in.get(), out);
37 }
38
39 return this;
40 }
41
42 /**
43 * {@inheritDoc}
44 */
45 public DecodingState finishDecode(ProtocolDecoderOutput out)
46 throws Exception {
47 throw new ProtocolDecoderException(
48 "Unexpected end of session while waiting for a single byte.");
49 }
50
51 /**
52 * Invoked when this state has consumed a complete <code>byte</code>.
53 *
54 * @param b the byte.
55 * @param out the current {@link ProtocolDecoderOutput} used to write
56 * decoded messages.
57 * @return the next state if a state transition was triggered (use
58 * <code>this</code> for loop transitions) or <code>null</code> if
59 * the state machine has reached its end.
60 * @throws Exception if the read data violated protocol specification.
61 */
62 protected abstract DecodingState finishDecode(byte b,
63 ProtocolDecoderOutput out) throws Exception;
64 }