001/* 002 * Licensed to the Apache Software Foundation (ASF) under one 003 * or more contributor license agreements. See the NOTICE file 004 * distributed with this work for additional information 005 * regarding copyright ownership. The ASF licenses this file 006 * to you under the Apache License, Version 2.0 (the 007 * "License"); you may not use this file except in compliance 008 * with the License. You may obtain a copy of the License at 009 * 010 * http://www.apache.org/licenses/LICENSE-2.0 011 * 012 * Unless required by applicable law or agreed to in writing, 013 * software distributed under the License is distributed on an 014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 * KIND, either express or implied. See the License for the 016 * specific language governing permissions and limitations 017 * under the License. 018 * 019 */ 020package org.apache.mina.filter.codec.statemachine; 021 022import org.apache.mina.core.buffer.IoBuffer; 023import org.apache.mina.filter.codec.ProtocolDecoderException; 024import org.apache.mina.filter.codec.ProtocolDecoderOutput; 025 026/** 027 * {@link DecodingState} which decodes <code>byte</code> values. 028 * 029 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 030 */ 031public abstract class SingleByteDecodingState implements DecodingState { 032 033 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception { 034 if (in.hasRemaining()) { 035 return finishDecode(in.get(), out); 036 } 037 038 return this; 039 } 040 041 /** 042 * {@inheritDoc} 043 */ 044 public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception { 045 throw new ProtocolDecoderException("Unexpected end of session while waiting for a single byte."); 046 } 047 048 /** 049 * Invoked when this state has consumed a complete <code>byte</code>. 050 * 051 * @param b the byte. 052 * @param out the current {@link ProtocolDecoderOutput} used to write 053 * decoded messages. 054 * @return the next state if a state transition was triggered (use 055 * <code>this</code> for loop transitions) or <code>null</code> if 056 * the state machine has reached its end. 057 * @throws Exception if the read data violated protocol specification. 058 */ 059 protected abstract DecodingState finishDecode(byte b, ProtocolDecoderOutput out) throws Exception; 060}