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.ProtocolDecoderOutput; 024 025/** 026 * {@link DecodingState} which consumes all bytes until a fixed (ASCII) 027 * character is reached. The terminator is skipped. 028 * 029 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 030 */ 031public abstract class ConsumeToDynamicTerminatorDecodingState implements DecodingState { 032 033 private IoBuffer buffer; 034 035 /** 036 * {@inheritDoc} 037 */ 038 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception { 039 int beginPos = in.position(); 040 int terminatorPos = -1; 041 int limit = in.limit(); 042 043 for (int i = beginPos; i < limit; i++) { 044 byte b = in.get(i); 045 if (isTerminator(b)) { 046 terminatorPos = i; 047 break; 048 } 049 } 050 051 if (terminatorPos >= 0) { 052 IoBuffer product; 053 054 if (beginPos < terminatorPos) { 055 in.limit(terminatorPos); 056 057 if (buffer == null) { 058 product = in.slice(); 059 } else { 060 buffer.put(in); 061 product = buffer.flip(); 062 buffer = null; 063 } 064 065 in.limit(limit); 066 } else { 067 // When input contained only terminator rather than actual data... 068 if (buffer == null) { 069 product = IoBuffer.allocate(0); 070 } else { 071 product = buffer.flip(); 072 buffer = null; 073 } 074 } 075 in.position(terminatorPos + 1); 076 return finishDecode(product, out); 077 } 078 079 if (buffer == null) { 080 buffer = IoBuffer.allocate(in.remaining()); 081 buffer.setAutoExpand(true); 082 } 083 buffer.put(in); 084 return this; 085 } 086 087 /** 088 * {@inheritDoc} 089 */ 090 public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception { 091 IoBuffer product; 092 // When input contained only terminator rather than actual data... 093 if (buffer == null) { 094 product = IoBuffer.allocate(0); 095 } else { 096 product = buffer.flip(); 097 buffer = null; 098 } 099 return finishDecode(product, out); 100 } 101 102 /** 103 * Determines whether the specified <code>byte</code> is a terminator. 104 * 105 * @param b the <code>byte</code> to check. 106 * @return <tt>true</tt> if <code>b</code> is a terminator, 107 * <tt>false</tt> otherwise. 108 */ 109 protected abstract boolean isTerminator(byte b); 110 111 /** 112 * Invoked when this state has reached the terminator byte. 113 * 114 * @param product the read bytes not including the terminator. 115 * @param out the current {@link ProtocolDecoderOutput} used to write 116 * decoded messages. 117 * @return the next state if a state transition was triggered (use 118 * <code>this</code> for loop transitions) or <code>null</code> if 119 * the state machine has reached its end. 120 * @throws Exception if the read data violated protocol specification. 121 */ 122 protected abstract DecodingState finishDecode(IoBuffer product, ProtocolDecoderOutput out) throws Exception; 123}