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 received bytes until a configured 027 * number of read bytes has been reached. Please note that this state can 028 * produce a buffer with less data than the configured length if the associated 029 * session has been closed unexpectedly. 030 * 031 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 032 */ 033public abstract class FixedLengthDecodingState implements DecodingState { 034 035 private final int length; 036 037 private IoBuffer buffer; 038 039 /** 040 * Constructs a new instance using the specified decode length. 041 * 042 * @param length the number of bytes to read. 043 */ 044 public FixedLengthDecodingState(int length) { 045 this.length = length; 046 } 047 048 /** 049 * {@inheritDoc} 050 */ 051 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) throws Exception { 052 if (buffer == null) { 053 if (in.remaining() >= length) { 054 int limit = in.limit(); 055 in.limit(in.position() + length); 056 IoBuffer product = in.slice(); 057 in.position(in.position() + length); 058 in.limit(limit); 059 return finishDecode(product, out); 060 } 061 062 buffer = IoBuffer.allocate(length); 063 buffer.put(in); 064 return this; 065 } 066 067 if (in.remaining() >= length - buffer.position()) { 068 int limit = in.limit(); 069 in.limit(in.position() + length - buffer.position()); 070 buffer.put(in); 071 in.limit(limit); 072 IoBuffer product = this.buffer; 073 this.buffer = null; 074 return finishDecode(product.flip(), out); 075 } 076 077 buffer.put(in); 078 return this; 079 } 080 081 /** 082 * {@inheritDoc} 083 */ 084 public DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception { 085 IoBuffer readData; 086 if (buffer == null) { 087 readData = IoBuffer.allocate(0); 088 } else { 089 readData = buffer.flip(); 090 buffer = null; 091 } 092 return finishDecode(readData, out); 093 } 094 095 /** 096 * Invoked when this state has consumed the configured number of bytes. 097 * 098 * @param product the data. 099 * @param out the current {@link ProtocolDecoderOutput} used to write 100 * decoded messages. 101 * @return the next state if a state transition was triggered (use 102 * <code>this</code> for loop transitions) or <code>null</code> if 103 * the state machine has reached its end. 104 * @throws Exception if the read data violated protocol specification. 105 */ 106 protected abstract DecodingState finishDecode(IoBuffer product, ProtocolDecoderOutput out) throws Exception; 107}