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.ProtocolDecoderOutput; 24 25 /** 26 * {@link DecodingState} which skips data until {@link #canSkip(byte)} returns 27 * <tt>false</tt>. 28 * 29 * @author The Apache MINA Project (dev@mina.apache.org) 30 */ 31 public abstract class SkippingState implements DecodingState { 32 33 private int skippedBytes; 34 35 /** 36 * {@inheritDoc} 37 */ 38 public DecodingState decode(IoBuffer in, ProtocolDecoderOutput out) 39 throws Exception { 40 int beginPos = in.position(); 41 int limit = in.limit(); 42 for (int i = beginPos; i < limit; i++) { 43 byte b = in.get(i); 44 if (!canSkip(b)) { 45 in.position(i); 46 int answer = this.skippedBytes; 47 this.skippedBytes = 0; 48 return finishDecode(answer); 49 } 50 51 skippedBytes++; 52 } 53 54 in.position(limit); 55 return this; 56 } 57 58 /** 59 * {@inheritDoc} 60 */ 61 public DecodingState finishDecode(ProtocolDecoderOutput out) 62 throws Exception { 63 return finishDecode(skippedBytes); 64 } 65 66 /** 67 * Called to determine whether the specified byte can be skipped. 68 * 69 * @param b the byte to check. 70 * @return <code>true</code> if the byte can be skipped. 71 */ 72 protected abstract boolean canSkip(byte b); 73 74 /** 75 * Invoked when this state cannot skip any more bytes. 76 * 77 * @param skippedBytes the number of bytes skipped. 78 * @return the next state if a state transition was triggered (use 79 * <code>this</code> for loop transitions) or <code>null</code> if 80 * the state machine has reached its end. 81 * @throws Exception if the read data violated protocol specification. 82 */ 83 protected abstract DecodingState finishDecode(int skippedBytes) 84 throws Exception; 85 }