decodingstate.java

来自「mina是以Java实现的一个开源的网络程序框架」· Java 代码 · 共 63 行

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
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 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
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 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
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package org.apache.mina.filter.codec.statemachine;

import org.apache.mina.core.buffer.IoBuffer;
import org.apache.mina.core.session.IoSession;
import org.apache.mina.filter.codec.ProtocolDecoderOutput;

/**
 * Represents a state in a decoder state machine used by 
 * {@link DecodingStateMachine}.
 * 
 * @author The Apache MINA Project ([e-mail])
 * @version $Rev: 671827 $, $Date: 2008-06-26 10:49:48 +0200 (Thu, 26 Jun 2008) $
 */
public interface DecodingState {
    /**
     * Invoked when data is available for this state.
     * 
     * @param in the data to be decoded.
     * @param out used to write decoded objects.
     * @return the next state if a state transition was triggered (use 
     *         <code>this</code> for loop transitions) or <code>null</code> if 
     *         the state machine has reached its end.
     * @throws Exception if the read data violated protocol specification.
     */
    DecodingState decode(IoBuffer in, ProtocolDecoderOutput out)
            throws Exception;
    
    /**
     * Invoked when the associated {@link IoSession} is closed. This method is 
     * useful when you deal with protocols which don't specify the length of a 
     * message (e.g. HTTP responses without <tt>content-length</tt> header). 
     * Implement this method to process the remaining data that 
     * {@link #decode(IoBuffer, ProtocolDecoderOutput)} method didn't process 
     * completely.
     * 
     * @param out used to write decoded objects.
     * @return the next state if a state transition was triggered (use 
     *         <code>this</code> for loop transitions) or <code>null</code> if 
     *         the state machine has reached its end.
     * @throws Exception if the read data violated protocol specification.
     */
    DecodingState finishDecode(ProtocolDecoderOutput out) throws Exception;
}