transition.java

mina是以Java实现的一个开源的网络程序框架

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package org.apache.mina.statemachine.transition;

import org.apache.mina.statemachine.State;
import org.apache.mina.statemachine.StateMachine;
import org.apache.mina.statemachine.event.Event;

/**
 * The interface implemented by classes which need to react on transitions
 * between states.
 *
 * @author The Apache MINA Project ([e-mail])
 * @version $Rev: 586695 $, $Date: 2007-10-20 12:01:17 +0200 (Sat, 20 Oct 2007) $
 */
public interface Transition {
    /**
     * Executes this {@link Transition}. It is the responsibility of this
     * {@link Transition} to determine whether it actually applies for the
     * specified {@link Event}. If this {@link Transition} doesn't apply
     * nothing should be executed and <code>false</code> must be returned.
     * 
     * @param event the current {@link Event}.
     * @return <code>true</code> if the {@link Transition} was executed, 
     *         <code>false</code> otherwise.
     */
    boolean execute(Event event);
    
    /**
     * Returns the {@link State} which the {@link StateMachine} should move to 
     * if this {@link Transition} is taken and {@link #execute(Event)} returns
     * <code>true</code>.
     * 
     * @return the next {@link State} or <code>null</code> if this 
     *         {@link Transition} is a loopback {@link Transition}.
     */
    State getNextState();
}