nio的framework,不需要关注NIO编程的细节,只需要根据几个简单的API就可以使用NIO了.

				/*
				 * Copyright 2004-2006 the original author or authors.
				 *
				 * Licensed 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, software
				 * distributed under the License is distributed on an "AS IS" BASIS,
				 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
				 * See the License for the specific language governing permissions and
				 * limitations under the License.
				 */
				package net.sf.cindy;
				
				/**
				 * Decode Packet to object.
				 * 
				 * @author Roger Chen
				 * @version $id$
				 */
				public interface PacketDecoder {
				
				    /**
				     * Decode packet to object. The content of the packet is readonly, and it's
				     * position will not be changed if the method return null.
				     * 
				     * @param session
				     *            session
				     * @param packet
				     *            packet
				     * @return decoded object
				     * @throws Exception
				     *             any exception
				     */
				    Object decode(Session session, Packet packet) throws Exception;
				
				}