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.handler.demux; 021 022import org.apache.mina.core.session.IoSession; 023 024/** 025 * A handler interface that {@link DemuxingIoHandler} forwards 026 * <tt>messageReceived</tt> or <tt>messageSent</tt> events to. You have to 027 * register your handler with the type of the message you want to get notified 028 * using {@link DemuxingIoHandler#addReceivedMessageHandler(Class, MessageHandler)} 029 * or {@link DemuxingIoHandler#addSentMessageHandler(Class, MessageHandler)}. 030 * 031 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 032 */ 033public interface MessageHandler<E> { 034 /** 035 * A {@link MessageHandler} that does nothing. This is useful when 036 * you want to ignore a message of a specific type silently. 037 */ 038 MessageHandler<Object> NOOP = new MessageHandler<Object>() { 039 public void handleMessage(IoSession session, Object message) { 040 // Do nothing 041 } 042 }; 043 044 /** 045 * Invoked when the specific type of message is received from or sent to 046 * the specified <code>session</code>. 047 * 048 * @param session the associated {@link IoSession} 049 * @param message the message to decode. Its type is set by the implementation 050 * @throws Exception if there is an error during the message processing 051 */ 052 void handleMessage(IoSession session, E message) throws Exception; 053}