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.example.reverser;
021
022import org.apache.mina.core.service.IoHandler;
023import org.apache.mina.core.service.IoHandlerAdapter;
024import org.apache.mina.core.session.IoSession;
025
026/**
027 * {@link IoHandler} implementation of reverser server protocol.
028 *
029 * @author <a href="http://mina.apache.org">Apache MINA Project</a>
030 */
031public class ReverseProtocolHandler extends IoHandlerAdapter {
032    @Override
033    public void exceptionCaught(IoSession session, Throwable cause) {
034        // Close connection when unexpected exception is caught.
035        session.closeNow();
036    }
037
038    @Override
039    public void messageReceived(IoSession session, Object message) {
040        // Reverse reveiced string
041        String str = message.toString();
042        StringBuilder buf = new StringBuilder(str.length());
043        for (int i = str.length() - 1; i >= 0; i--) {
044            buf.append(str.charAt(i));
045        }
046
047        // and write it back.
048        session.write(buf.toString());
049    }
050}