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.sumup.codec; 021 022import org.apache.mina.core.buffer.IoBuffer; 023import org.apache.mina.core.session.IoSession; 024import org.apache.mina.example.sumup.message.AbstractMessage; 025import org.apache.mina.filter.codec.ProtocolEncoderOutput; 026import org.apache.mina.filter.codec.demux.MessageEncoder; 027 028/** 029 * A {@link MessageEncoder} that encodes message header and forwards 030 * the encoding of body to a subclass. 031 * 032 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 033 */ 034public abstract class AbstractMessageEncoder<T extends AbstractMessage> implements MessageEncoder<T> { 035 private final int type; 036 037 protected AbstractMessageEncoder(int type) { 038 this.type = type; 039 } 040 041 public void encode(IoSession session, T message, ProtocolEncoderOutput out) throws Exception { 042 IoBuffer buf = IoBuffer.allocate(16); 043 buf.setAutoExpand(true); // Enable auto-expand for easier encoding 044 045 // Encode a header 046 buf.putShort((short) type); 047 buf.putInt(message.getSequence()); 048 049 // Encode a body 050 encodeBody(session, message, buf); 051 buf.flip(); 052 out.write(buf); 053 } 054 055 protected abstract void encodeBody(IoSession session, T message, IoBuffer out); 056}