1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 * 19 */ 20 package org.apache.mina.example.sumup.codec; 21 22 import org.apache.mina.core.buffer.IoBuffer; 23 import org.apache.mina.core.session.IoSession; 24 import org.apache.mina.example.sumup.message.AbstractMessage; 25 import org.apache.mina.filter.codec.ProtocolEncoderOutput; 26 import org.apache.mina.filter.codec.demux.MessageEncoder; 27 28 /** 29 * A {@link MessageEncoder} that encodes message header and forwards 30 * the encoding of body to a subclass. 31 * 32 * @author The Apache MINA Project (dev@mina.apache.org) 33 */ 34 public abstract class AbstractMessageEncoder<T extends AbstractMessage> implements MessageEncoder<T> { 35 private final int type; 36 37 protected AbstractMessageEncoder(int type) { 38 this.type = type; 39 } 40 41 public void encode(IoSession session, T message, ProtocolEncoderOutput out) throws Exception { 42 IoBuffer buf = IoBuffer.allocate(16); 43 buf.setAutoExpand(true); // Enable auto-expand for easier encoding 44 45 // Encode a header 46 buf.putShort((short) type); 47 buf.putInt(message.getSequence()); 48 49 // Encode a body 50 encodeBody(session, message, buf); 51 buf.flip(); 52 out.write(buf); 53 } 54 55 protected abstract void encodeBody(IoSession session, T message, IoBuffer out); 56 }