content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You 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 com.alipay.remoting.codec;
  
  import java.io.Serializable;
  
  import com.alipay.remoting.Connection;
  import com.alipay.remoting.Protocol;
  import com.alipay.remoting.ProtocolCode;
  import com.alipay.remoting.ProtocolManager;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.channel.ChannelHandler;
  import io.netty.channel.ChannelHandlerContext;
  import io.netty.handler.codec.MessageToByteEncoder;
  import io.netty.util.Attribute;
  
  /**
   * Protocol code based newEncoder, the main newEncoder for a certain protocol, which is lead by one or multi bytes (magic code).
   *
   * Notice: this is stateless can be noted as {@link io.netty.channel.ChannelHandler.Sharable}
   * @author jiangping
   * @version $Id: ProtocolCodeBasedEncoder.java, v 0.1 2015-12-11 PM 7:30:30 tao Exp $
   */
  @ChannelHandler.Sharable
  public class ProtocolCodeBasedEncoder extends MessageToByteEncoder<Serializable> {
  
      /** default protocol code */
      protected ProtocolCode defaultProtocolCode;
  
      public ProtocolCodeBasedEncoder(ProtocolCode defaultProtocolCode) {
          super();
          this.defaultProtocolCode = defaultProtocolCode;
      }
  
      @Override
      protected void encode(ChannelHandlerContext ctx, Serializable msg, ByteBuf out)
                                                                                     throws Exception {
          Attribute<ProtocolCode> att = ctx.channel().attr(Connection.PROTOCOL);
          ProtocolCode protocolCode;
          if (att == null || att.get() == null) {
              protocolCode = this.defaultProtocolCode;
          } else {
              protocolCode = att.get();
          }
          Protocol protocol = ProtocolManager.getProtocol(protocolCode);
          protocol.getEncoder().encode(ctx, msg, out);
      }
  
  }
  