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    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.common.ByteBuffer;
    23  import org.apache.mina.common.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 Directory Project (mina-dev@directory.apache.org)
    33   * @version $Rev: 555855 $, $Date: 2007-07-13 05:19:00 +0200 (Fri, 13 Jul 2007) $
    34   */
    35  public abstract class AbstractMessageEncoder implements MessageEncoder {
    36      private final int type;
    37
    38      protected AbstractMessageEncoder(int type) {
    39          this.type = type;
    40      }
    41
    42      public void encode(IoSession session, Object message,
    43              ProtocolEncoderOutput out) throws Exception {
    44          AbstractMessage m = (AbstractMessage) message;
    45          ByteBuffer buf = ByteBuffer.allocate(16);
    46          buf.setAutoExpand(true); // Enable auto-expand for easier encoding
    47
    48          // Encode a header
    49          buf.putShort((short) type);
    50          buf.putInt(m.getSequence());
    51
    52          // Encode a body
    53          encodeBody(session, m, buf);
    54          buf.flip();
    55          out.write(buf);
    56      }
    57
    58      protected abstract void encodeBody(IoSession session,
    59              AbstractMessage message, ByteBuffer out);
    60  }