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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.codec.delimited;
21  
22  import java.nio.ByteBuffer;
23  
24  import org.apache.mina.codec.StatelessProtocolEncoder;
25  
26  /**
27   * 
28   * @author <a href="http://mina.apache.org">Apache MINA Project</a>
29   */
30  public class SizePrefixedEncoder<IN> implements StatelessProtocolEncoder<IN, ByteBuffer> {
31  
32      private final ByteBufferEncoder<Integer> sizeEncoder;
33  
34      private final ByteBufferEncoder<IN> payloadEncoder;
35  
36      public SizePrefixedEncoder(ByteBufferEncoder<Integer> sizeEncoder, ByteBufferEncoder<IN> payloadEncoder) {
37          super();
38          this.sizeEncoder = sizeEncoder;
39          this.payloadEncoder = payloadEncoder;
40      }
41  
42      @Override
43      public Void createEncoderState() {
44          // stateless!
45          return null;
46      }
47  
48      @Override
49      public ByteBuffer encode(IN message, Void context) {
50          int messageSize = payloadEncoder.getEncodedSize(message);
51          ByteBuffer buffer = ByteBuffer.allocate(sizeEncoder.getEncodedSize(messageSize) + messageSize);
52  
53          sizeEncoder.writeTo(messageSize, buffer);
54          payloadEncoder.writeTo(message, buffer);
55  
56          buffer.flip();
57          return buffer;
58      }
59  
60  }