View Javadoc
1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.handler.codec.marshalling;
17  
18  import io.netty.buffer.ByteBuf;
19  import io.netty.channel.ChannelHandler.Sharable;
20  import io.netty.channel.ChannelHandlerContext;
21  import io.netty.handler.codec.MessageToByteEncoder;
22  
23  import org.jboss.marshalling.Marshaller;
24  
25  /**
26   * {@link MessageToByteEncoder} implementation which uses JBoss Marshalling to marshal
27   * an Object. Be aware that this encoder is not compatible with an other client that just use
28   * JBoss Marshalling as it includes the size of every {@link Object} that gets serialized in
29   * front of the {@link Object} itself.
30   *
31   * Use this with {@link MarshallingDecoder}
32   *
33   * See <a href="http://www.jboss.org/jbossmarshalling">JBoss Marshalling website</a>
34   * for more informations
35   *
36   */
37  @Sharable
38  public class MarshallingEncoder extends MessageToByteEncoder<Object> {
39  
40      private static final byte[] LENGTH_PLACEHOLDER = new byte[4];
41      private final MarshallerProvider provider;
42  
43      /**
44       * Creates a new encoder.
45       *
46       * @param provider the {@link MarshallerProvider} to use
47       */
48      public MarshallingEncoder(MarshallerProvider provider) {
49          this.provider = provider;
50      }
51  
52      @Override
53      protected void encode(ChannelHandlerContext ctx, Object msg, ByteBuf out) throws Exception {
54          Marshaller marshaller = provider.getMarshaller(ctx);
55          int lengthPos = out.writerIndex();
56          out.writeBytes(LENGTH_PLACEHOLDER);
57          ChannelBufferByteOutput output = new ChannelBufferByteOutput(out);
58          marshaller.start(output);
59          marshaller.writeObject(msg);
60          marshaller.finish();
61          marshaller.close();
62  
63          out.setInt(lengthPos, out.writerIndex() - lengthPos - 4);
64      }
65  }