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 information
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 }