## org.jboss.netty.handler.codec.protobuf
Class ProtobufDecoder

    java.lang.Object
      org.jboss.netty.handler.codec.oneone.OneToOneDecoder
          org.jboss.netty.handler.codec.protobuf.ProtobufDecoder

All Implemented Interfaces:
  ChannelHandler, ChannelUpstreamHandler

    @ChannelHandler.Sharable
    public class ProtobufDecoder

extends OneToOneDecoder

Decodes a received `ChannelBuffer` into a Google Protocol Buffers `Message` and `MessageLite`. Please note that this decoder must be used with a proper `FrameDecoder` such as `ProtobufVarint32FrameDecoder` or `LengthFieldBasedFrameDecoder` if you are using a stream-based transport such as TCP/IP. A typical setup for TCP/IP would be:

     ChannelPipeline pipeline = ...;

     // Decoders
     pipeline.addLast("frameDecoder",
                      new LengthFieldBasedFrameDecoder(1048576, 0, 4, 0, 4));
     pipeline.addLast("protobufDecoder",
                      new ProtobufDecoder(MyMessage.getDefaultInstance()));

     // Encoder
     pipeline.addLast("frameEncoder", new LengthFieldPrepender(4));
     pipeline.addLast("protobufEncoder", new ProtobufEncoder());

and then you can use a `MyMessage` instead of a `ChannelBuffer` as a message:

     void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
         MyMessage req = (MyMessage) e.getMessage();
         MyMessage res = MyMessage.newBuilder().setText(
                                   "Did you say '" + req.getText() + "'?").build();
         ch.write(res);
     }

Version:
  $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
Author:
  The Netty Project, Trustin Lee

Nested Class Summary

Nested classes/interfaces inherited from interface org.jboss.netty.channel.ChannelHandler
`ChannelHandler.Sharable`

Constructor Summary
`ProtobufDecoder(MessageLite prototype)` Creates a new instance.
`ProtobufDecoder(MessageLite prototype, ExtensionRegistry extensionRegistry)`

Method Summary
`protected Object` `decode(ChannelHandlerContext ctx, Channel channel, Object msg)` Transforms the specified received message into another message and return the transformed message.

Methods inherited from class org.jboss.netty.handler.codec.oneone.OneToOneDecoder
`handleUpstream`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### ProtobufDecoder

    public ProtobufDecoder(MessageLite prototype)

  Creates a new instance.

### ProtobufDecoder

    public ProtobufDecoder(MessageLite prototype,
                           ExtensionRegistry extensionRegistry)

Method Detail

### decode

    protected Object decode(ChannelHandlerContext ctx,
                            Channel channel,
                            Object msg)
                     throws Exception

  Description copied from class: `OneToOneDecoder`
  Transforms the specified received message into another message and return the transformed message. Return `null` if the received message is supposed to be discarded.

  Specified by:
    `decode` in class `OneToOneDecoder`
  Throws:
    `Exception`

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