## org.jboss.netty.handler.codec.protobuf
Class ProtobufVarint32LengthFieldPrepender

    java.lang.Object
      org.jboss.netty.handler.codec.oneone.OneToOneEncoder
          org.jboss.netty.handler.codec.protobuf.ProtobufVarint32LengthFieldPrepender

All Implemented Interfaces:
  ChannelDownstreamHandler, ChannelHandler

    @ChannelHandler.Sharable
    public class ProtobufVarint32LengthFieldPrepender

extends OneToOneEncoder

An encoder that prepends the the Google Protocol Buffers Base 128 Varints integer length field. For example:

     BEFORE DECODE (300 bytes)       AFTER DECODE (302 bytes)
     +---------------+               +--------+---------------+
     | Protobuf Data |-------------->| Length | Protobuf Data |
     |  (300 bytes)  |               | 0xAC02 |  (300 bytes)  |
     +---------------+               +--------+---------------+

*

Version:
  $Rev: 2315 $, $Date: 2010-06-23 14:16:47 +0900 (Wed, 23 Jun 2010) $
Author:
  The Netty Project, Tomasz Blachowicz (tblachowicz@gmail.com), Trustin Lee
See Also:
  `CodedOutputStream`

Nested Class Summary

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

Constructor Summary
`ProtobufVarint32LengthFieldPrepender()` Creates a new instance.

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

Methods inherited from class org.jboss.netty.handler.codec.oneone.OneToOneEncoder
`handleDownstream`

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

Constructor Detail

### ProtobufVarint32LengthFieldPrepender

    public ProtobufVarint32LengthFieldPrepender()

  Creates a new instance.

Method Detail

### encode

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

  Description copied from class: `OneToOneEncoder`
  Transforms the specified message into another message and return the transformed message. Note that you can not return `null`, unlike you can in `OneToOneDecoder.decode(ChannelHandlerContext, Channel, Object)`; you must return something, at least `ChannelBuffers.EMPTY_BUFFER`.

  Specified by:
    `encode` in class `OneToOneEncoder`
  Throws:
    `Exception`

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