org.jboss.netty.handler.codec.serialization
Class ObjectDecoder

java.lang.Object
  org.jboss.netty.channel.SimpleChannelUpstreamHandler
      org.jboss.netty.handler.codec.frame.FrameDecoder
          org.jboss.netty.handler.codec.frame.LengthFieldBasedFrameDecoder
              org.jboss.netty.handler.codec.serialization.ObjectDecoder

All Implemented Interfaces:

ChannelHandler, ChannelUpstreamHandler

public class ObjectDecoder
extends LengthFieldBasedFrameDecoder

A decoder which deserializes the received ChannelBuffers into Java objects.

Please note that the serialized form this decoder expects is not compatible with the standard ObjectOutputStream. Please use ObjectEncoder or ObjectEncoderOutputStream to ensure the interoperability with this decoder.

Version:

$Rev: 2279 $, $Date: 2010-05-13 23:13:07 +0900 (Thu, 13 May 2010) $

Author:

The Netty Project, Trustin Lee

Nested Class Summary

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

ChannelHandler.Sharable

Constructor Summary

ObjectDecoder()
Creates a new decoder whose maximum object size is 1048576 bytes.

ObjectDecoder(int maxObjectSize)
Creates a new decoder with the specified maximum object size.

ObjectDecoder(int maxObjectSize, ClassLoader classLoader)
Creates a new decoder with the specified maximum object size.

Method Summary

protected Object	decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) Decodes the received packets so far into a frame.
protected ChannelBuffer	extractFrame(ChannelBuffer buffer, int index, int length) Extract the sub-region of the specified buffer.

Methods inherited from class org.jboss.netty.handler.codec.frame.FrameDecoder

channelClosed, channelDisconnected, decodeLast, exceptionCaught, messageReceived

Methods inherited from class org.jboss.netty.channel.SimpleChannelUpstreamHandler

channelBound, channelConnected, channelInterestChanged, channelOpen, channelUnbound, childChannelClosed, childChannelOpen, handleUpstream, writeComplete

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ObjectDecoder

public ObjectDecoder()

Creates a new decoder whose maximum object size is 1048576 bytes. If the size of the received object is greater than 1048576 bytes, a StreamCorruptedException will be raised.

ObjectDecoder

public ObjectDecoder(int maxObjectSize)

Creates a new decoder with the specified maximum object size.

Parameters:

maxObjectSize - the maximum byte length of the serialized object. if the length of the received object is greater than this value, StreamCorruptedException will be raised.

ObjectDecoder

public ObjectDecoder(int maxObjectSize,
                     ClassLoader classLoader)

Creates a new decoder with the specified maximum object size.

Parameters:

maxObjectSize - the maximum byte length of the serialized object. if the length of the received object is greater than this value, StreamCorruptedException will be raised.

classLoader - the ClassLoader which will load the class of the serialized object

Method Detail

decode

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

Description copied from class: FrameDecoder

Decodes the received packets so far into a frame.

Overrides:

decode in class LengthFieldBasedFrameDecoder

Parameters:

ctx - the context of this handler

channel - the current channel

buffer - the cumulative buffer of received packets so far. Note that the buffer might be empty, which means you should not make an assumption that the buffer contains at least one byte in your decoder implementation.

Returns:

the decoded frame if a full frame was received and decoded. null if there's not enough data in the buffer to decode a frame.

Throws:

Exception

extractFrame

protected ChannelBuffer extractFrame(ChannelBuffer buffer,
                                     int index,
                                     int length)

Description copied from class: LengthFieldBasedFrameDecoder

Extract the sub-region of the specified buffer. This method is called by LengthFieldBasedFrameDecoder.decode(ChannelHandlerContext, Channel, ChannelBuffer) for each frame. The default implementation returns a copy of the sub-region. For example, you could override this method to use an alternative ChannelBufferFactory.

If you are sure that the frame and its content are not accessed after the current LengthFieldBasedFrameDecoder.decode(ChannelHandlerContext, Channel, ChannelBuffer) call returns, you can even avoid memory copy by returning the sliced sub-region (i.e. return buffer.slice(index, length)). It's often useful when you convert the extracted frame into an object. Refer to the source code of ObjectDecoder to see how this method is overridden to avoid memory copy.

Overrides:

extractFrame in class LengthFieldBasedFrameDecoder