Package org.jboss.netty.handler.codec.frame

Class FixedLengthFrameDecoder

java.lang.Object

org.jboss.netty.channel.SimpleChannelUpstreamHandler

org.jboss.netty.handler.codec.frame.FrameDecoder

org.jboss.netty.handler.codec.frame.FixedLengthFrameDecoder

All Implemented Interfaces:

ChannelHandler, ChannelUpstreamHandler, LifeCycleAwareChannelHandler

public class FixedLengthFrameDecoder
extends FrameDecoder

A decoder that splits the received ChannelBuffers by the fixed number of bytes. For example, if you received the following four fragmented packets:

 +---+----+------+----+
 | A | BC | DEFG | HI |
 +---+----+------+----+
 

A FixedLengthFrameDecoder(3) will decode them into the following three packets with the fixed length:

 +-----+-----+-----+
 | ABC | DEF | GHI |
 +-----+-----+-----+
 

Nested Class Summary

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

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field	Description
private final boolean	allocateFullBuffer
private final int	frameLength

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

cumulation, DEFAULT_MAX_COMPOSITEBUFFER_COMPONENTS

Constructor Summary

Constructors

Constructor	Description
FixedLengthFrameDecoder(int frameLength)	Calls FixedLengthFrameDecoder(int, boolean) with false
FixedLengthFrameDecoder(int frameLength, boolean allocateFullBuffer)	Creates a new instance.

Method Summary

Modifier and Type	Method	Description
protected Object	decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer)	Decodes the received packets so far into a frame.
protected ChannelBuffer	newCumulationBuffer(ChannelHandlerContext ctx, int minimumCapacity)	Create a new ChannelBuffer which is used for the cumulation.

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

actualReadableBytes, afterAdd, afterRemove, appendToCumulation, beforeAdd, beforeRemove, channelClosed, channelDisconnected, cleanup, decodeLast, exceptionCaught, extractFrame, getMaxCumulationBufferCapacity, getMaxCumulationBufferComponents, internalBuffer, isUnfold, messageReceived, replace, setMaxCumulationBufferCapacity, setMaxCumulationBufferComponents, setUnfold, unfoldAndFireMessageReceived, updateCumulation

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

Field Details

frameLength

private final int frameLength

allocateFullBuffer

private final boolean allocateFullBuffer

Constructor Details

FixedLengthFrameDecoder

public FixedLengthFrameDecoder(int frameLength)

Calls FixedLengthFrameDecoder(int, boolean) with false

FixedLengthFrameDecoder

public FixedLengthFrameDecoder(int frameLength,
 boolean allocateFullBuffer)

Creates a new instance.

Parameters:

frameLength - the length of the frame

allocateFullBuffer - true if the cumulative ChannelBuffer should use the frameLength as its initial size

Method Details

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. If an sub-class wants to extract a frame out of the buffer it should use the FrameDecoder.extractFrame(ChannelBuffer, int, int) method, to make optimizations easier later.

Specified by:

decode in class FrameDecoder

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

newCumulationBuffer

protected ChannelBuffer newCumulationBuffer(ChannelHandlerContext ctx,
 int minimumCapacity)

Description copied from class: FrameDecoder

Create a new ChannelBuffer which is used for the cumulation. Sub-classes may override this.

Overrides:

newCumulationBuffer in class FrameDecoder

Parameters:

ctx - ChannelHandlerContext for this handler

Returns:

buffer the ChannelBuffer which is used for cumulation