Class FixedLengthFrameDecoder
- java.lang.Object
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- org.jboss.netty.channel.SimpleChannelUpstreamHandler
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- org.jboss.netty.handler.codec.frame.FrameDecoder
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- org.jboss.netty.handler.codec.frame.FixedLengthFrameDecoder
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- All Implemented Interfaces:
ChannelHandler
,ChannelUpstreamHandler
,LifeCycleAwareChannelHandler
public class FixedLengthFrameDecoder extends FrameDecoder
A decoder that splits the receivedChannelBuffer
s by the fixed number of bytes. For example, if you received the following four fragmented packets:+---+----+------+----+ | A | BC | DEFG | HI | +---+----+------+----+
AFixedLengthFrameDecoder
(3)
will decode them into the following three packets with the fixed length:+-----+-----+-----+ | ABC | DEF | GHI | +-----+-----+-----+
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Nested Class Summary
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Nested classes/interfaces inherited from interface org.jboss.netty.channel.ChannelHandler
ChannelHandler.Sharable
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Field Summary
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Fields inherited from class org.jboss.netty.handler.codec.frame.FrameDecoder
cumulation, DEFAULT_MAX_COMPOSITEBUFFER_COMPONENTS
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Constructor Summary
Constructors Constructor Description FixedLengthFrameDecoder(int frameLength)
CallsFixedLengthFrameDecoder(int, boolean)
withfalse
FixedLengthFrameDecoder(int frameLength, boolean allocateFullBuffer)
Creates a new instance.
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Method Summary
All Methods Instance Methods Concrete Methods 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 newChannelBuffer
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
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Methods inherited from class org.jboss.netty.channel.SimpleChannelUpstreamHandler
channelBound, channelConnected, channelInterestChanged, channelOpen, channelUnbound, childChannelClosed, childChannelOpen, handleUpstream, writeComplete
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Constructor Detail
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FixedLengthFrameDecoder
public FixedLengthFrameDecoder(int frameLength)
CallsFixedLengthFrameDecoder(int, boolean)
withfalse
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FixedLengthFrameDecoder
public FixedLengthFrameDecoder(int frameLength, boolean allocateFullBuffer)
Creates a new instance.- Parameters:
frameLength
- the length of the frameallocateFullBuffer
-true
if the cumulativeChannelBuffer
should use theframeLength
as its initial size
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Method Detail
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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 theFrameDecoder.extractFrame(ChannelBuffer, int, int)
method, to make optimizations easier later.- Specified by:
decode
in classFrameDecoder
- Parameters:
ctx
- the context of this handlerchannel
- the current channelbuffer
- 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
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newCumulationBuffer
protected ChannelBuffer newCumulationBuffer(ChannelHandlerContext ctx, int minimumCapacity)
Description copied from class:FrameDecoder
Create a newChannelBuffer
which is used for the cumulation. Sub-classes may override this.- Overrides:
newCumulationBuffer
in classFrameDecoder
- Parameters:
ctx
-ChannelHandlerContext
for this handler- Returns:
- buffer the
ChannelBuffer
which is used for cumulation
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