Class FixedLengthFrameDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder

io.netty.handler.codec.FixedLengthFrameDecoder

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler

public class FixedLengthFrameDecoder
extends ByteToMessageDecoder

A decoder that splits the received ByteBufs 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 class ByteToMessageDecoder

ByteToMessageDecoder.Cumulator

Nested classes/interfaces inherited from interface ChannelHandler

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field	Description
private final int	frameLength

Fields inherited from class ByteToMessageDecoder

COMPOSITE_CUMULATOR, cumulation, MERGE_CUMULATOR

Constructor Summary

Constructors

Constructor	Description
FixedLengthFrameDecoder(int frameLength)	Creates a new instance.

Method Summary

Modifier and Type	Method	Description
protected java.lang.Object	decode(ChannelHandlerContext ctx, ByteBuf in)	Create a frame out of the ByteBuf and return it.
protected final void	decode(ChannelHandlerContext ctx, ByteBuf in, java.util.List<java.lang.Object> out)	Decode the from one ByteBuf to an other.

Methods inherited from class ByteToMessageDecoder

actualReadableBytes, callDecode, channelInactive, channelInputClosed, channelRead, channelReadComplete, decodeLast, decodeRemovalReentryProtection, discardSomeReadBytes, expandCumulation, fireChannelRead, fireChannelRead, handlerRemoved, handlerRemoved0, internalBuffer, isSingleDecode, setCumulator, setDiscardAfterReads, setSingleDecode, userEventTriggered

Methods inherited from class ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught

Methods inherited from class ChannelHandlerAdapter

ensureNotSharable, handlerAdded, isSharable

Methods inherited from class java.lang.Object

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

Methods inherited from interface ChannelHandler

handlerAdded

Field Details

frameLength

private final int frameLength

Constructor Details

FixedLengthFrameDecoder

public FixedLengthFrameDecoder(int frameLength)

Creates a new instance.

Parameters:

frameLength - the length of the frame

Method Details

decode

protected final void decode(ChannelHandlerContext ctx,
 ByteBuf in,
 java.util.List<java.lang.Object> out)
                     throws java.lang.Exception

Description copied from class: ByteToMessageDecoder

Decode the from one ByteBuf to an other. This method will be called till either the input ByteBuf has nothing to read when return from this method or till nothing was read from the input ByteBuf.

Specified by:

decode in class ByteToMessageDecoder

Parameters:

ctx - the ChannelHandlerContext which this ByteToMessageDecoder belongs to

in - the ByteBuf from which to read data

out - the List to which decoded messages should be added

Throws:

java.lang.Exception - is thrown if an error occurs

decode

protected java.lang.Object decode(ChannelHandlerContext ctx,
 ByteBuf in)
                           throws java.lang.Exception

Create a frame out of the ByteBuf and return it.

Parameters:

ctx - the ChannelHandlerContext which this ByteToMessageDecoder belongs to

in - the ByteBuf from which to read data

Returns:

frame the ByteBuf which represent the frame or null if no frame could be created.

Throws:

java.lang.Exception