org.jboss.netty.handler.codec.frame
Class DelimiterBasedFrameDecoder

java.lang.Object
  extended by org.jboss.netty.channel.SimpleChannelHandler
      extended by org.jboss.netty.handler.codec.frame.FrameDecoder
          extended by org.jboss.netty.handler.codec.frame.DelimiterBasedFrameDecoder
All Implemented Interfaces:
ChannelDownstreamHandler, ChannelHandler, ChannelUpstreamHandler

public class DelimiterBasedFrameDecoder
extends FrameDecoder

A FrameDecoder which decodes the received ChannelBuffers into the ChannelBuffers split by one or more delimiters. It is particularly useful for decoding the frames which ends with a delimiter such as NUL or newline characters.

Predefined delimiters

Delimiters defines frequently used delimiters for convenience' sake.

Specifying more than one delimiter

DelimiterBasedFrameDecoder allows you to specify more than one delimiter. If more than one delimiter is found in the buffer, it chooses the delimiter which produces the shortest frame. For example, if you have the following data in the buffer:

 +--------------+
 | ABC\nDEF\r\n |
 +--------------+
 
a DelimiterBasedFrameDecoder(Delimiters.lineDelimiter()) will choose '\n' as the first delimiter and produce two frames:
 +-----+-----+
 | ABC | DEF |
 +-----+-----+
 
rather than incorrectly choosing '\r\n' as the first delimiter:
 +----------+
 | ABC\nDEF |
 +----------+
 

Version:
$Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
Author:
The Netty Project (netty-dev@lists.jboss.org), Trustin Lee (tlee@redhat.com)

Constructor Summary
DelimiterBasedFrameDecoder(int maxFrameLength, ChannelBuffer... delimiters)
          Creates a new instance.
DelimiterBasedFrameDecoder(int maxFrameLength, ChannelBuffer delimiter)
          Creates a new instance.
 
Method Summary
protected  Object decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer)
          Decodes the received packets so far into a frame.
 
Methods inherited from class org.jboss.netty.handler.codec.frame.FrameDecoder
channelClosed, channelDisconnected, decodeLast, exceptionCaught, messageReceived
 
Methods inherited from class org.jboss.netty.channel.SimpleChannelHandler
bindRequested, channelBound, channelConnected, channelInterestChanged, channelOpen, channelUnbound, childChannelClosed, childChannelOpen, closeRequested, connectRequested, disconnectRequested, handleDownstream, handleUpstream, setInterestOpsRequested, unbindRequested, writeRequested
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

DelimiterBasedFrameDecoder

public DelimiterBasedFrameDecoder(int maxFrameLength,
                                  ChannelBuffer delimiter)
Creates a new instance.

Parameters:
maxFrameLength - the maximum length of the decoded frame. A TooLongFrameException is thrown if the length of the frame exceeds this value.
delimiter - the delimiter

DelimiterBasedFrameDecoder

public DelimiterBasedFrameDecoder(int maxFrameLength,
                                  ChannelBuffer... delimiters)
Creates a new instance.

Parameters:
maxFrameLength - the maximum length of the decoded frame. A TooLongFrameException is thrown if the length of the frame exceeds this value.
delimiters - the delimiters
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.

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
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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