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

java.lang.Object
  org.jboss.netty.channel.SimpleChannelUpstreamHandler
      org.jboss.netty.handler.codec.frame.FrameDecoder
          org.jboss.netty.handler.codec.frame.DelimiterBasedFrameDecoder

All Implemented Interfaces:

ChannelHandler, ChannelUpstreamHandler

public class DelimiterBasedFrameDecoder
extends FrameDecoder

A decoder that splits the received ChannelBuffers 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, Trustin Lee

Nested Class Summary

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

ChannelHandler.Sharable

Constructor Summary

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

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

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.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

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,
                                  boolean stripDelimiter,
                                  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.

stripDelimiter - whether the decoded frame should strip out the delimiter or not

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

DelimiterBasedFrameDecoder

public DelimiterBasedFrameDecoder(int maxFrameLength,
                                  boolean stripDelimiter,
                                  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.

stripDelimiter - whether the decoded frame should strip out the delimiter or not

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. 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