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, LifeCycleAwareChannelHandler

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 |
 +----------+
 

Nested Class Summary

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

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field and Description
private ChannelBuffer[]	delimiters
private boolean	discardingTooLongFrame
private boolean	failFast
private LineBasedFrameDecoder	lineBasedDecoder Set only when decoding with "\n" and "\r\n" as the delimiter.
private int	maxFrameLength
private boolean	stripDelimiter
private int	tooLongFrameLength

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

cumulation, DEFAULT_MAX_COMPOSITEBUFFER_COMPONENTS

Constructor Summary

Constructors

Constructor and Description
DelimiterBasedFrameDecoder(int maxFrameLength, boolean stripDelimiter, boolean failFast, ChannelBuffer... delimiters) Creates a new instance.
DelimiterBasedFrameDecoder(int maxFrameLength, boolean stripDelimiter, boolean failFast, ChannelBuffer delimiter) Creates a new instance.
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

Modifier and Type	Method and Description
protected java.lang.Object	decode(ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer) Decodes the received packets so far into a frame.
private void	fail(ChannelHandlerContext ctx, long frameLength)
private static int	indexOf(ChannelBuffer haystack, ChannelBuffer needle) Returns the number of bytes between the readerIndex of the haystack and the first needle found in the haystack.
private static boolean	isLineBased(ChannelBuffer[] delimiters) Returns true if the delimiters are "\n" and "\r\n".
private boolean	isSubclass() Return true if the current instance is a subclass of DelimiterBasedFrameDecoder
private static void	validateDelimiter(ChannelBuffer delimiter)
private static void	validateMaxFrameLength(int maxFrameLength)

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, newCumulationBuffer, 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 Detail

delimiters

private final ChannelBuffer[] delimiters

maxFrameLength

private final int maxFrameLength

stripDelimiter

private final boolean stripDelimiter

failFast

private final boolean failFast

discardingTooLongFrame

private boolean discardingTooLongFrame

tooLongFrameLength

private int tooLongFrameLength

lineBasedDecoder

private final LineBasedFrameDecoder lineBasedDecoder

Set only when decoding with "\n" and "\r\n" as the delimiter.

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,
                                  boolean stripDelimiter,
                                  boolean failFast,
                                  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

failFast - If true, a TooLongFrameException is thrown as soon as the decoder notices the length of the frame will exceed maxFrameLength regardless of whether the entire frame has been read. If false, a TooLongFrameException is thrown after the entire frame that exceeds maxFrameLength has been read.

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

DelimiterBasedFrameDecoder

public DelimiterBasedFrameDecoder(int maxFrameLength,
                                  boolean stripDelimiter,
                                  boolean failFast,
                                  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

failFast - If true, a TooLongFrameException is thrown as soon as the decoder notices the length of the frame will exceed maxFrameLength regardless of whether the entire frame has been read. If false, a TooLongFrameException is thrown after the entire frame that exceeds maxFrameLength has been read.

delimiters - the delimiters

Method Detail

isLineBased

private static boolean isLineBased(ChannelBuffer[] delimiters)

Returns true if the delimiters are "\n" and "\r\n".

isSubclass

private boolean isSubclass()

Return true if the current instance is a subclass of DelimiterBasedFrameDecoder

decode

protected java.lang.Object decode(ChannelHandlerContext ctx,
                                  Channel channel,
                                  ChannelBuffer buffer)
                           throws java.lang.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:

java.lang.Exception

fail

private void fail(ChannelHandlerContext ctx,
                  long frameLength)

indexOf

private static int indexOf(ChannelBuffer haystack,
                           ChannelBuffer needle)

Returns the number of bytes between the readerIndex of the haystack and the first needle found in the haystack. -1 is returned if no needle is found in the haystack.

validateDelimiter

private static void validateDelimiter(ChannelBuffer delimiter)

validateMaxFrameLength

private static void validateMaxFrameLength(int maxFrameLength)