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

  • Field Details

    • 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 Details

    • 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 Details

    • 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 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 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:
      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)