Package io.netty.handler.codec.xml

Class XmlFrameDecoder

  • All Implemented Interfaces:
    io.netty.channel.ChannelHandler, io.netty.channel.ChannelInboundHandler
    public class XmlFrameDecoder
extends ByteToMessageDecoder
    A frame decoder for single separate XML based message streams.

    A couple examples will better help illustrate what this decoder actually does.

    Given an input array of bytes split over 3 frames like this: 

     +-----+-----+-----------+
 | <an | Xml | Element/> |
 +-----+-----+-----------+

    this decoder would output a single frame: 

     +-----------------+
 | <anXmlElement/> |
 +-----------------+
    Given an input array of bytes split over 5 frames like this: 
     +-----+-----+-----------+-----+----------------------------------+
 | <an | Xml | Element/> | <ro | ot><child>content</child></root> |
 +-----+-----+-----------+-----+----------------------------------+

    this decoder would output two frames: 

     +-----------------+-------------------------------------+
 | <anXmlElement/> | <root><child>content</child></root> |
 +-----------------+-------------------------------------+

    The byte stream is expected to be in UTF-8 character encoding or ASCII. The current implementation uses direct byte to char cast and then compares that char to a few low range ASCII characters like '<', '>' or '/'. UTF-8 is not using low range [0..0x7F] byte values for multibyte codepoint representations therefore fully supported by this implementation.

    Please note that this decoder is not suitable for xml streaming protocols such as XMPP, where an initial xml element opens the stream and only gets closed at the end of the session, although this class could probably allow for such type of message flow with minor modifications.

    • Constructor Detail

      • XmlFrameDecoder

        public XmlFrameDecoder​(int maxFrameLength)

    • Method Detail

      • decode

        protected void decode​(io.netty.channel.ChannelHandlerContext ctx,
                      io.netty.buffer.ByteBuf in,
                      List<Object> out)
               throws 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:
        Exception - is thrown if an error occurs