public class XmlFrameDecoder extends ByteToMessageDecoder
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.
ByteToMessageDecoder.CumulatorChannelHandler.SharableCOMPOSITE_CUMULATOR, MERGE_CUMULATOR| 构造器和说明 |
|---|
XmlFrameDecoder(int maxFrameLength) |
| 限定符和类型 | 方法和说明 |
|---|---|
protected void |
decode(ChannelHandlerContext ctx,
ByteBuf in,
java.util.List<java.lang.Object> out)
Decode the from one
ByteBuf to an other. |
actualReadableBytes, callDecode, channelInactive, channelRead, channelReadComplete, decodeLast, discardSomeReadBytes, handlerRemoved, handlerRemoved0, internalBuffer, isSingleDecode, setCumulator, setDiscardAfterReads, setSingleDecode, userEventTriggeredchannelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaughtensureNotSharable, handlerAdded, isSharableclone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, waithandlerAddedprotected void decode(ChannelHandlerContext ctx, ByteBuf in, java.util.List<java.lang.Object> out) throws java.lang.Exception
ByteToMessageDecoderByteBuf 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.decode 在类中 ByteToMessageDecoderctx - the ChannelHandlerContext which this ByteToMessageDecoder belongs toin - the ByteBuf from which to read dataout - the List to which decoded messages should be addedjava.lang.Exception - is thrown if an error occurs