Package org.jboss.netty.handler.codec.http

Class HttpMessageDecoder

  • All Implemented Interfaces:
    ChannelHandler, ChannelUpstreamHandler, LifeCycleAwareChannelHandler
    Direct Known Subclasses:
    HttpRequestDecoder, HttpResponseDecoder, RtspMessageDecoder
    public abstract class HttpMessageDecoder
extends ReplayingDecoder<HttpMessageDecoder.State>
    Decodes ChannelBuffers into HttpMessages and HttpChunks.

    Parameters that prevents excessive memory consumption

    NameMeaning
    maxInitialLineLength The maximum length of the initial line (e.g. "GET / HTTP/1.0" or "HTTP/1.0 200 OK") If the length of the initial line exceeds this value, a TooLongFrameException will be raised.
    maxHeaderSize The maximum length of all headers. If the sum of the length of each header exceeds this value, a TooLongFrameException will be raised.
    maxChunkSize The maximum length of the content or each chunk. If the content length (or the length of each chunk) exceeds this value, the content or chunk will be split into multiple HttpChunks whose length is maxChunkSize at maximum.

    Chunked Content

    If the content of an HTTP message is greater than maxChunkSize or the transfer encoding of the HTTP message is 'chunked', this decoder generates one HttpMessage instance and its following HttpChunks per single HTTP message to avoid excessive memory consumption. For example, the following HTTP message: 
     GET / HTTP/1.1
 Transfer-Encoding: chunked

 1a
 abcdefghijklmnopqrstuvwxyz
 10
 1234567890abcdef
 0
 Content-MD5: ...
 [blank line]
    triggers HttpRequestDecoder to generate 4 objects:
    1. An HttpRequest whose chunked property is true,
    2. The first HttpChunk whose content is 'abcdefghijklmnopqrstuvwxyz',
    3. The second HttpChunk whose content is '1234567890abcdef', and
    4. An HttpChunkTrailer which marks the end of the content.
    If you prefer not to handle HttpChunks by yourself for your convenience, insert HttpChunkAggregator after this decoder in the ChannelPipeline. However, please note that your server might not be as memory efficient as without the aggregator.

    Extensibility

    Please note that this decoder is designed to be extended to implement a protocol derived from HTTP, such as RTSP and ICAP. To implement the decoder of such a derived protocol, extend this class and implement all abstract methods properly.

    • Field Detail

      • maxInitialLineLength

        private final int maxInitialLineLength

      • maxHeaderSize

        private final int maxHeaderSize

      • maxChunkSize

        private final int maxChunkSize

      • chunkSize

        private long chunkSize

      • headerSize

        private int headerSize

      • contentRead

        private int contentRead

    • Constructor Detail

      • HttpMessageDecoder

        protected HttpMessageDecoder()
        Creates a new instance with the default maxInitialLineLength (4096}, maxHeaderSize (8192), and maxChunkSize (8192).

      • HttpMessageDecoder

        protected HttpMessageDecoder​(int maxInitialLineLength,
                             int maxHeaderSize,
                             int maxChunkSize)
        Creates a new instance with the specified parameters.

    • Method Detail

      • decode

        protected java.lang.Object decode​(ChannelHandlerContext ctx,
                                  Channel channel,
                                  ChannelBuffer buffer,
                                  HttpMessageDecoder.State state)
                           throws java.lang.Exception
        Description copied from class: ReplayingDecoder
        Decodes the received packets so far into a frame.
        Specified by:
        decode in class ReplayingDecoder<HttpMessageDecoder.State>
        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.
        state - the current decoder state (null if unused)
        Returns:
        the decoded frame
        Throws:
        java.lang.Exception

      • isContentAlwaysEmpty

        protected boolean isContentAlwaysEmpty​(HttpMessage msg)

      • reset

        private java.lang.Object reset()

      • resetState

        private void resetState()

      • skipControlCharacters

        private static void skipControlCharacters​(ChannelBuffer buffer)

      • readFixedLengthContent

        private java.lang.Object readFixedLengthContent​(ChannelBuffer buffer)

      • isDecodingRequest

        protected abstract boolean isDecodingRequest()

      • createMessage

        protected abstract HttpMessage createMessage​(java.lang.String[] initialLine)
                                      throws java.lang.Exception
        Throws:
        java.lang.Exception

      • getChunkSize

        private static int getChunkSize​(java.lang.String hex)

      • splitInitialLine

        private static java.lang.String[] splitInitialLine​(java.lang.String sb)

      • splitHeader

        private static java.lang.String[] splitHeader​(java.lang.String sb)

      • findNonWhitespace

        private static int findNonWhitespace​(java.lang.String sb,
                                     int offset)

      • findWhitespace

        private static int findWhitespace​(java.lang.String sb,
                                  int offset)

      • findEndOfString

        private static int findEndOfString​(java.lang.String sb)