io.netty.handler.codec.http

Class HttpMessageDecoder

java.lang.Object

io.netty.channel.ChannelStateHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder<O>

io.netty.handler.codec.ReplayingDecoder<Object,HttpMessageDecoder.State>

io.netty.handler.codec.http.HttpMessageDecoder

All Implemented Interfaces:

io.netty.channel.ChannelHandler, io.netty.channel.ChannelInboundByteHandler, io.netty.channel.ChannelInboundHandler, io.netty.channel.ChannelStateHandler

Direct Known Subclasses:

HttpRequestDecoder, HttpResponseDecoder, RtspMessageDecoder

public abstract class HttpMessageDecoder
extends io.netty.handler.codec.ReplayingDecoder<Object,HttpMessageDecoder.State>

Decodes ByteBufs into HttpMessages and HttpChunks.

Parameters that prevents excessive memory consumption

Name	Meaning
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.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected static class	HttpMessageDecoder.State The internal state of HttpMessageDecoder.

Nested classes/interfaces inherited from interface io.netty.channel.ChannelHandler

io.netty.channel.ChannelHandler.Sharable

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	HttpMessageDecoder() Creates a new instance with the default maxInitialLineLength (4096}, maxHeaderSize (8192), and maxChunkSize (8192).
protected	HttpMessageDecoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize) Creates a new instance with the specified parameters.

Method Summary

Methods

Modifier and Type	Method and Description
protected abstract HttpMessage	createMessage(String[] initialLine)
Object	decode(io.netty.channel.ChannelHandlerContext ctx, io.netty.buffer.ByteBuf buffer)
protected boolean	isContentAlwaysEmpty(HttpMessage msg)
protected abstract boolean	isDecodingRequest()

Methods inherited from class io.netty.handler.codec.ReplayingDecoder

actualReadableBytes, callDecode, channelInactive, checkpoint, checkpoint, internalBuffer, newInboundBuffer, state, state

Methods inherited from class io.netty.handler.codec.ByteToMessageDecoder

beforeAdd, decodeLast, inboundBufferUpdated, replace

Methods inherited from class io.netty.channel.ChannelStateHandlerAdapter

afterAdd, afterRemove, beforeRemove, channelActive, channelRegistered, channelUnregistered, exceptionCaught, userEventTriggered

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface io.netty.channel.ChannelStateHandler

channelActive, channelRegistered, channelUnregistered

Methods inherited from interface io.netty.channel.ChannelHandler

afterAdd, afterRemove, beforeRemove, exceptionCaught, userEventTriggered

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

public Object decode(io.netty.channel.ChannelHandlerContext ctx,
            io.netty.buffer.ByteBuf buffer)
              throws Exception

Specified by:

decode in class io.netty.handler.codec.ByteToMessageDecoder<Object>

Throws:

Exception

isContentAlwaysEmpty

protected boolean isContentAlwaysEmpty(HttpMessage msg)

isDecodingRequest

protected abstract boolean isDecodingRequest()

createMessage

protected abstract HttpMessage createMessage(String[] initialLine)
                                      throws Exception

Throws:

Exception