io.netty.handler.codec.http

Class HttpObjectDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder

io.netty.handler.codec.http.HttpObjectDecoder

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler

Direct Known Subclasses:

HttpRequestDecoder, HttpResponseDecoder, RtspDecoder, RtspObjectDecoder

public abstract class HttpObjectDecoder
extends ByteToMessageDecoder

Decodes ByteBufs into HttpMessages and HttpContents.

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 HttpContents 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 HttpContents 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 3 objects:

1. An HttpRequest,
2. The first HttpContent whose content is 'abcdefghijklmnopqrstuvwxyz',
3. The second LastHttpContent whose content is '1234567890abcdef', which marks the end of the content.

If you prefer not to handle HttpContents by yourself for your convenience, insert HttpObjectAggregator 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/interfaces inherited from class io.netty.handler.codec.ByteToMessageDecoder

ByteToMessageDecoder.Cumulator

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

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field and Description
protected boolean	validateHeaders

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

COMPOSITE_CUMULATOR, MERGE_CUMULATOR

Constructor Summary

Constructors

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

Method Summary

Modifier and Type	Method and Description
protected abstract HttpMessage	createInvalidMessage()
protected abstract HttpMessage	createMessage(String[] initialLine)
protected void	decode(ChannelHandlerContext ctx, ByteBuf buffer, List<Object> out) Decode the from one ByteBuf to an other.
protected void	decodeLast(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) Is called one last time when the ChannelHandlerContext goes in-active.
protected boolean	isContentAlwaysEmpty(HttpMessage msg)
protected abstract boolean	isDecodingRequest()
void	reset() Resets the state of the decoder so that it is ready to decode a new message.
void	userEventTriggered(ChannelHandlerContext ctx, Object evt) Calls ChannelHandlerContext.fireUserEventTriggered(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline.

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

actualReadableBytes, callDecode, channelInactive, channelRead, channelReadComplete, discardSomeReadBytes, handlerRemoved, handlerRemoved0, internalBuffer, isSingleDecode, setCumulator, setDiscardAfterReads, setSingleDecode

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, handlerAdded, isSharable

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.ChannelHandler

handlerAdded

Field Detail

validateHeaders

protected final boolean validateHeaders

Constructor Detail

HttpObjectDecoder

protected HttpObjectDecoder()

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

HttpObjectDecoder

protected HttpObjectDecoder(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported)

Creates a new instance with the specified parameters.

HttpObjectDecoder

protected HttpObjectDecoder(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported,
                            boolean validateHeaders)

Creates a new instance with the specified parameters.

HttpObjectDecoder

protected HttpObjectDecoder(int maxInitialLineLength,
                            int maxHeaderSize,
                            int maxChunkSize,
                            boolean chunkedSupported,
                            boolean validateHeaders,
                            int initialBufferSize)

Method Detail

decode

protected void decode(ChannelHandlerContext ctx,
                      ByteBuf buffer,
                      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

buffer - 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

decodeLast

protected void decodeLast(ChannelHandlerContext ctx,
                          ByteBuf in,
                          List<Object> out)
                   throws Exception

Description copied from class: ByteToMessageDecoder

Is called one last time when the ChannelHandlerContext goes in-active. Which means the ByteToMessageDecoder.channelInactive(ChannelHandlerContext) was triggered. By default this will just call ByteToMessageDecoder.decode(ChannelHandlerContext, ByteBuf, List) but sub-classes may override this for some special cleanup operation.

Overrides:

decodeLast in class ByteToMessageDecoder

Throws:

Exception

userEventTriggered

public void userEventTriggered(ChannelHandlerContext ctx,
                               Object evt)
                        throws Exception

Description copied from class: ChannelInboundHandlerAdapter

Calls ChannelHandlerContext.fireUserEventTriggered(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

userEventTriggered in interface ChannelInboundHandler

Overrides:

userEventTriggered in class ByteToMessageDecoder

Throws:

Exception

isContentAlwaysEmpty

protected boolean isContentAlwaysEmpty(HttpMessage msg)

reset

public void reset()

Resets the state of the decoder so that it is ready to decode a new message. This method is useful for handling a rejected request with Expect: 100-continue header.

isDecodingRequest

protected abstract boolean isDecodingRequest()

createMessage

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

Throws:

Exception

createInvalidMessage

protected abstract HttpMessage createInvalidMessage()