Class JsonObjectDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder

io.netty.handler.codec.json.JsonObjectDecoder

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler

public class JsonObjectDecoder
extends ByteToMessageDecoder

Splits a byte stream of JSON objects and arrays into individual objects/arrays and passes them up the ChannelPipeline.

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 invalid input: '{@code '{'}, {@code '['} or {@code '"'}. UTF-8 is not using low range [0..0x7F] byte values for multibyte codepoint representations therefore fully supported by this implementation. <p> This class does not do any real parsing or validation. A sequence of bytes is considered a JSON object/array if it contains a matching number of opening and closing braces/brackets. It's up to a subsequent {@link ChannelHandler} to parse the JSON text into a more usable form i.e. a POJO.'

Nested Class Summary

Nested classes/interfaces inherited from class ByteToMessageDecoder

ByteToMessageDecoder.Cumulator

Modifier and Type	Class	Description
static interface	ByteToMessageDecoder.Cumulator	Cumulate ByteBufs.

Nested classes/interfaces inherited from interface ChannelHandler

ChannelHandler.Sharable

Modifier and Type	Interface	Description
static @interface	ChannelHandler.Sharable	Indicates that the same instance of the annotated ChannelHandler can be added to one or more ChannelPipelines multiple times without a race condition.

Field Summary

Fields inherited from class ByteToMessageDecoder

COMPOSITE_CUMULATOR, MERGE_CUMULATOR

Modifier and Type	Field	Description
static final ByteToMessageDecoder.Cumulator	COMPOSITE_CUMULATOR	Cumulate ByteBufs by add them to a CompositeByteBuf and so do no memory copy whenever possible.
static final ByteToMessageDecoder.Cumulator	MERGE_CUMULATOR	Cumulate ByteBufs by merge them into one ByteBuf's, using memory copies.

Constructor Summary

Constructors

Constructor	Description
JsonObjectDecoder()
JsonObjectDecoder(boolean streamArrayElements)
JsonObjectDecoder(int maxObjectLength)
JsonObjectDecoder(int maxObjectLength, boolean streamArrayElements)

Method Summary

Modifier and Type	Method	Description
protected void	decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out)	Decode the from one ByteBuf to an other.
protected ByteBuf	extractObject(ChannelHandlerContext ctx, ByteBuf buffer, int index, int length)	Override this method if you want to filter the json objects/arrays that get passed through the pipeline.

Methods inherited from class ByteToMessageDecoder

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

Modifier and Type	Method	Description
protected int	actualReadableBytes()	Returns the actual number of readable bytes in the internal cumulative buffer of this decoder.
protected void	callDecode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out)	Called once data should be decoded from the given ByteBuf.
void	channelInactive(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelInactive() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	channelRead(ChannelHandlerContext ctx, Object input)	Calls ChannelHandlerContext.fireChannelRead(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	channelReadComplete(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelReadComplete() to forward to the next ChannelInboundHandler in the ChannelPipeline.
protected void	decodeLast(ChannelHandlerContext ctx, ByteBuf in, List<Object> out)	Is called one last time when the ChannelHandlerContext goes in-active.
protected final void	discardSomeReadBytes()
final void	handlerRemoved(ChannelHandlerContext ctx)	Do nothing by default, sub-classes may override this method.
protected void	handlerRemoved0(ChannelHandlerContext ctx)	Gets called after the ByteToMessageDecoder was removed from the actual context and it doesn't handle events anymore.
protected ByteBuf	internalBuffer()	Returns the internal cumulative buffer of this decoder.
boolean	isSingleDecode()	If true then only one message is decoded on each ByteToMessageDecoder.channelRead(ChannelHandlerContext, Object) call.
void	setCumulator(ByteToMessageDecoder.Cumulator cumulator)	Set the ByteToMessageDecoder.Cumulator to use for cumulate the received ByteBufs.
void	setDiscardAfterReads(int discardAfterReads)	Set the number of reads after which ByteBuf.discardSomeReadBytes() are called and so free up memory.
void	setSingleDecode(boolean singleDecode)	If set then only one message is decoded on each ByteToMessageDecoder.channelRead(ChannelHandlerContext, Object) call.
void	userEventTriggered(ChannelHandlerContext ctx, Object evt)	Calls ChannelHandlerContext.fireUserEventTriggered(Object) to forward to the next ChannelInboundHandler in the ChannelPipeline.

Methods inherited from class ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught

Modifier and Type	Method	Description
void	channelActive(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelActive() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	channelRegistered(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelRegistered() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	channelUnregistered(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelUnregistered() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	channelWritabilityChanged(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelWritabilityChanged() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	exceptionCaught(ChannelHandlerContext ctx, Throwable cause)	Calls ChannelHandlerContext.fireExceptionCaught(Throwable) to forward to the next ChannelHandler in the ChannelPipeline.

Methods inherited from class ChannelHandlerAdapter

ensureNotSharable, handlerAdded, isSharable

Modifier and Type	Method	Description
protected void	ensureNotSharable()	Throws IllegalStateException if ChannelHandlerAdapter.isSharable() returns true
void	handlerAdded(ChannelHandlerContext ctx)	Do nothing by default, sub-classes may override this method.
boolean	isSharable()	Return true if the implementation is ChannelHandler.Sharable and so can be added to different ChannelPipelines.

Methods inherited from class Object

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

Constructor Details

JsonObjectDecoder

public JsonObjectDecoder()

JsonObjectDecoder

public JsonObjectDecoder(int maxObjectLength)

JsonObjectDecoder

public JsonObjectDecoder(boolean streamArrayElements)

JsonObjectDecoder

public JsonObjectDecoder(int maxObjectLength,
 boolean streamArrayElements)

Parameters:

maxObjectLength - maximum number of bytes a JSON object/array may use (including braces and all). Objects exceeding this length are dropped and an TooLongFrameException is thrown.

streamArrayElements - if set to true and the "top level" JSON object is an array, each of its entries is passed through the pipeline individually and immediately after it was fully received, allowing for arrays with "infinitely" many elements.

Method Details

decode

protected void decode(ChannelHandlerContext ctx,
 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

extractObject

protected ByteBuf extractObject(ChannelHandlerContext ctx,
 ByteBuf buffer,
 int index,
 int length)

Override this method if you want to filter the json objects/arrays that get passed through the pipeline.