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

Nested classes/interfaces inherited from interface ChannelHandler

ChannelHandler.Sharable

Field Summary

Fields

Modifier and Type	Field	Description
private int	idx
private boolean	insideString
private int	lastReaderIndex
private final int	maxObjectLength
private int	openBraces
private static final int	ST_CORRUPTED
private static final int	ST_DECODING_ARRAY_STREAM
private static final int	ST_DECODING_NORMAL
private static final int	ST_INIT
private int	state
private final boolean	streamArrayElements

Fields inherited from class ByteToMessageDecoder

COMPOSITE_CUMULATOR, MERGE_CUMULATOR

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, java.util.List<java.lang.Object> out)	Decode the from one ByteBuf to an other.
private void	decodeByte(byte c, ByteBuf in, int idx)
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.
private void	initDecoding(byte openingBrace)
private void	reset()

Methods inherited from class ByteToMessageDecoder

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

Methods inherited from class ChannelInboundHandlerAdapter

channelActive, channelRegistered, channelUnregistered, channelWritabilityChanged, exceptionCaught

Methods inherited from class 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 ChannelHandler

handlerAdded

Field Details

ST_CORRUPTED

private static final int ST_CORRUPTED

See Also:

• Constant Field Values

ST_INIT

private static final int ST_INIT

See Also:

• Constant Field Values

ST_DECODING_NORMAL

private static final int ST_DECODING_NORMAL

See Also:

• Constant Field Values

ST_DECODING_ARRAY_STREAM

private static final int ST_DECODING_ARRAY_STREAM

See Also:

• Constant Field Values

openBraces

private int openBraces

idx

private int idx

lastReaderIndex

private int lastReaderIndex

state

private int state

insideString

private boolean insideString

maxObjectLength

private final int maxObjectLength

streamArrayElements

private final boolean streamArrayElements

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,
 java.util.List<java.lang.Object> out)
               throws java.lang.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:

java.lang.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.

decodeByte

private void decodeByte(byte c,
 ByteBuf in,
 int idx)

initDecoding

private void initDecoding(byte openingBrace)

reset

private void reset()