io.netty.handler.codec

Class ByteToMessageDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelStateHandlerAdapter

io.netty.channel.ChannelInboundByteHandlerAdapter

io.netty.handler.codec.ByteToMessageDecoder

All Implemented Interfaces:

ChannelHandler, ChannelInboundByteHandler, ChannelStateHandler

Direct Known Subclasses:

DelimiterBasedFrameDecoder, FixedLengthFrameDecoder, LengthFieldBasedFrameDecoder, LineBasedFrameDecoder, ProtobufVarint32FrameDecoder, ReplayingDecoder, SpdyFrameDecoder

public abstract class ByteToMessageDecoder
extends ChannelInboundByteHandlerAdapter

ChannelInboundByteHandler which decodes bytes in a stream-like fashion from one ByteBuf to an other Message type. For example here is an implementation which reads all readable bytes from the input ByteBuf and create a new ByteBuf.

     public class SquareDecoder extends ByteToMessageDecoder {
         @Override
         public Object decode(ChannelHandlerContext ctx, ByteBuf in)
                 throws Exception {
             return in.readBytes(in.readableBytes());
         }
     }
 

Nested Class Summary

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

ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor and Description
ByteToMessageDecoder()

Method Summary

Methods

Modifier and Type	Method and Description
protected void	callDecode(ChannelHandlerContext ctx, ByteBuf in)
void	channelInactive(ChannelHandlerContext ctx) Calls ChannelHandlerContext.fireChannelInactive() to forward to the next ChannelStateHandler in the ChannelPipeline.
void	channelReadSuspended(ChannelHandlerContext ctx) Calls ChannelHandlerContext.fireChannelReadSuspended() to forward to the next ChannelHandler in the ChannelPipeline.
protected abstract Object	decode(ChannelHandlerContext ctx, ByteBuf in) Decode the from one ByteBuf to an other.
protected Object	decodeLast(ChannelHandlerContext ctx, ByteBuf in) Is called one last time when the ChannelHandlerContext goes in-active.
void	inboundBufferUpdated(ChannelHandlerContext ctx, ByteBuf in) Callback which will get notifed once the given ByteBuf received more data to read.
boolean	isSingleDecode() If true then only one message is decoded on each ChannelInboundByteHandlerAdapter.inboundBufferUpdated(ChannelHandlerContext) call.
void	setSingleDecode(boolean singleDecode) If set then only one message is decoded on each ChannelInboundByteHandlerAdapter.inboundBufferUpdated(ChannelHandlerContext) call.

Methods inherited from class io.netty.channel.ChannelInboundByteHandlerAdapter

discardInboundReadBytes, freeInboundBuffer, inboundBufferUpdated, newInboundBuffer

Methods inherited from class io.netty.channel.ChannelStateHandlerAdapter

channelActive, channelRegistered, channelUnregistered, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

afterAdd, afterRemove, beforeAdd, beforeRemove, exceptionCaught

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, userEventTriggered

Methods inherited from interface io.netty.channel.ChannelHandler

afterAdd, afterRemove, beforeAdd, beforeRemove, exceptionCaught

Constructor Detail

ByteToMessageDecoder

public ByteToMessageDecoder()

Method Detail

setSingleDecode

public void setSingleDecode(boolean singleDecode)

If set then only one message is decoded on each ChannelInboundByteHandlerAdapter.inboundBufferUpdated(ChannelHandlerContext) call. This may be useful if you need to do some protocol upgrade and want to make sure nothing is mixed up. Default is false as this has performance impacts.

isSingleDecode

public boolean isSingleDecode()

If true then only one message is decoded on each ChannelInboundByteHandlerAdapter.inboundBufferUpdated(ChannelHandlerContext) call. Default is false as this has performance impacts.

inboundBufferUpdated

public void inboundBufferUpdated(ChannelHandlerContext ctx,
                        ByteBuf in)
                          throws Exception

Description copied from class: ChannelInboundByteHandlerAdapter

Callback which will get notifed once the given ByteBuf received more data to read. What will be done with the data at this point is up to the implementation. Implementations may choose to read it or just let it in the buffer to read it later.

Specified by:

inboundBufferUpdated in class ChannelInboundByteHandlerAdapter

Throws:

Exception

channelReadSuspended

public void channelReadSuspended(ChannelHandlerContext ctx)
                          throws Exception

Description copied from class: ChannelStateHandlerAdapter

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

Specified by:

channelReadSuspended in interface ChannelStateHandler

Overrides:

channelReadSuspended in class ChannelStateHandlerAdapter

Throws:

Exception

channelInactive

public void channelInactive(ChannelHandlerContext ctx)
                     throws Exception

Description copied from class: ChannelStateHandlerAdapter

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

Specified by:

channelInactive in interface ChannelStateHandler

Overrides:

channelInactive in class ChannelStateHandlerAdapter

Throws:

Exception

callDecode

protected void callDecode(ChannelHandlerContext ctx,
              ByteBuf in)

decode

protected abstract Object decode(ChannelHandlerContext ctx,
            ByteBuf in)
                          throws Exception

Decode the from one ByteBuf to an other. This method will be called till either the input ByteBuf has nothing to read anymore, till nothing was read from the input ByteBuf or till this method returns null.

Parameters:

ctx - the ChannelHandlerContext which this ByteToByteDecoder belongs to

in - the ByteBuf from which to read data

Returns:

message the message to which the content of the ByteBuf was decoded, or null if there was not enough data left in the ByteBuf to decode.

Throws:

Exception - is thrown if an error accour

decodeLast

protected Object decodeLast(ChannelHandlerContext ctx,
                ByteBuf in)
                     throws Exception

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

Throws:

Exception