io.netty.handler.codec

Class ByteToByteDecoder

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelStateHandlerAdapter

io.netty.channel.ChannelInboundByteHandlerAdapter

io.netty.handler.codec.ByteToByteDecoder

All Implemented Interfaces:

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

Direct Known Subclasses:

SnappyFramedDecoder, ZlibDecoder

public abstract class ByteToByteDecoder
extends io.netty.channel.ChannelInboundByteHandlerAdapter

ChannelInboundByteHandlerAdapter which decodes bytes in a stream-like fashion from one ByteBuf to an other. This kind of decoder is often useful for doing on-the-fly processiing like i.e. compression. But you can also do other things with it. For example here is an implementation which reads Integers from the input ByteBuf and square them before write them to the output ByteBuf.

     public class SquareDecoder extends ByteToByteDecoder {
         @Override
         public void decode(ChannelHandlerContext ctx, ByteBuf in, ByteBuf out)
                 throws Exception {
             if (in.readableBytes() < 4) {
                 return;
             }
             int value = in.readInt();
             out.writeInt(value * value);
         }
     }
 

Nested Class Summary

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

io.netty.channel.ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor and Description
ByteToByteDecoder()

Method Summary

Methods

Modifier and Type	Method and Description
void	channelInactive(io.netty.channel.ChannelHandlerContext ctx)
protected abstract void	decode(io.netty.channel.ChannelHandlerContext ctx, io.netty.buffer.ByteBuf in, io.netty.buffer.ByteBuf out) Decode the from one ByteBuf to an other.
protected void	decodeLast(io.netty.channel.ChannelHandlerContext ctx, io.netty.buffer.ByteBuf in, io.netty.buffer.ByteBuf out) Is called one last time when the ChannelHandlerContext goes in-active.
void	inboundBufferUpdated(io.netty.channel.ChannelHandlerContext ctx, io.netty.buffer.ByteBuf in)
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, inboundBufferUpdated, newInboundBuffer

Methods inherited from class io.netty.channel.ChannelStateHandlerAdapter

channelActive, channelReadSuspended, channelRegistered, channelUnregistered, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

exceptionCaught, handlerAdded, handlerRemoved

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, channelReadSuspended, channelRegistered, channelUnregistered, userEventTriggered

Methods inherited from interface io.netty.channel.ChannelHandler

exceptionCaught, handlerAdded, handlerRemoved

Constructor Detail

ByteToByteDecoder

public ByteToByteDecoder()

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(io.netty.channel.ChannelHandlerContext ctx,
                        io.netty.buffer.ByteBuf in)
                          throws Exception

Specified by:

inboundBufferUpdated in class io.netty.channel.ChannelInboundByteHandlerAdapter

Throws:

Exception

channelInactive

public void channelInactive(io.netty.channel.ChannelHandlerContext ctx)
                     throws Exception

Specified by:

channelInactive in interface io.netty.channel.ChannelStateHandler

Overrides:

channelInactive in class io.netty.channel.ChannelStateHandlerAdapter

Throws:

Exception

decode

protected abstract void decode(io.netty.channel.ChannelHandlerContext ctx,
          io.netty.buffer.ByteBuf in,
          io.netty.buffer.ByteBuf out)
                        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 or till nothing was read from the input ByteBuf.

Parameters:

ctx - the ChannelHandlerContext which this ByteToByteDecoder belongs to

in - the ByteBuf from which to read data

out - the ByteBuf to which the decoded data will be written

Throws:

Exception - is thrown if an error accour

decodeLast

protected void decodeLast(io.netty.channel.ChannelHandlerContext ctx,
              io.netty.buffer.ByteBuf in,
              io.netty.buffer.ByteBuf out)
                   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, ByteBuf) but sub-classes may override this for some special cleanup operation.

Throws:

Exception