io.netty.handler.codec

Class MessageToMessageDecoder<I>

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.handler.codec.MessageToMessageDecoder<I>

All Implemented Interfaces:

io.netty.channel.ChannelHandler, io.netty.channel.ChannelInboundHandler

Direct Known Subclasses:

Base64Decoder, ByteArrayDecoder, ProtobufDecoder, StringDecoder

public abstract class MessageToMessageDecoder<I>
extends io.netty.channel.ChannelInboundHandlerAdapter

ChannelInboundHandlerAdapter which decodes from one message to an other message. For example here is an implementation which decodes a String to an Integer which represent the length of the String.

     public class StringToIntegerDecoder extends
             MessageToMessageDecoder<String> {

         @Override
         public void decode(ChannelHandlerContext ctx, String message,
                 MessageList out) throws Exception {
             out.add(message.length());
         }
     }
 

Be aware that you need to call ReferenceCounted.retain() on messages that are just passed through if they are of type ReferenceCounted. This is needed as the MessageToMessageDecoder will call ReferenceCounted.release() on decoded messages.

Nested Class Summary

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

io.netty.channel.ChannelHandler.Sharable

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	MessageToMessageDecoder()
protected	MessageToMessageDecoder(Class<? extends I> inboundMessageType)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	acceptInboundMessage(Object msg)
protected abstract void	decode(io.netty.channel.ChannelHandlerContext ctx, I msg, io.netty.channel.MessageList<Object> out) Decode from one message to an other.
void	messageReceived(io.netty.channel.ChannelHandlerContext ctx, io.netty.channel.MessageList<Object> msgs)

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelInactive, channelReadSuspended, channelRegistered, channelUnregistered, channelWritabilityChanged, 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.ChannelHandler

exceptionCaught, handlerAdded, handlerRemoved

Constructor Detail

MessageToMessageDecoder

protected MessageToMessageDecoder()

MessageToMessageDecoder

protected MessageToMessageDecoder(Class<? extends I> inboundMessageType)

Method Detail

acceptInboundMessage

public boolean acceptInboundMessage(Object msg)
                             throws Exception

Throws:

Exception

messageReceived

public void messageReceived(io.netty.channel.ChannelHandlerContext ctx,
                   io.netty.channel.MessageList<Object> msgs)
                     throws Exception

Specified by:

messageReceived in interface io.netty.channel.ChannelInboundHandler

Overrides:

messageReceived in class io.netty.channel.ChannelInboundHandlerAdapter

Throws:

Exception

decode

protected abstract void decode(io.netty.channel.ChannelHandlerContext ctx,
          I msg,
          io.netty.channel.MessageList<Object> out)
                        throws Exception

Decode from one message to an other. This method will be called till either the MessageList has nothing left or till this method returns null.

Parameters:

ctx - the ChannelHandlerContext which this MessageToMessageDecoder belongs to

msg - the message to decode to an other one

out - the MessageList to which decoded messages should be added

Throws:

Exception - is thrown if an error accour