io.netty.handler.codec

Class MessageToMessageEncoder<I>

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelOutboundHandlerAdapter

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

All Implemented Interfaces:

io.netty.channel.ChannelHandler, io.netty.channel.ChannelOutboundHandler

Direct Known Subclasses:

Base64Encoder, ByteArrayEncoder, ProtobufEncoder

public abstract class MessageToMessageEncoder<I>
extends io.netty.channel.ChannelOutboundHandlerAdapter

ChannelOutboundHandlerAdapter which encodes from one message to an other message For example here is an implementation which decodes an Integer to an String.

     public class IntegerToStringEncoder extends
             MessageToMessageEncoder<Integer> {

         @Override
         public void encode(ChannelHandlerContext ctx, Integer message, MessageList out)
                 throws Exception {
             out.add(message.toString());
         }
     }
 

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 MessageToMessageEncoder will call ReferenceCounted.release() on encoded 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	MessageToMessageEncoder()
protected	MessageToMessageEncoder(Class<? extends I> outboundMessageType)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	acceptOutboundMessage(Object msg)
protected abstract void	encode(io.netty.channel.ChannelHandlerContext ctx, I msg, io.netty.channel.MessageList<Object> out) Encode from one message to an other.
void	write(io.netty.channel.ChannelHandlerContext ctx, io.netty.channel.MessageList<Object> msgs, io.netty.channel.ChannelPromise promise)

Methods inherited from class io.netty.channel.ChannelOutboundHandlerAdapter

bind, close, connect, deregister, disconnect, read

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

MessageToMessageEncoder

protected MessageToMessageEncoder()

MessageToMessageEncoder

protected MessageToMessageEncoder(Class<? extends I> outboundMessageType)

Method Detail

acceptOutboundMessage

public boolean acceptOutboundMessage(Object msg)
                              throws Exception

Throws:

Exception

write

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

Specified by:

write in interface io.netty.channel.ChannelOutboundHandler

Overrides:

write in class io.netty.channel.ChannelOutboundHandlerAdapter

Throws:

Exception

encode

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

Encode 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 MessageToMessageEncoder belongs to

msg - the message to encode to an other one

out - the MessageList into which the encoded msg should be added needs to do some kind of aggragation

Throws:

Exception - is thrown if an error accour