MessageToMessageCodec Class — netty Architecture

Source Code

codec-base/src/main/java/io/netty/handler/codec/MessageToMessageCodec.java lines 55–162

public abstract class MessageToMessageCodec<INBOUND_IN, OUTBOUND_IN> extends ChannelDuplexHandler {

    private final MessageToMessageDecoder<Object> decoder = new MessageToMessageDecoder<Object>(Object.class) {

        @Override
        public boolean acceptInboundMessage(Object msg) throws Exception {
            return MessageToMessageCodec.this.acceptInboundMessage(msg);
        }

        @Override
        @SuppressWarnings("unchecked")
        protected void decode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
            MessageToMessageCodec.this.decode(ctx, (INBOUND_IN) msg, out);
        }

        @Override
        public boolean isSharable() {
            return MessageToMessageCodec.this.isSharable();
        }
    };
    private final MessageToMessageEncoder<Object> encoder = new MessageToMessageEncoder<Object>(Object.class) {

        @Override
        public boolean acceptOutboundMessage(Object msg) throws Exception {
            return MessageToMessageCodec.this.acceptOutboundMessage(msg);
        }

        @Override
        @SuppressWarnings("unchecked")
        protected void encode(ChannelHandlerContext ctx, Object msg, List<Object> out) throws Exception {
            MessageToMessageCodec.this.encode(ctx, (OUTBOUND_IN) msg, out);
        }

        @Override
        public boolean isSharable() {
            return MessageToMessageCodec.this.isSharable();
        }
    };

    private final TypeParameterMatcher inboundMsgMatcher;
    private final TypeParameterMatcher outboundMsgMatcher;

    /**
     * Create a new instance which will try to detect the types to decode and encode out of the type parameter
     * of the class.
     */
    protected MessageToMessageCodec() {
        inboundMsgMatcher = TypeParameterMatcher.find(this, MessageToMessageCodec.class, "INBOUND_IN");
        outboundMsgMatcher = TypeParameterMatcher.find(this, MessageToMessageCodec.class, "OUTBOUND_IN");
    }

    /**
     * Create a new instance.
     *
     * @param inboundMessageType    The type of messages to decode
     * @param outboundMessageType   The type of messages to encode
     */
    protected MessageToMessageCodec(
            Class<? extends INBOUND_IN> inboundMessageType, Class<? extends OUTBOUND_IN> outboundMessageType) {
        inboundMsgMatcher = TypeParameterMatcher.get(inboundMessageType);
        outboundMsgMatcher = TypeParameterMatcher.get(outboundMessageType);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        decoder.channelRead(ctx, msg);
    }

    @Override
    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
        decoder.channelReadComplete(ctx);
    }

    @Override
    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
        encoder.write(ctx, msg, promise);
    }

    /**
     * Returns {@code true} if and only if the specified message can be decoded by this codec.
     *