netty怎么判断客户端是纯socket还是websocket ：报错

从channel是判断不出来的, websocket协议在channel中没有体现. 

如果用netty, 绑定一个端口来接收socket, websocket的连接, 可以尝试如下:

1. 将它们的inbound,outbound处理类, 都在初始化时加进去, websocket的放在前面.

2. websocket在请求连接后, 会有一个http握手请求, 普通socket连接也可以在websocket 自定义inbound处理类中处理

3. 判断是否为 websocket请求, 是(pipeline中移除socket的处理类), 否(pipeline中移除websocket的处理类), 以后再来的消息, 就只会到各自的处理类中了.

不同端口监听

public class WSProtobufServerInitialzer extends ChannelInitializer<SocketChannel> {

    @Override
    protected void initChannel(SocketChannel ch) throws Exception {
        ChannelPipeline pipeline = ch.pipeline();

        pipeline.addLast(new ReadTimeoutHandler(60)); // 长时间不写会断


        // ====================== 增加心跳支持 start    ======================
        // 针对客户端，如果在1分钟时没有向服务端发送读写心跳(ALL)，则主动断开
        // 如果是读空闲或者写空闲，不处理
        pipeline.addLast(new IdleStateHandler(0, 0, 15));
        // 自定义的空闲状态检测

        //判断是websocket 还是普通socket
        //如果是websocket 则添加HttpServerCodec()等   否则添加new ProtobufDecoder（）等
        pipeline.addLast(new SocketChooseHandle());

    }

}

在SocketChooseHandle()中通过
private String getBufStart(ByteBuf in) {
    int length = in.readableBytes();
    if (length > MAX_LENGTH) {
        length = MAX_LENGTH;
    }

    // 标记读位置
    in.markReaderIndex();
    byte[] content = new byte[length];
    in.readBytes(content);
    return new String(content);
}获取握手的协议前缀

/**
 * 协议初始化
 * <p>
 * 用来判定实际使用什么协议.</b>
 */
public class SocketChooseHandle extends ByteToMessageDecoder {
    /**
     * 默认暗号长度为23
     */
    private static final int MAX_LENGTH = 23;
    /**
     * WebSocket握手的协议前缀
     */
    private static final String WEBSOCKET_PREFIX = "GET /";


    @Override
    protected void decode(ChannelHandlerContext ch, ByteBuf in, List<Object> out) throws Exception {
        String protocol = getBufStart(in);

        ChannelPipeline pipeline = ch.pipeline();
        if (protocol.startsWith(WEBSOCKET_PREFIX)) {
            //websocket 基于http协议，所以要有http  //如果不是websocket 则删除
            pipeline.addLast(new HttpServerCodec());
            // 对写大数据流的支持
            pipeline.addLast(new ChunkedWriteHandler());
            // 对httpMessage进行聚合，聚合成FullHttpRequest或FullHttpResponse
            // 几乎在netty中的编程，都会使用到此hanler
            pipeline.addLast(new HttpObjectAggregator(1024 * 64));

            pipeline.addLast(new WebSocketServerProtocolHandler("/web"));


            // 协议包解码
            pipeline.addLast(new MessageToMessageDecoder<WebSocketFrame>() {
                @Override
                protected void decode(ChannelHandlerContext ctx, WebSocketFrame frame, List<Object> objs) throws Exception {
                    ByteBuf buf = frame.content();
                    objs.add(buf);
                    buf.retain();
                }
            });

            // 协议包解码时指定Protobuf字节数实例化为CommonProtocol类型
            pipeline.addLast(new ProtobufDecoder(MyProbuf.DataContent.getDefaultInstance()));


            pipeline.addLast(new ProtobufVarint32LengthFieldPrepender());

            // 协议包编码
            pipeline.addLast(new MessageToMessageEncoder<MessageLiteOrBuilder>() {
                @Override
                protected void encode(ChannelHandlerContext ctx, MessageLiteOrBuilder msg, List<Object> out) throws Exception {
                    ByteBuf result = null;
                    if (msg instanceof MessageLite) {
                        result = Unpooled.wrappedBuffer(((MessageLite) msg).toByteArray());
                    }
                    if (msg instanceof MessageLite.Builder) {
                        result = Unpooled.wrappedBuffer(((MessageLite.Builder) msg).build().toByteArray());
                    }

                    // ==== 上面代码片段是拷贝自TCP ProtobufEncoder 源码 ====
                    // 然后下面再转成websocket二进制流，因为客户端不能直接解析protobuf编码生成的

                    WebSocketFrame frame = new BinaryWebSocketFrame(result);
                    out.add(frame);
                }
            });

        } else {
            // 解码和编码，应和客户端一致
            //传输的协议 Protobuf
            pipeline.addLast(new ProtobufVarint32FrameDecoder());
            pipeline.addLast(new ProtobufDecoder(MyProbuf.DataContent.getDefaultInstance()));
            pipeline.addLast(new ProtobufVarint32LengthFieldPrepender());
            pipeline.addLast(new ProtobufEncoder());
        }

        //添加自定义处理器
        pipeline.addLast(new ProtobufHandler());

        in.resetReaderIndex();
        pipeline.remove(this.getClass());

    }


    private String getBufStart(ByteBuf in) {
        int length = in.readableBytes();
        if (length > MAX_LENGTH) {
            length = MAX_LENGTH;
        }

        // 标记读位置
        in.markReaderIndex();
        byte[] content = new byte[length];
        in.readBytes(content);
        return new String(content);
    }
}