NETTY+WEBSOCKET在握手成功后进行验证

具体需求:
在建立websocket连接后,对用户传过来的url中的token参数进行验证,再从缓存中获取该用户信息

方法步骤:
1.继承netty包里的WebSocketServerProtocolHandler,重写里面的handlerAdded方法,用自己handshakehandler来替换它

    @Override
    public void handlerAdded(ChannelHandlerContext ctx) {
        ChannelPipeline cp = ctx.pipeline();
        if (cp.get(ZZKWebSocketServerProtocolHandshakeHandler.class) == null) {
            // Add the WebSocketHandshakeHandler before this one.

**********在这里写入自己的HandshakeHandler*********
            ctx.pipeline().addBefore(ctx.name(), ZZKWebSocketServerProtocolHandshakeHandler.class.getName(),
                    new ZZKWebSocketServerProtocolHandshakeHandler(websocketPath, subprotocols,
                            allowExtensions, maxFramePayloadSize, allowMaskMismatch, checkStartsWith));
        }
****************************************************

        if (cp.get(Utf8FrameValidator.class) == null) {
            // Add the UFT8 checking before this one.
            ctx.pipeline().addBefore(ctx.name(), Utf8FrameValidator.class.getName(),
                    new Utf8FrameValidator());
        }
    }

2.复制WebSocketServerProtocolHandshakeHandler这个类,重新命名,在里面的channelRead方法里写入自己的业务逻辑,具体位置在添加channelfuture的闭包里,if(future.isSuccess())..............

    @Override
    public void channelRead(final ChannelHandlerContext ctx, Object msg) throws Exception {
        final FullHttpRequest req = (FullHttpRequest) msg;
        if (isNotWebSocketPath(req)) {
            ctx.fireChannelRead(msg);
            return;
        }

        try {
            if (req.method() != GET) {
                sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN));
                return;
            }

            final WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(
                    getWebSocketLocation(ctx.pipeline(), req, websocketPath), subprotocols,
                    allowExtensions, maxFramePayloadSize, allowMaskMismatch);
            final WebSocketServerHandshaker handshaker = wsFactory.newHandshaker(req);
            if (handshaker == null) {
                WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel());
            } else {
                final ChannelFuture handshakeFuture = handshaker.handshake(ctx.channel(), req);
                handshakeFuture.addListener(new ChannelFutureListener() {
                    @Override
                    public void operationComplete(ChannelFuture future) throws Exception {
                        if (!future.isSuccess()) {
                            ctx.fireExceptionCaught(future.cause());
                        } else {
                            // Kept for compatibility
                            ctx.fireUserEventTriggered(
                                    WebSocketServerProtocolHandler.ServerHandshakeStateEvent.HANDSHAKE_COMPLETE);
                            ctx.fireUserEventTriggered(
                                    new ZZKWebSocketServerProtocolHandler.HandshakeComplete(
                                            req.uri(), req.headers(), handshaker.selectedSubprotocol()));
                            //这里写业务逻辑处理
                            BeanHolder.get(MessageHelperService.class).validate(ctx, req);

                        }
                    }
                });
                ZZKWebSocketServerProtocolHandshakeHandler.setHandshaker(ctx.channel(), handshaker);
                ctx.pipeline().replace(this, "WS403Responder",
                        ZZKWebSocketServerProtocolHandler.forbiddenHttpRequestResponder());
            }
        } finally {
            req.release();
        }
    }

最后在netty的handler链中加入该handler

        ChannelPipeline pipeline = channel.pipeline();

        ....
        pipeline.addLast(new ZZKHttpRequestHandler());//区分http请求,读取html页面并写回客户端浏览器
        pipeline.addLast(new ZZKWebSocketServerProtocolHandler());//会拦截该地址的请求,会区分访问是控制针访问还是数据帧访问,数据帧访问会交给自己的控制器处理
        pipeline.addLast(new ZZKChatServerHandler());//向客户端发送数据