SpringCloud Gateway中GatewayFilterChain执行流程详解

return new DefaultGatewayFilterChain(combined).filter(exchange);

		@Override
		public Mono<Void> filter(ServerWebExchange exchange) {
			return Mono.defer(() -> {
				if (this.index < filters.size()) {
                      //filters就是上面传入的所有过滤器，index就是当前的索引
					GatewayFilter filter = filters.get(this.index);
                      //index+1，获取下一个过滤器
					DefaultGatewayFilterChain chain = new DefaultGatewayFilterChain(this, this.index + 1);
                      //分别执行每个过滤器的filter方法
					return filter.filter(exchange, chain);
				}
				else {
					return Mono.empty(); // complete
				}
			});
		}
	}

		Flux<HttpClientResponse> responseFlux = getHttpClient(route, exchange).headers(headers -> {
			headers.add(httpHeaders);
			// Will either be set below, or later by Netty
			headers.remove(HttpHeaders.HOST);
			if (preserveHost) {
				String host = request.getHeaders().getFirst(HttpHeaders.HOST);
				headers.add(HttpHeaders.HOST, host);
			}
		}).request(method).uri(url).send((req, nettyOutbound) -> {
			if (log.isTraceEnabled()) {
				nettyOutbound.withConnection(connection -> log.trace("outbound route: "
						+ connection.channel().id().asshortText() + ", inbound: " + exchange.getLogPrefix()));
			}
             //具体调用发送request的位置
			return nettyOutbound.send(request.getBody().map(this::getByteBuf));