spring cloud gateway 全局过滤器的实现

public interface GlobalFilter {
  Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain);
}

@Configuration
public class ExampleConfiguration {
  private Logger log = LoggerFactory.getLogger(ExampleConfiguration.class);

  @Bean
  @Order(-1)
  public GlobalFilter a() {
    return (exchange, chain) -> {
      log.info("first pre filter");
      return chain.filter(exchange).then(Mono.fromRunnable(() -> {
        log.info("third post filter");
      }));
    };
  }

  @Bean
  @Order(0)
  public GlobalFilter b() {
    return (exchange, chain) -> {
      log.info("second pre filter");
      return chain.filter(exchange).then(Mono.fromRunnable(() -> {
        log.info("second post filter");
      }));
    };
  }

  @Bean
  @Order(1)
  public GlobalFilter c() {
    return (exchange, chain) -> {
      log.info("third pre filter");
      return chain.filter(exchange).then(Mono.fromRunnable(() -> {
        log.info("first post filter");
      }));
    };
  }
}

@Component
public class IPCheckFilter implements GlobalFilter, Ordered {

  @Override
  public int getOrder() {
    return 0;
  }

  @Override
  public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    HttpHeaders headers = exchange.getRequest().getHeaders();
    // 此处写死了，演示用，实际中需要采取配置的方式
    if (getIp(headers).equals("127.0.0.1")) {
      ServerHttpResponse response = exchange.getResponse();
      ResponseData data = new ResponseData();
      data.setCode(401);
      data.setMessage("非法请求");
      byte[] datas = JsonUtils.toJson(data).getBytes(StandardCharsets.UTF_8);
      DataBuffer buffer = response.bufferFactory().wrap(datas);
      response.setStatusCode(HttpStatus.UNAUTHORIZED);
      response.getHeaders().add("Content-Type", "application/json;charset=UTF-8");
      return response.writeWith(Mono.just(buffer));
    }
    return chain.filter(exchange);
  }

  // 这边从请求头中获取用户的实际IP,根据Nginx转发的请求头获取
  private String getIp(HttpHeaders headers) {
    return "127.0.0.1";
  }

}

exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, requestUrl);

URI requestUrl = exchange.getRequiredAttribute(GATEWAY_REQUEST_URL_ATTR);

@Component
public class DebugFilter implements GlobalFilter, Ordered {

  @Override
  public int getOrder() {
    return 10101;
  }

  @Override
  public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
    try {
      exchange.getAttributes().put(GATEWAY_REQUEST_URL_ATTR, new URI("http://192.168.31.245:8081/house/hello2"));
    } catch (URISyntaxException e) {
      e.printStackTrace();
    }
    return chain.filter(exchange);
  }

}