support @Order (#2805)

Co-authored-by: xjs1919 <xjs@163.com>

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/handler/FilteringWebHandler.java

@@ -33,6 +33,8 @@ import org.springframework.cloud.gateway.route.Route;
 import org.springframework.core.DecoratingProxy;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.annotation.Order;
 import org.springframework.web.server.ServerWebExchange;
 import org.springframework.web.server.WebHandler;
 
@@ -64,6 +66,12 @@ public class FilteringWebHandler implements WebHandler {
 				int order = ((Ordered) filter).getOrder();
 				return new OrderedGatewayFilter(gatewayFilter, order);
 			}
+			else {
+				Order order = AnnotationUtils.findAnnotation(filter.getClass(), Order.class);
+				if (order != null) {
+					return new OrderedGatewayFilter(gatewayFilter, order.value());
+				}
+			}
 			return gatewayFilter;
 		}).collect(Collectors.toList());
 	}