1.找规律

局部过滤器命名规则 XXXGatewayFilterFactory， 必须以GatewayFilterFactory结尾。

/*  注意名称约定
*   AddRequestHeaderGatewayFilterFactory    配置的时候写的是 AddRequestHeader
*   AddRequestParameterGatewayFilterFactory 配置的时候写的是 AddRequestParameter
*   LogTimeGatewayFilterFactory   配置的时候写什么？ 
* */

2.接口耗时过滤器

package com.by.filter;

import lombok.extern.slf4j.Slf4j;
import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.factory.AbstractNameValueGatewayFilterFactory;
import org.springframework.cloud.gateway.filter.factory.AddRequestHeaderGatewayFilterFactory;
import org.springframework.cloud.gateway.support.GatewayToStringStyler;
import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

@Component
@Slf4j
public class LogTimeGatewayFilterFactory extends AbstractNameValueGatewayFilterFactory {


    public GatewayFilter apply(final AbstractNameValueGatewayFilterFactory.NameValueConfig config) {
        return new GatewayFilter() {
            public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
                String value = ServerWebExchangeUtils.expand(exchange, config.getValue());
                int times = Integer.parseInt(value);
                long start = System.currentTimeMillis();
                return chain.filter(exchange).then(Mono.fromRunnable(() -> {
                    long end = System.currentTimeMillis();
                    long time = end - start;
                    if(time>times*1000){
                        log.info("请求耗时过长，耗时：{}",time);
                    }
                }));
            }

            public String toString() {
                return GatewayToStringStyler.filterToStringCreator(LogTimeGatewayFilterFactory.this).append(config.getName(), config.getValue()).toString();
            }
        };
    }
}

3.如何使用