添加gateway依赖

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-gateway</artifactId>
</dependency>

创建一个LogTimeGateWayFilterFactory类，可以不是这个名字但是后面必须是xxxGateWayFilterFactory
然后继承AbstractNameValueGatewayFilterFactory

@Component
@Slf4j
public class LogTimeGatewayFilterFactory extends AbstractNameValueGatewayFilterFactory {
    @Override
    public GatewayFilter apply(NameValueConfig config) {
        return new GatewayFilter() {
            @Override
            public Mono<Void> filter(ServerWebExchange exchange,GatewayFilterChain chain) {
                //获取配置的超时时间
                String value = ServerWebExchangeUtils.expand(exchange, config.getValue());
                Integer timespan = Integer.valueOf(value);
                //获取开始时间
                long start = System.currentTimeMillis();
                // 往下执行完并返回后   操作.then对执行结果操作完之后在返回
                return chain.filter(exchange).then(Mono.fromRunnable(()->{
                    //获取结束时间
                    long end = System.currentTimeMillis();
                    //获取请求耗时
                    long time = end - start;
                    //判断是否超时
                    if(time > timespan*1000){
                        log.debug("请求耗时:{}ms",time);
                    }
                }));
            }

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

配置文件里配置，LogTime就是类名，但是不能带着GateWayFilterFactory