概述

全局过滤器作用于所有的路由，不需要单独配置，我们可以用它来实现很多统一化处理的业务需求，比如权限认证，IP 访问限制等等。

The GlobalFilter interface has the same signature as GatewayFilter. These are special filters that are conditionally applied to all routes. (This interface and usage are subject to change in future milestones).

声明周期

Spring Cloud Gateway 基于 Project Reactor 和 WebFlux，采用响应式编程风格，打开它的 Filter 的接口 GlobalFilter 你会发现它只有一个方法 filter。

创建全局过滤器

实现 GlobalFilter, Ordered 接口并在类上增加 @Component 注解就可以使用过滤功能了，非常简单方便

AuthFilter

package com.wj.hello.spring.cloud.gateway.filters;

import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.collect.Maps;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.GlobalFilter;
import org.springframework.core.Ordered;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.http.HttpStatus;
import org.springframework.http.server.reactive.ServerHttpResponse;
import org.springframework.stereotype.Component;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import java.util.Map;

/**
 * 鉴权过滤器(全局过滤器)
 */
@Component // 向Spring声明
public class AuthFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        String token = exchange.getRequest().getQueryParams().getFirst("token");

        if (token == null || token.isEmpty()) {
            ServerHttpResponse response = exchange.getResponse();

            // 封装错误信息
            Map<String, Object> responseData = Maps.newHashMap();
            responseData.put("code", 401);
            responseData.put("message", "非法请求");
            responseData.put("cause", "Token is empty");

            try {
                // 将信息转换为 JSON
                ObjectMapper objectMapper = new ObjectMapper();
                byte[] data = objectMapper.writeValueAsBytes(responseData);

                // 输出错误信息到页面
                DataBuffer buffer = response.bufferFactory().wrap(data);
                response.setStatusCode(HttpStatus.UNAUTHORIZED);
                response.getHeaders().add("Content-Type", "application/json;charset=UTF-8");
                return response.writeWith(Mono.just(buffer));
            } catch (JsonProcessingException e) {
                e.printStackTrace();
            }
        }

        return chain.filter(exchange);
    }

    /**
     * 设置过滤器的执行顺序，数字越小，级别越高
     * @return
     */
    @Override
    public int getOrder() {
        return Ordered.LOWEST_PRECEDENCE;
    }
}

测试过滤器

浏览器访问：http://localhost:9000/nacos-consumer/echo/app/name 网页显示

浏览器访问：http://localhost:9000/nacos-consumer/echo/app/name?token=123456 网页显示

Hello Nacos Discovery nacos-consumer i am from port 8081

更多的路由规则可查看官网

Global Filters：全局过滤
GatewayFilter：局部过滤