前言

Spring Cloud Gateway 是 Spring 官方推出的 API 网关，基于 WebFlux 实现，性能卓越。本文带你从零搭建一个生产级的微服务 API 网关。

一、核心概念

• Route（路由）：网关的基本构建块，包含 ID、目标 URI、Predicate、Filter
• Predicate（断言）：匹配请求条件（路径、Header、参数等）
• Filter（过滤器）：对请求进行前置/后置处理（鉴权、限流、日志等）

二、快速搭建

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

# application.yml
server:
  port: 8080

spring:
  application:
    name: api-gateway
  cloud:
    gateway:
      routes:
        - id: user-service
          uri: lb://user-service
          predicates:
            - Path=/api/users/**
          filters:
            - StripPrefix=1
        - id: order-service
          uri: lb://order-service
          predicates:
            - Path=/api/orders/**
          filters:
            - StripPrefix=1

      discovery:
        locator:
          enabled: true  # 自动发现服务

三、自定义全局过滤器（JWT 鉴权）

@Component
public class AuthGlobalFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange,
                              GatewayFilterChain chain) {
        String path = exchange.getRequest().getPath().value();
        // 白名单路径跳过鉴权
        if (path.startsWith("/api/auth/login") ||
            path.startsWith("/api/auth/register")) {
            return chain.filter(exchange);
        }
        String token = exchange.getRequest()
            .getHeaders().getFirst("Authorization");
        if (token == null || !token.startsWith("Bearer ")) {
            exchange.getResponse().setStatusCode(HttpStatus.UNAUTHORIZED);
            return exchange.getResponse().setComplete();
        }
        // 验证 JWT（简化示例）
        try {
            String jwt = token.substring(7);
            Claims claims = Jwts.parser()
                .setSigningKey("secret-key").parseClaimsJws(jwt).getBody();
            String userId = claims.getSubject();
            ServerHttpRequest request = exchange.getRequest()
                .mutate().header("X-User-Id", userId).build();
            return chain.filter(exchange.mutate().request(request).build());
        } catch (Exception e) {
            exchange.getResponse().setStatusCode(HttpStatus.UNAUTHORIZED);
            return exchange.getResponse().setComplete();
        }
    }

    @Override
    public int getOrder() { return -100; }
}

四、自定义 GatewayFilter（限流）

@Component
public class RateLimitFilter implements GatewayFilter, Ordered {

    private final RateLimiter rateLimiter = RateLimiter.create(100);

    @Override
    public Mono<Void> filter(ServerWebExchange exchange,
                              GatewayFilterChain chain) {
        if (!rateLimiter.tryAcquire()) {
            exchange.getResponse().setStatusCode(HttpStatus.TOO_MANY_REQUESTS);
            return exchange.getResponse().setComplete();
        }
        return chain.filter(exchange);
    }

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

# 在路由中使用自定义过滤器
spring.cloud.gateway.routes[0].filters:
  - name: RateLimit
    args:
      redis-rate-limiter.replenishRate: 10
      redis-rate-limiter.burstCapacity: 20

五、跨域配置

@Configuration
public class CorsConfig {
    @Bean
    public CorsWebFilter corsWebFilter() {
        CorsConfiguration config = new CorsConfiguration();
        config.addAllowedOrigin("*");
        config.addAllowedHeader("*");
        config.addAllowedMethod("*");
        config.setAllowCredentials(true);

        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
        source.registerCorsConfiguration("/**", config);
        return new CorsWebFilter(source);
    }
}

六、网关 vs Nginx

# Nginx：反向代理 + 负载均衡
# 适合：静态资源、SSL 终止、四层/七层负载均衡

# Spring Cloud Gateway：业务网关
# 适合：动态路由、JWT 鉴权、限流、熔断、灰度发布

# 生产推荐：Nginx（前置）+ Gateway（后置）
# 请求链路：Client → Nginx → Gateway → Microservice

总结

Spring Cloud Gateway 是微服务架构的统一入口。核心要点：基于 WebFlux 高性能非阻塞、断言灵活匹配路由、全局过滤器实现统一鉴权、配合 Nginx 构建多层网关架构。

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文章摘自：https://www.cnblogs.com/czlws/p/19826872/spring-cloud-gateway-microservice-api