Spring Cloud Gateway 过滤器

1. 内置过滤器

filters:
  - RedirectTo=302, http://baidu.com

2. 自定义 GatewayFilter Factory

application.yml 配置

spring:
  cloud:
    gateway:
      discovery:
        locator:
          enabled: true
          lower-case-service-id: true
      routes:
      - id: concrete-service=
        uri: lb://concrete-service
        predicates:
        - Path=/user/**
        filters:
          # - RedirectTo=302, http://baidu.com
          - name: CheckAuth # 过滤器名称
            args:
              name: this is my test
              enabled: true

另一种简写方式，需要重写 shortcutFieldOrder()

filters:
 - CheckAuth=this is my test, true

// 指定参数顺序和数量
@Override
public List<String> shortcutFieldOrder() {
    return Arrays.asList("name", "enabled");
}

自定义过滤器 CheckAuth

/**
 * 命名以 GatewayFilterFactory 结尾
 * 名称是 CheckAuth
 */
@Component
public class CheckAuthGatewayFilterFactory extends AbstractGatewayFilterFactory<CheckAuthGatewayFilterFactory.Config> {

    public CheckAuthGatewayFilterFactory() {
        super(Config.class);
    }

    @Override
    public GatewayFilter apply(Config config) {
        return (exchange, chain) -> {
            System.out.println("读取配置：" + config.getName());
            ServerHttpRequest request = exchange.getRequest().mutate().build();
            return chain.filter(exchange.mutate().request(request).build());
        };
    }

    // 自定义配置类
    public static class Config {
        private String name;
        private boolean enabled;
        // Getter/Setter
    }
}

GatewayFilter 类分析

public interface GatewayFilter extends ShortcutConfigurable {
  Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain);
}

// 重写 apply()
@Override
public GatewayFilter apply(Config config) {
    return new GatewayFilter() {
        @Override
        public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
            return null;
        }
    };
}

3. 全局过滤器

• 全局过滤器作用于所有的路由，可以统一处理业务需求，比如权限认证、IP访问限制
• 使用 @Order 指定顺序，数字越小，优先级越高

@Configuration
@Slf4j
public class GlobalConfiguration {

    @Bean
    @Order(0)
    public GlobalFilter first() {
        return (exchange, chain) -> {
            log.info("pre first...");
            return chain.filter(exchange).then(Mono.fromRunnable(() -> log.info("post first...")));
        };
    }

    @Bean
    @Order(1)
    public GlobalFilter second() {
        return (exchange, chain) -> {
            log.info("pre second...");
            return chain.filter(exchange).then(Mono.fromRunnable(() -> log.info("post second...")));
        };
    }
}

打印结果

2023-01-06 13:12:05.947  INFO 42296 --- [ctor-http-nio-2] c.e.c.g.config.GlobalConfiguration       : pre first...
2023-01-06 13:12:05.949  INFO 42296 --- [ctor-http-nio-2] c.e.c.g.config.GlobalConfiguration       : pre second...
2023-01-06 13:12:05.957  INFO 42296 --- [ctor-http-nio-2] c.e.c.g.config.GlobalConfiguration       : post second...
2023-01-06 13:12:05.957  INFO 42296 --- [ctor-http-nio-2] c.e.c.g.config.GlobalConfiguration       : post first...

3.1 前置全局过滤器

• 请求执行之前

@Component
@Slf4j
public class PreGlobalFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        HttpHeaders headers = exchange.getRequest().getHeaders();
        MultiValueMap<String, String> queryParams = exchange.getRequest().getQueryParams();
        log.info(JSON.toJSONString(queryParams));
        return chain.filter(exchange);
    }

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

3.2 后置全局过滤器

• 在调用链执行完成之后执行

@Component
@Slf4j
public class PostGlobalFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        return chain.filter(exchange)
                .then(Mono.fromRunnable(() -> log.info("post run...")));
    }

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

3.3 前置过滤器和后置过滤器组合在一起

@Component
@Slf4j
public class PostGlobalFilter implements GlobalFilter, Ordered {

    @Override
    public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
        MultiValueMap<String, String> queryParams = exchange.getRequest().getQueryParams();
        if (queryParams.containsKey("message")) {
            log.info("前置处理");
            ServerHttpResponse response = exchange.getResponse();
            DataBuffer dataBuffer = response.bufferFactory().wrap("pre-run".getBytes(StandardCharsets.UTF_8));
            return response.writeWith(Mono.just(dataBuffer));
        }

        return chain.filter(exchange)
                .then(Mono.fromRunnable(() -> log.info("post run...")));
    }

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

请求地址 http://localhost:8010/user/query?message=Hello