基于Spring Cloud Gateway + Nacos实现动态路由热更新

Nacos 控制台修改 yichen-gateway.yaml
  → NacosConfigService 长轮询感知（秒级）
  → NacosContextRefresher 发布 RefreshEvent
  → Spring Cloud RefreshEventListener 调 ContextRefresher.refresh()
      ├─ refreshEnvironment()：重拉 ConfigData，发布 EnvironmentChangeEvent
      │     └─ ConfigurationPropertiesRebinder 重新绑定 @ConfigurationProperties Bean
      └─ scope.refreshAll()：无条件发布 RefreshScopeRefreshedEvent
            └─ SCG 内置 RouteRefreshListener 监听此事件 → 发布 RefreshRoutesEvent
  → CachingRouteLocator 收到 RefreshRoutesEvent → 清缓存、重建路由

@Override
public void refreshAll() {
    super.destroy();
    this.context.publishEvent(new RefreshScopeRefreshedEvent());  // 无条件
}

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cloud.context.environment.EnvironmentChangeEvent;
import org.springframework.cloud.gateway.event.RefreshRoutesEvent;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.event.EventListener;
import org.springframework.stereotype.Component;

import java.util.Set;

/**
 * Nacos 配置变更 → Gateway 路由缓存重建桥接器
 *
 * <p>框架内置的 RouteRefreshListener 监听 RefreshScopeRefreshedEvent（ContextRefresher.refresh()
 * 中 scope.refreshAll() 无条件发布），任何配置变更都会触发路由缓存重建——该内置链路无过滤、
 * 且静默无日志。本桥接器的前缀过滤不改变上述框架行为，其真实价值在于：
 * ① 可观测性；② 兜底 SCA 链路差异；③ 显式确定性。</p>
 */
@Component
public class GatewayRouteRefreshBridge {

    private static final Logger log = LoggerFactory.getLogger(GatewayRouteRefreshBridge.class);

    private static final String GATEWAY_CONFIG_PREFIX = "spring.cloud.gateway";

    private final ApplicationEventPublisher publisher;

    public GatewayRouteRefreshBridge(ApplicationEventPublisher publisher) {
        this.publisher = publisher;
    }

    @EventListener(EnvironmentChangeEvent.class)
    public void onEnvironmentChange(EnvironmentChangeEvent event) {
        Set<String> keys = event.getKeys();
        if (keys == null || keys.isEmpty()) {
            return;
        }
        boolean hit = keys.stream().anyMatch(k -> k != null && k.startsWith(GATEWAY_CONFIG_PREFIX));
        if (hit) {
            log.info("检测到网关配置变更，发布 RefreshRoutesEvent 重建路由缓存: keys={}", keys);
            publisher.publishEvent(new RefreshRoutesEvent(this));
        }
    }
}

GatewayRouteRefreshBridge - 检测到网关配置变更，发布 RefreshRoutesEvent 重建路由缓存:
    keys=[spring.cloud.gateway.routes[8].uri, spring.cloud.gateway.routes[8].predicates[0]]
RefreshEventListener - Refresh keys changed: [spring.cloud.gateway.routes[8].uri, ...]

WARN GatewayServerWebfluxPropertiesMigrationListener -
The use of configuration keys that have been renamed was found in the environment:
Property source 'DEFAULT_GROUP@yichen-gateway.yaml':
    Key: spring.cloud.gateway.routes[8].uri
        Replacement: spring.cloud.gateway.server.webflux.routes[8].uri
    ...
Each configuration key has been temporarily mapped to its replacement for your convenience.

启动时：
  Environment 里只有旧 key
  → MigrationListener 把旧 key 值映射到新 key 位置（快照）
  → GatewayProperties 绑新前缀读到快照 ✓

运行时 Nacos 改旧 key：
  → Environment 里旧 key 更新了
  → 但 MigrationListener 不会再触发（它只监听 ApplicationPreparedEvent）
  → 新 key 位置的值仍是启动快照
  → GatewayProperties rebind 后读到的还是旧值 ✗

spring:
  cloud:
    gateway:
      server:
        webflux:
          discovery:
            locator:
              enabled: false
              lower-case-service-id: true
          globalcors:
            cors-configurations:
              '[/**]':
                ...
          routes:
            - id: xxx
              uri: lb://xxx
              ...
          default-filters:
            - AddResponseHeader=...

1. 同步 Nacos 配置（先改再重启）
2. 重启 Pod
3. 启动日志确认：无 MigrationListener 警告、无 no longer supported
4. Nacos 改一条路由
5. 观察桥接类日志 + 请求验证

default-filters:
  - AddResponseHeader=X-Gateway-Start-Time, ${random.long}

<spring-boot.version>3.5.0</spring-boot.version>
<spring-cloud.version>2025.0.0</spring-cloud.version>
<spring-cloud-alibaba.version>2025.0.0.0</spring-cloud-alibaba.version>
<spring-cloud-gateway.version>4.3</spring-cloud-gateway.version>