聊聊Spring Cloud Gateway 动态路由及通过Apollo的实现

spring:
  cloud:
    gateway:
      routes:
        - id: test
          predicates:
            - Path=/ms/test/*
          filters:
            - StripPrefix=2
          uri: http://localhost:9000

@Bean
    public RouteLocator routeLocator(RouteLocatorBuilder builder) {
        return builder.routes()
                .route(r -> r.path("/ms/test/**")
                .filters(f -> f.stripPrefix(2))
                .uri("http://localhost:9000"))
                .build();
    }

@Component
@Slf4j
public class GatewayPropertiesRefresher implements ApplicationContextAware, ApplicationEventPublisherAware {

  private static final String ID_PATTERN = "spring\\.cloud\\.gateway\\.routes\\[\\d+\\]\\.id";

  private static final String DEFAULT_FILTER_PATTERN = "spring\\.cloud\\.gateway\\.default-filters\\[\\d+\\]\\.name";

  private ApplicationContext applicationContext;

  private ApplicationEventPublisher publisher;

  @Autowired
  private GatewayProperties gatewayProperties;

  @Override
  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    this.applicationContext = applicationContext;
  }

  @Override
  public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
    this.publisher = applicationEventPublisher;
  }

  @ApolloConfigChangeListener(value = "route.yml",interestedKeyPrefixes = "spring.cloud.gateway.")
  public void onChange(ConfigChangeEvent changeEvent) {
    refreshGatewayProperties(changeEvent);
  }

  /***
   * 刷新org.springframework.cloud.gateway.config.PropertiesRouteDefinitionLocator中定义的routes
   *
   * @param changeEvent
   * @return void
   * @author ksewen
   * @date 2019/5/21 2:13 PM
   */
  private void refreshGatewayProperties(ConfigChangeEvent changeEvent) {
    log.info("Refreshing GatewayProperties!");
    preDestroyGatewayProperties(changeEvent);
    this.applicationContext.publishEvent(new EnvironmentChangeEvent(changeEvent.changedKeys()));
    refreshGatewayRouteDefinition();
    log.info("GatewayProperties refreshed!");
  }

  /***
   * GatewayProperties没有@PreDestroy和destroy方法
   * org.springframework.cloud.context.properties.ConfigurationPropertiesRebinder#rebind(java.lang.String)中destroyBean时不会销毁当前对象
   * 如果把spring.cloud.gateway.前缀的配置项全部删除（例如需要动态删除最后一个路由的场景），initializeBean时也无法创建新的bean，则return当前bean
   * 若仍保留有spring.cloud.gateway.routes[n]或spring.cloud.gateway.default-filters[n]等配置，initializeBean时会注入新的属性替换已有的bean
   * 这个方法提供了类似@PreDestroy的操作，根据配置文件的实际情况把org.springframework.cloud.gateway.config.GatewayProperties#routes
   * 和org.springframework.cloud.gateway.config.GatewayProperties#defaultFilters两个集合清空
   *
   * @param
   * @return void
   * @author ksewen
   * @date 2019/5/21 2:13 PM
   */
  private synchronized void preDestroyGatewayProperties(ConfigChangeEvent changeEvent) {
    log.info("Pre Destroy GatewayProperties!");
    final boolean needClearRoutes = this.checkNeedClear(changeEvent, ID_PATTERN, this.gatewayProperties.getRoutes()
        .size());
    if (needClearRoutes) {
      this.gatewayProperties.setRoutes(new ArrayList<>());
    }
    final boolean needClearDefaultFilters = this.checkNeedClear(changeEvent, DEFAULT_FILTER_PATTERN, this.gatewayProperties.getDefaultFilters()
        .size());
    if (needClearDefaultFilters) {
      this.gatewayProperties.setDefaultFilters(new ArrayList<>());
    }
    log.info("Pre Destroy GatewayProperties finished!");
  }

  private void refreshGatewayRouteDefinition() {
    log.info("Refreshing Gateway RouteDefinition!");
    this.publisher.publishEvent(new RefreshRoutesEvent(this));
    log.info("Gateway RouteDefinition refreshed!");
  }

  /***
   * 根据changeEvent和定义的pattern匹配key，如果所有对应PropertyChangeType为DELETED则需要清空GatewayProperties里相关集合
   *
   * @param changeEvent
   * @param pattern
   * @param existSize
   * @return boolean
   * @author ksewen
   * @date 2019/5/23 2:18 PM
   */
  private boolean checkNeedClear(ConfigChangeEvent changeEvent, String pattern, int existSize) {
    return changeEvent.changedKeys().stream().filter(key -> key.matches(pattern))
        .filter(key -> {
          ConfigChange change = changeEvent.getChange(key);
          return PropertyChangeType.DELETED.equals(change.getChangeType());
        }).count() == existSize;
  }
}

spring:
  cloud:
    gateway:
      routes:
        - id: test
          predicates:
            - Path=/ms/test/*
          filters:
            - StripPrefix=2
          uri: http://localhost:9000