Spring Cloud Gateway动态路由Apollo实现详解

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