一、現象

發布新服務，然后在數據庫配置了路由，使用服務路徑訪問404。然后重新發布新的服務，就可以繼續訪問得到

（1）配置了路由第一次訪問

（2）重新發布后訪問

?

二、分析

（1）查找RefreshableRouteLocator .refresh方法

@Component public class NacosRouteLocator extends SimpleRouteLocator implements RefreshableRouteLocator {public NacosRouteLocator(ServerProperties serverProperties, ZuulProperties properties) {super(serverProperties.getServlet().getContextPath(), properties);}@Overridepublic void refresh() {doRefresh();}@Overrideprotected Map<String, ZuulProperties.ZuulRoute> locateRoutes() {//默認從配置文件中加載路由信息//return super.locateRoutes());//定制路由, 可以使用db的配置管理進行路由Map<String, ZuulProperties.ZuulRoute> routesMap = DbUtils.loadRoutes();return routesMap;}}

（2）ZuulHandlerMapping.setDirty方法

public class ZuulHandlerMapping extends AbstractUrlHandlerMapping {public void setDirty(boolean dirty) {this.dirty = dirty;if (this.routeLocator instanceof RefreshableRouteLocator) {((RefreshableRouteLocator) this.routeLocator).refresh();}} }

（3）ZuulRefreshListener.reset方法

private static class ZuulRefreshListenerimplements ApplicationListener<ApplicationEvent> {@Autowiredprivate ZuulHandlerMapping zuulHandlerMapping;private HeartbeatMonitor heartbeatMonitor = new HeartbeatMonitor();@Overridepublic void onApplicationEvent(ApplicationEvent event) {if (event instanceof ContextRefreshedEvent|| event instanceof RefreshScopeRefreshedEvent|| event instanceof RoutesRefreshedEvent|| event instanceof InstanceRegisteredEvent) {reset();}else if (event instanceof ParentHeartbeatEvent) {ParentHeartbeatEvent e = (ParentHeartbeatEvent) event;resetIfNeeded(e.getValue());}else if (event instanceof HeartbeatEvent) {HeartbeatEvent e = (HeartbeatEvent) event;resetIfNeeded(e.getValue());}}private void resetIfNeeded(Object value) {if (this.heartbeatMonitor.update(value)) {reset();}}private void reset() {this.zuulHandlerMapping.setDirty(true);}}

（4）發現ApplicationEvent

@Overridepublic void onApplicationEvent(ApplicationEvent event) {if (event instanceof ContextRefreshedEvent|| event instanceof RefreshScopeRefreshedEvent|| event instanceof RoutesRefreshedEvent|| event instanceof InstanceRegisteredEvent) {reset();}else if (event instanceof ParentHeartbeatEvent) {ParentHeartbeatEvent e = (ParentHeartbeatEvent) event;resetIfNeeded(e.getValue());}else if (event instanceof HeartbeatEvent) {HeartbeatEvent e = (HeartbeatEvent) event;resetIfNeeded(e.getValue());}}

其中的實例注冊事件InstanceRegisteredEvent會觸發刷新路由。

總結

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