SpringCloud Zuul（九）之路由自动刷新原理

心已赠人 2022-10-28 00:47 230阅读 0赞

### 一、现象 ###

发布新服务，然后在数据库配置了路由，使用服务路径访问404。然后重新发布新的服务，就可以继续访问得到

（1）配置了路由第一次访问

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21vYWt1bg_size_16_color_FFFFFF_t_70][]

（2）重新发布后访问

![20210205000450386.png][]

### 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);
        }
    
        @Override
        public void refresh() {
            doRefresh();
        }
    
        @Override
        protected Map<String, ZuulProperties.ZuulRoute> locateRoutes() {
    
            //默认从配置文件中加载路由信息
            //return super.locateRoutes());
    
            //定制路由, 可以使用db的配置管理进行路由
            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 ZuulRefreshListener
    			implements ApplicationListener<ApplicationEvent> {
    
    		@Autowired
    		private ZuulHandlerMapping zuulHandlerMapping;
    
    		private HeartbeatMonitor heartbeatMonitor = new HeartbeatMonitor();
    
    		@Override
    		public 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）发现ApplicationEvent

@Override
    		public 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());
    			}
    		}

其中的实例注册事件InstanceRegisteredEvent会触发刷新路由。

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L21vYWt1bg_size_16_color_FFFFFF_t_70]: /images/20221024/6a5e9c63b242417facf75e8f373be852.png
[20210205000450386.png]: /images/20221024/6d6f867e70714fd29e2dd3bcd0688ede.png