1.RouteLocation详解

1.1 RouteLocation关系

继承、组合关系见下图

1.1.1 SimpleRouteLocator详解

SimpleRouteLocator代码相对比较简单，主要看下LocateRoutes方法，根据配置文件（application.yaml）注入到zuulProperties，转换成LinkedHashMap<String, ZuulRoute>,所以SimpleRouteLocator的路由数据是读取配置文件中的数据。

protected Map<String, ZuulRoute> locateRoutes() {
		LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<String, ZuulRoute>();
		for (ZuulRoute route : this.properties.getRoutes().values()) {
			routesMap.put(route.getPath(), route);
		}
		return routesMap;
	}

1.1.2 DiscoveryClientRouteLocator详解

此路由的主要作用是去注册中心获取service列表，并实现了RefreshableRouteLocator的refresh接口，默认每30s刷新注册中心数据。可以看到其实现逻辑是通过discovery去查询注册中心的微服务注册数据。

	@Override
	protected LinkedHashMap<String, ZuulRoute> locateRoutes() {
		LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<String, ZuulRoute>();
		routesMap.putAll(super.locateRoutes());
		if (this.discovery != null) {
			Map<String, ZuulRoute> staticServices = new LinkedHashMap<String, ZuulRoute>();
			for (ZuulRoute route : routesMap.values()) {
				String serviceId = route.getServiceId();
				if (serviceId == null) {
					serviceId = route.getId();
				}
				if (serviceId != null) {
					staticServices.put(serviceId, route);
				}
			}
			// Add routes for discovery services by default
			List<String> services = this.discovery.getServices();
			String[] ignored = this.properties.getIgnoredServices()
					.toArray(new String[0]);
			for (String serviceId : services) {
				// Ignore specifically ignored services and those that were manually
				// configured
				String key = "/" + mapRouteToService(serviceId) + "/**";
				if (staticServices.containsKey(serviceId)
						&& staticServices.get(serviceId).getUrl() == null) {
					// Explicitly configured with no URL, cannot be ignored
					// all static routes are already in routesMap
					// Update location using serviceId if location is null
					ZuulRoute staticRoute = staticServices.get(serviceId);
					if (!StringUtils.hasText(staticRoute.getLocation())) {
						staticRoute.setLocation(serviceId);
					}
				}
				if (!PatternMatchUtils.simpleMatch(ignored, serviceId)
						&& !routesMap.containsKey(key)) {
					// Not ignored
					routesMap.put(key, new ZuulRoute(key, serviceId));
				}
			}
		}
		if (routesMap.get(DEFAULT_ROUTE) != null) {
			ZuulRoute defaultRoute = routesMap.get(DEFAULT_ROUTE);
			// Move the defaultServiceId to the end
			routesMap.remove(DEFAULT_ROUTE);
			routesMap.put(DEFAULT_ROUTE, defaultRoute);
		}
		LinkedHashMap<String, ZuulRoute> values = new LinkedHashMap<>();
		for (Entry<String, ZuulRoute> entry : routesMap.entrySet()) {
			String path = entry.getKey();
			// Prepend with slash if not already present.
			if (!path.startsWith("/")) {
				path = "/" + path;
			}
			if (StringUtils.hasText(this.properties.getPrefix())) {
				path = this.properties.getPrefix() + path;
				if (!path.startsWith("/")) {
					path = "/" + path;
				}
			}
			values.put(path, entry.getValue());
		}
		return values;
	}

1.1.3 CompositeRouteLocator

复合路由器，主要是依赖注入了RouteLocator集合，对相关接口的实现都是遍历spring ioc容器里面存在的RouteLocator，并循环执行相对应的接口。

	@Override
	public Collection<String> getIgnoredPaths() {
		List<String> ignoredPaths = new ArrayList<>();
		for (RouteLocator locator : routeLocators) {
			ignoredPaths.addAll(locator.getIgnoredPaths());
		}
		return ignoredPaths;
	}

	@Override
	public List<Route> getRoutes() {
		List<Route> route = new ArrayList<>();
		for (RouteLocator locator : routeLocators) {
			route.addAll(locator.getRoutes());
		}
		return route;
	}

	@Override
	public Route getMatchingRoute(String path) {
		for (RouteLocator locator : routeLocators) {
			Route route = locator.getMatchingRoute(path);
			if (route != null) {
				return route;
			}
		}
		return null;
	}

	@Override
	public void refresh() {
		for (RouteLocator locator : routeLocators) {
			if (locator instanceof RefreshableRouteLocator) {
				((RefreshableRouteLocator) locator).refresh();
			}
		}
	}

1.1.4 总结

SimpleRouteLocator，DiscoveryClientRouteLocator，CompositeRouteLocator的代码比较简单，整体的逻辑还是比较复杂，设计比较巧妙，可扩展性很强，注意以下细节点：
1）SimpleRouteLocator是@EnableZuulServer注入的，DiscoveryClientRouteLocator是@EnableZuulProxy注入的。
2）SimpleRouteLocator处理的是配置文件，DiscoveryClientRouteLocator处理的是注册中心的配置信息。若需要扩展定义如定时从数据库中拉取配置信息，则需要自定义RouteLocator实现RefreshableRouteLocator
3）SimpleRouteLocator，DiscoveryClientRouteLocator的注入方式均使用的@ConditionOnMissingBean，这意味着如果是zuulProxy注入，则只会加载DiscoveryClientRouteLocator，因为DiscoveryClientRouteLocator是SimpleRouteLocator类型，这也方便自定义RouteLocator取代原RouteLocator
举例来说：@EnableZuulProxy注入，新建CustomerRouteLocator继承SimpleRouteLocator，则会加载DiscoveryClientRouteLocator，CustomerRouteLocator
若新建CustomerRouteLocator继承DiscoveryClientRouteLocator，则只会加载CustomerRouteLocator
4）CompositeRouteLocator的注入方式为@primary，所以在其他类中定义private RouteLocator routeLocator则模式加载的是CompositeRouteLocator。所以如果其他类中调用routeLocator.getRoutes()方法，则默认会循环调用所有被加载注入的RouteLocator，其他方法也一样会有相关逻辑。
5）CompositeRouteLocator的构造函数中AnnotationAwareOrderComparator.sort(rl)，表示会对RouteLocator进行排序，排序的方式是实现Order接口的getOrder（）方法。SimpleRouteLocator，DiscoveryClientRouteLocator的getOrder（）均返回0.