Zuul- 路由加载

Zuul- 启动，咱们提到了zuulRefreshRoutesListener，能够用来动态刷新路由，咱们看看他是怎么加载的。
一下这几个事件会触发reset方法。

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());
    }
}

DiscoveryClientRouteLocator#locateRoutes

追着这个方法下去，咱们最后会到DiscoveryClientRouteLocator#locateRoutes方法。这里主要是获取两个地方的配置，一个是咱们的配置文件，一个是Eureka的注册表信息。

protected LinkedHashMap<String, ZuulRoute> locateRoutes() {
    LinkedHashMap<String, ZuulRoute> routesMap = new LinkedHashMap<>();
    // 先调用父类的方法，
    routesMap.putAll(super.locateRoutes());
    if (this.discovery != null) {
        Map<String, ZuulRoute> staticServices = new LinkedHashMap<>();
        for (ZuulRoute route : routesMap.values()) {
            String serviceId = route.getServiceId();
            if (serviceId == null) {
                serviceId = route.getId();
            }
            if (serviceId != null) {
                staticServices.put(serviceId, route);
            }
        }
        // 从Eureka获取注册表信息
        List<String> services = this.discovery.getServices();
        // 是否有过滤的条件
        String[] ignored = this.properties.getIgnoredServices()
                .toArray(new String[0]);
        for (String serviceId : services) {
            String key = "/" + mapRouteToService(serviceId) + "/**";
            if (staticServices.containsKey(serviceId)
                    && staticServices.get(serviceId).getUrl() == null) {
                ZuulRoute staticRoute = staticServices.get(serviceId);
                if (!StringUtils.hasText(staticRoute.getLocation())) {
                    staticRoute.setLocation(serviceId);
                }
            }
            if (!PatternMatchUtils.simpleMatch(ignored, serviceId)
                    && !routesMap.containsKey(key)) {
                routesMap.put(key, new ZuulRoute(key, serviceId));
            }
        }
    }
    if (routesMap.get(DEFAULT_ROUTE) != null) {
        ZuulRoute defaultRoute = routesMap.get(DEFAULT_ROUTE);
        routesMap.remove(DEFAULT_ROUTE);
        routesMap.put(DEFAULT_ROUTE, defaultRoute);
    }
    // 返回本地配置+Eureka未过滤的注册表
    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;
}

Eureka的注册表有个IgnoredServices配置，咱们能够对他进行过滤，这样避免服务名称直接暴露出来。

zuul:
  ignoredServices: '*'
  routes:
    users: /myusers/**

SimpleRouteLocator#locateRoutes

读取本地的时候，直接从ZuulProperties取值。

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

ZuulProperties被加载的时候，因为有一个@PostConstruct注解，他会调用init方法。在这里会根据咱们的配置信息进行赋值serviceId、id、path。

@PostConstruct
public void init() {
    for (Entry<String, ZuulRoute> entry : this.routes.entrySet()) {
        ZuulRoute value = entry.getValue();
        if (!StringUtils.hasText(value.getLocation())) {
            value.serviceId = entry.getKey();
        }
        if (!StringUtils.hasText(value.getId())) {
            value.id = entry.getKey();
        }
        if (!StringUtils.hasText(value.getPath())) {
            value.path = "/" + entry.getKey() + "/**";
        }
    }
}

流程图

动态路由

咱们知道了何时触发路由的从新加载，那咱们能够在路由信息改变的时候，就调用触发他的条件，好比RoutesRefreshedEvent。
咱们知道了他的加载流程，先本地再注册中心，咱们也能够自定义本身的加载流程，好比先本地，再数据库，数据库变动，就触发RoutesRefreshedEvent时间，达到动态路由的目的。