Angular2 版本2.3之后提供了一個實驗性的class: RouteReuseStrategy
可以用于暫存路由的狀態，在重新跳轉回該路由時恢復狀態（不用重新初始化component)。

定義：

class RouteReuseStrategy {
[shouldDetach
](https://angular.io/docs/ts/latest/api/router/index/RouteReuseStrategy-class.html#shouldDetach-anchor)(route: ActivatedRouteSnapshot) : boolean

[store
](https://angular.io/docs/ts/latest/api/router/index/RouteReuseStrategy-class.html#store-anchor)(route: ActivatedRouteSnapshot, handle: DetachedRouteHandle) : void

[shouldAttach
](https://angular.io/docs/ts/latest/api/router/index/RouteReuseStrategy-class.html#shouldAttach-anchor)(route: ActivatedRouteSnapshot) : boolean

[retrieve
](https://angular.io/docs/ts/latest/api/router/index/RouteReuseStrategy-class.html#retrieve-anchor)(route: ActivatedRouteSnapshot) : DetachedRouteHandle

[shouldReuseRoute
](https://angular.io/docs/ts/latest/api/router/index/RouteReuseStrategy-class.html#shouldReuseRoute-anchor)(future: ActivatedRouteSnapshot, curr: ActivatedRouteSnapshot) : boolean

}

說明

shouldDetach(route: ActivatedRouteSnapshot) : boolean

決定是否將當前的路由進行分離并暫存。

store(route: ActivatedRouteSnapshot, handle: DetachedRouteHandle) : void

存儲分離出的路由

shouldAttach(route: ActivatedRouteSnapshot) : boolean

決定當前的路由是否還原

retrieve(route: ActivatedRouteSnapshot) : DetachedRouteHandle

取得之前暫存的路由

shouldReuseRoute(future: ActivatedRouteSnapshot, curr: ActivatedRouteSnapshot) : boolean

決定是否重用路由

案例

export class CustomReuseStrategy implements RouteReuseStrategy {

    handlers: {[key: string]: DetachedRouteHandle} = {};

    shouldDetach(route: ActivatedRouteSnapshot): boolean {
        console.debug('CustomReuseStrategy:shouldDetach', route);
        return true;
    }

    store(route: ActivatedRouteSnapshot, handle: DetachedRouteHandle): void {
        console.debug('CustomReuseStrategy:store', route, handle);
        this.handlers[route.routeConfig.path] = handle;
    }

    shouldAttach(route: ActivatedRouteSnapshot): boolean {
        console.debug('CustomReuseStrategy:shouldAttach', route);
        return !!route.routeConfig && !!this.handlers[route.routeConfig.path];
    }

    retrieve(route: ActivatedRouteSnapshot): DetachedRouteHandle {
        console.debug('CustomReuseStrategy:retrieve', route);
        return this.handlers[route.routeConfig.path];//從暫存處取回
    }

    shouldReuseRoute(future: ActivatedRouteSnapshot, curr: ActivatedRouteSnapshot): boolean {
        //在此處可以取得跳轉前和跳轉后的路由路徑
        console.debug('CustomReuseStrategy:shouldReuseRoute', future, curr);
        return future.routeConfig === curr.routeConfig;
    }
}

Reference：
https://angular.io/docs/ts/latest/api/router/index/RouteReuseStrategy-class.html
https://www.softwarearchitekt.at/post/2016/12/02/sticky-routes-in-angular-2-3-with-routereusestrategy.aspx