使用路由器链接创建多级菜单，该菜单在单击angular 2中的任何路由项目后不会关闭

<ul>
  <li *ngFor="let item of menuItems">
    <a [routerLink]="item.route">{{ item.label }}</a>
    <ul *ngIf="item.children">
      <li *ngFor="let childItem of item.children">
        <a [routerLink]="childItem.route">{{ childItem.label }}</a>
      </li>
    </ul>
  </li>
</ul>

export class MenuComponent implements OnInit {
  menuItems: MenuItem[];

  ngOnInit() {
    this.menuItems = [
      {
        label: '菜单项1',
        route: '/menu1',
        children: [
          {
            label: '子菜单项1',
            route: '/menu1/child1'
          },
          {
            label: '子菜单项2',
            route: '/menu1/child2'
          }
        ]
      },
      {
        label: '菜单项2',
        route: '/menu2'
      }
    ];
  }
}

const routes: Routes = [
  { path: 'menu1', component: Menu1Component },
  { path: 'menu1/child1', component: Child1Component },
  { path: 'menu1/child2', component: Child2Component },
  { path: 'menu2', component: Menu2Component }
];

@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule]
})
export class AppRoutingModule { }