在angular dart中，如何使上/下箭头键在列表中导航？

import 'dart:html';
import 'package:angular/angular.dart';

@Component(
  selector: 'my-component',
  template: '''
    <ul>
      <li *ngFor="let item of items; let i = index" [ngClass]="{'selected': i == currentIndex}">
        {{item}}
      </li>
    </ul>
  ''',
  styles: ['.selected { background-color: yellow; }'],
)
class MyComponent {
  List<String> items = ['Item 1', 'Item 2', 'Item 3'];
  int currentIndex = 0;

  @HostListener('keydown')
  void onKeyDown(KeyboardEvent event) {
    if (event.keyCode == KeyCode.UP && currentIndex > 0) {
      currentIndex--;
    } else if (event.keyCode == KeyCode.DOWN && currentIndex < items.length - 1) {
      currentIndex++;
    }
  }
}