如何在angular 2中选择所有复选框？

<div *ngFor="let item of items">
  <input type="checkbox" [(ngModel)]="item.selected">
  {{ item.name }}
</div>

export class MyComponent {
  items = [
    { name: 'Item 1', selected: false },
    { name: 'Item 2', selected: false },
    { name: 'Item 3', selected: false }
  ];
}

<input type="checkbox" [(ngModel)]="selectAll" (ngModelChange)="selectAllItems()">

export class MyComponent {
  items = [
    { name: 'Item 1', selected: false },
    { name: 'Item 2', selected: false },
    { name: 'Item 3', selected: false }
  ];
  selectAll = false;

  selectAllItems() {
    for (let item of this.items) {
      item.selected = this.selectAll;
    }
  }
}