阻止表单输入焦点上的mat-menu关闭

<button [matMenuTriggerFor]="menu">打开菜单</button>
<mat-menu #menu="matMenu">
  <!-- 菜单内容 -->
</mat-menu>

import { Component, ViewChild, ElementRef } from '@angular/core';

@Component({
  selector: 'app-example',
  templateUrl: './example.component.html',
  styleUrls: ['./example.component.css']
})
export class ExampleComponent {
  @ViewChild('menuTrigger') menuTrigger: ElementRef;

  onInputFocus() {
    // 阻止菜单关闭
    this.menuTrigger['_elementRef'].nativeElement.blur();
  }
}

<input (focus)="onInputFocus()" />