我如何在angular 7中打开一个模式而不使用按钮点击，

npm install @angular/material @angular/cdk @angular/animations

import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { MatDialogModule } from '@angular/material/dialog';

@NgModule({
  imports: [
    BrowserAnimationsModule,
    MatDialogModule
  ],
  ...
})
export class AppModule { }

import { Component } from '@angular/core';
import { MatDialogRef } from '@angular/material/dialog';

@Component({
  selector: 'app-modal',
  template: `
    <h1>模态框内容</h1>
    <button mat-button (click)="close()">关闭</button>
  `
})
export class ModalComponent {
  constructor(private dialogRef: MatDialogRef<ModalComponent>) {}

  close(): void {
    this.dialogRef.close();
  }
}

import { Component } from '@angular/core';
import { MatDialog } from '@angular/material/dialog';
import { ModalComponent } from './modal.component';

@Component({
  selector: 'app-my-component',
  template: `
    <button mat-button (click)="openModal()">打开模态框</button>
  `
})
export class MyComponent {
  constructor(private dialog: MatDialog) {}

  openModal(): void {
    const dialogRef = this.dialog.open(ModalComponent);

    dialogRef.afterClosed().subscribe(result => {
      console.log('模态框已关闭');
    });
  }
}