如何使用反应式表单验证禁用的控件(不触发验证)

import { Component } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';

@Component({
  selector: 'app-form',
  templateUrl: './form.component.html',
  styleUrls: ['./form.component.css']
})
export class FormComponent {
  form: FormGroup;

  constructor() {
    this.form = new FormGroup({
      username: new FormControl({ value: '', disabled: true }, Validators.required),
      // 其他表单控件...
    });
  }

  onSubmit() {
    if (this.form.valid) {
      // 表单验证通过，执行提交操作
    }
  }
}

<form [formGroup]="form" (ngSubmit)="onSubmit()">
  <input type="text" formControlName="username" [disabled]="true">
  <div *ngIf="form.get('username').invalid && form.get('username').touched">
    <div *ngIf="form.get('username').errors.required">用户名是必填项。</div>
  </div>
  <!-- 其他表单控件... -->
  <button type="submit">提交</button>
</form>