最终实例demo
 app-component.ts
import { Component } from '@angular/core';
import { FormBuilder, FormGroup, Validators...],
      lastName: ['Jones', Validators.required],
      about: []
    });
  }
  submit() {
    if (...],
  email: ['', [Validators.required, Validators.email]],
  age: ['', Validators.required],
  ...
})...;
// 也可以写成
this.personForm = new FormGroup({
  username:  new FormControl('',  Validators.required),...email:  new FormControl('', Validators.required),
});
表单元素上面不要同时出现formControlName和ngModel
 如 <input