如何在Angular中使用外部类？

export class ExternalClass {
  private name: string;
  
  constructor(name: string) {
    this.name = name;
  }
  
  public getName(): string {
    return this.name;
  }
}

import { Component } from '@angular/core';
import { ExternalClass } from './external-class';

@Component({
  selector: 'app-my-component',
  template: `
    <h1>{{ externalClassInstance.getName() }}</h1>
  `
})
export class MyComponent {
  public externalClassInstance: ExternalClass;
  
  constructor() {
    this.externalClassInstance = new ExternalClass('John');
  }
}