如何将文件加载到angular组件中并通过http发送

<input type="file" (change)="onFileSelected($event)">

selectedFile: File;

onFileSelected(event: any) {
  this.selectedFile = event.target.files[0];
}

import { HttpClient } from '@angular/common/http';

constructor(private http: HttpClient) {}

onUpload() {
  const formData = new FormData();
  formData.append('file', this.selectedFile);

  this.http.post('http://example.com/upload', formData)
    .subscribe(response => {
      console.log('File uploaded successfully');
    }, error => {
      console.error('Error uploading file:', error);
    });
}

<button (click)="onUpload()">Upload</button>