ng文件上传- ng-src不工作

<input type="file" (change)="onFileSelected($event)">
<button (click)="uploadFile()">上传</button>

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

@Component({
  selector: 'app-file-upload',
  templateUrl: './file-upload.component.html',
  styleUrls: ['./file-upload.component.css']
})
export class FileUploadComponent {
  selectedFile: File;

  constructor(private http: HttpClient) { }

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

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

    this.http.post('http://example.com/upload', formData)
      .subscribe(response => {
        console.log('文件上传成功');
      }, error => {
        console.error('文件上传失败');
      });
  }
}