在angular 2中上传文件

<form (submit)="uploadFile($event)">
  <input type="file" (change)="onFileSelected($event)">
  <button type="submit">上传文件</button>
</form>

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(event: any) {
    event.preventDefault();

    if (this.selectedFile) {
      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：', error);
        });
    }
  }
}