如何在angular 6中发送分块请求？

import { HttpClient, HttpHeaders } from '@angular/common/http';
import { Observable } from 'rxjs';

constructor(private http: HttpClient) { }

sendChunkedRequest(file: File): Observable<any> {
  const chunkSize = 1024 * 1024; // 每个块的大小（这里设置为1MB）
  const totalChunks = Math.ceil(file.size / chunkSize); // 总块数
  const chunks = [];

  // 将文件分割成多个块
  for (let i = 0; i < totalChunks; i++) {
    const start = i * chunkSize;
    const end = Math.min(start + chunkSize, file.size);
    const chunk = file.slice(start, end);
    chunks.push(chunk);
  }

  // 创建一个Observable来发送每个块
  return new Observable(observer => {
    let currentChunk = 0;

    const sendNextChunk = () => {
      if (currentChunk < totalChunks) {
        const formData = new FormData();
        formData.append('chunk', chunks[currentChunk]);

        // 发送块请求
        this.http.post('your-api-endpoint', formData, {
          headers: new HttpHeaders({
            'Content-Type': 'multipart/form-data'
          })
        }).subscribe(
          response => {
            observer.next(response);
            currentChunk++;
            sendNextChunk();
          },
          error => {
            observer.error(error);
          }
        );
      } else {
        observer.complete();
      }
    };

    sendNextChunk();
  });
}