使用Angular构建上传

        const inputEl = this.el.nativeElement.firstElementChild;
        if (inputEl.files.length === 0) {
            return;
        };
        const files: FileList = inputEl.files;
        for (let i = 0; i < files.length; i++) {
            const formData = new FormData();
            formData.append('file', files[i]);
            formData.append('key', files[i].name);
            formData.append('token', this.uptoken);
            this.loading = true;
            const request = new HttpRequest(
                'POST', this.upHost , formData,
                {reportProgress: true});
            this.http.request(request)
                .retry(3)
                .subscribe(
                    event => {
                        if (event.type === HttpEventType.UploadProgress) {
                            this.loading = true;
                            this.percentDone = Math.round(100 * event.loaded / event.total);
                            this.progress = `File is ${this.percentDone}% uploaded.`;
                        } else if (event instanceof HttpResponse) {
                            this.progress = `${event.body['key']} is uploaded`;}});
            this.loading = false;
        }
    }