错误无法加载PDF文档。 （Angular5）

Question

我试图从Web API获取PDF文档，并希望在Angular App中显示。获取“无法加载PDF文档错误”。

请按照我的代码：

我的服务

public download_pdf(id: string): Observable<any> {
        let params = new URLSearchParams();
        let headers = new Headers();
        headers.append('x-access-token', this.auth.getCurrentUser().token);
        headers.append('id', id);
        return this.http.get(Api.getUrl(Api.URLS.download_pdf), {
          headers: headers,
          responseType: ResponseContentType.ArrayBuffer,

        }).map(
          response => (<Response>response).blob())
    }

我的组件

  downloadFile2(id) {
    this.ws.download_pdf(id).subscribe(
      (response) => {
        let mediaType = 'application/pdf';
        let blob = new Blob([response._body], {type: mediaType});
        let filename = 'test.pdf';
        FileSaver.saveAs(blob, filename);
      });
  }

Template.html

  <button>
   <i class="fa fa-save" aria-hidden="true"(click)="downloadFile2(item.id)"></i>
  </button>

结果是：下载一个test.pdf - >错误无法加载PDF文档。

Answer 1

请按照以下步骤解决此问题。

步骤1.将您的字节数组转换为API中的base64字符串，如下所示

[HttpGet("Downloadpdf/{SessionKey}")]
        public IActionResult Downloadpdf(string SessionKey)
        {
            Byte[] pdf = null;
            try
            {
                pdf = PDFService.Downloadpdf(SessionKey);//Here you need to modify and get byte array like byte[]
                string pdfBase64 = Convert.ToBase64String(pdf);
                return Ok(pdfBase64);
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

步骤2.添加以下函数以在.ts文件中从base64字符串转换为ArrayBuffer

base64ToArrayBuffer(base64:any):ArrayBuffer {
      var binary_string =  window.atob(base64);
      var len = binary_string.length;
      var bytes = new Uint8Array( len );
      for (var i = 0; i < len; i++)        {
          bytes[i] = binary_string.charCodeAt(i);
      }
      return bytes.buffer;
  }

步骤3.在自定义函数中调用step2函数以执行按钮单击事件

let sessionKey: any ="sessiontoken";
      this.pdfService.downloadpdf(sessionKey).subscribe((data: any) => {
        var byteArray = this.base64ToArrayBuffer(data);
        let blob: any = new Blob([byteArray], { type: 'application/octet-stream' });
        saveAs(blob, 'Report.pdf',true);
      },
      (error: HttpErrorResponse) => {
        console.log(error)
    });