因为业务需要调用接口获取的是 Base64文件流 需要提供给客户下载PDF文档
源码部分借鉴网上，具体地址忘记了。
//Base64文件流 byte[] buffer = Convert.FromBase64String(decodedString); System.IO.Stream iStream = new System.IO.MemoryStream(buffer);try{int length;long dataToRead;string filename = sn + ".pdf";//保存的文件名称dataToRead = iStream.Length;Response.Clear();Response.ClearHeaders();Response.ClearContent();Response.ContentType = "application/pdf"; //文件类型 Response.AddHeader("Content-Length", dataToRead.ToString());//添加文件长度，进而显示进度 Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));while (dataToRead > 0){if (Response.IsClientConnected){length = iStream.Read(buffer, 0, 10000);Response.OutputStream.Write(buffer, 0, length);Response.Flush();buffer = new Byte[10000];dataToRead = dataToRead - length;}else{dataToRead = -1;}}}catch (Exception ex){Response.Write("文件下载时出现错误!");}finally{if (iStream != null){iStream.Close();}//结束响应，否则将导致网页内容被输出到文件，进而文件无法打开 Response.Flush();Response.End();}
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