Question

我正在尝试使用以下代码从谷歌驱动器下载文件：

     public static Boolean downloadFile(string downloadurl, string _saveTo)
        {

            if (!String.IsNullOrEmpty(downloadurl))
            {
                try
                {
                  var x = service.HttpClient.GetByteArrayAsync(downloadurl);
                    byte[] arrBytes = x.Result;
                    System.IO.File.WriteAllBytes(_saveTo, arrBytes);
                    return true;
                }
                catch (Exception e)
                {
                    Console.WriteLine("An error occurred: " + e.Message);
                    return false;
                }
            }
            else
            {
                // The file doesn't have any content stored on Drive.
                return false;
            }
        }

调试上面的代码抛出异常如下：

?service.HttpClient.GetByteArrayAsync(downloadurl)
Id = 10, Status = WaitingForActivation, Method = "{null}", Result = "{Not yet computed}"
    AsyncState: null
    CancellationPending: false
    CreationOptions: None
    Exception: null
    Id: 10
    Result: null
    Status: WaitingForActivation

我正在尝试通过使用Google API控制台创建的服务帐户执行此操作。

，例外情况如下：

System.NullReferenceException was caught
  HResult=-2147467261
  Message=Object reference not set to an instance of an object.
  Source=System.Net.Http
  StackTrace:
       at System.Net.Http.Headers.HttpRequestHeaders.AddHeaders(HttpHeaders sourceHeaders)
       at System.Net.Http.HttpClient.PrepareRequestMessage(HttpRequestMessage request)
       at System.Net.Http.HttpClient.SendAsync(HttpRequestMessage request, HttpCompletionOption completionOption, CancellationToken cancellationToken)
       at System.Net.Http.HttpClient.GetAsync(Uri requestUri, HttpCompletionOption completionOption, CancellationToken cancellationToken)
       at System.Net.Http.HttpClient.GetContentAsync[T](Uri requestUri, HttpCompletionOption completionOption, T defaultValue, Func`2 readAs)
       at System.Net.Http.HttpClient.GetByteArrayAsync(Uri requestUri)
       at System.Net.Http.HttpClient.GetByteArrayAsync(String requestUri)

Answer 1

你可以试试这个。
link

using Google.Apis.Authentication;
    using Google.Apis.Drive.v2;
    using Google.Apis.Drive.v2.Data;

    using System.Net;

    public class MyClass {

      public static System.IO.Stream DownloadFile(
          IAuthenticator authenticator, File file) {
        if (!String.IsNullOrEmpty(file.DownloadUrl)) {
          try {
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(
                new Uri(file.DownloadUrl));
            authenticator.ApplyAuthenticationToRequest(request);
            HttpWebResponse response = (HttpWebResponse) request.GetResponse();
            if (response.StatusCode == HttpStatusCode.OK) {
              return response.GetResponseStream();
            } else {
              Console.WriteLine(
                  "An error occurred: " + response.StatusDescription);
              return null;
            }
          } catch (Exception e) {
            Console.WriteLine("An error occurred: " + e.Message);
            return null;
          }
        } else {
          // The file doesn't have any content stored on Drive.
          return null;
        }
      }
    }

使用asp.net从谷歌驱动器下载文件

1 个答案: