无法从Google云端硬盘下载PDF文件

Question

当我尝试从Google云端硬盘帐户下载pdf文件时，出现500错误，当尝试下载docx文件时，该文件正在下载但出现损坏的文件。

这是我的代码：

<script type="text/javascript">

    // The Browser API key obtained from the Google API Console.
    // Replace with your own Browser API key, or your own key.
    var developerKey = 'MY_API_KEY';

    // The Client ID obtained from the Google API Console. Replace with your own Client ID.
    var clientId = "MY_CLIENT_ID.apps.googleusercontent.com"

    // Replace with your own project number from console.developers.google.com.
    // See "Project number" under "IAM & Admin" > "Settings"
    var appId = "MY_APP_ID";

    // Scope to use to access user's Drive items.
    var scope = ['https://www.googleapis.com/auth/drive'];

    var pickerApiLoaded = false;
    var oauthToken;

    // Use the Google API Loader script to load the google.picker script.
    function loadPicker() {
      gapi.load('auth', {'callback': onAuthApiLoad});
      gapi.load('picker', {'callback': onPickerApiLoad});
    }

    function onAuthApiLoad() {
      window.gapi.auth.authorize(
          {
            'client_id': clientId,
            'scope': scope,
            'immediate': false
          },
          handleAuthResult);
    }

    function onPickerApiLoad() {
      pickerApiLoaded = true;
      createPicker();
    }

    function handleAuthResult(authResult) {
      if (authResult && !authResult.error) {
        oauthToken = authResult.access_token;
        createPicker();
      }
    }

    // Create and render a Picker object for searching images.
    function createPicker() {
      if (pickerApiLoaded && oauthToken) {
        var view = new google.picker.View(google.picker.ViewId.PDFS);
        view.setMimeTypes("application/pdf");
        var picker = new google.picker.PickerBuilder()
            .enableFeature(google.picker.Feature.NAV_HIDDEN)
            .enableFeature(google.picker.Feature.MULTISELECT_ENABLED)
            .setAppId(appId)
            .setOAuthToken(oauthToken)
            .addView(view)
            .addView(new google.picker.DocsUploadView())
            .setDeveloperKey(developerKey)
            .setCallback(pickerCallback)
            .build();
         picker.setVisible(true);
      }
    }

    // A simple callback implementation.
    function pickerCallback(data) {
      if (data.action == google.picker.Action.PICKED) {
        var fileId = data.docs[0].id;
        var url= data.docs[0].webContentLink;
        var filename = data.docs[0].originalFilename;
        $.ajax({
                    type: "POST",
                    url: "test.aspx/GetDriveFile",
                    data: JSON.stringify({
                        FileName: filename, UploadUrl: url
                    }),
                    contentType: "application/json; charset=utf-8",
                    dataType: "json",
                    success: function (msg) {
                        if (msg.d == "True") {
                            alert("Success");
                        }
                    },
                    error: function (msg) {
                        alert("Failed");
                    });
      }
    }
    </script>
    <script src="https://www.google.com/jsapi?key=MY_API_KEY"></script>
    <script src="https://apis.google.com/js/client.js?onload=loadPicker"></script>

如果将选择器视图设置为以下显示的类型，则可以下载docx文件，但该文件已损坏。

var view = new google.picker.View(google.picker.ViewId.DOCUMENTS);

这是我的后端代码：

<WebMethod()>
<ScriptMethod(ResponseFormat:=ResponseFormat.Json)>
Public Shared Function GetDriveFile(ByVal FileName As String, ByVal UploadUrl As String) As String
    'https://drive.google.com/uc?export=download&id=0B0gjYWPmUtL7cDFQZG9hZWlnaW8
    Try
        Dim UploadedPath As String = HttpContext.Current.Server.MapPath("UploadedFiles/") + FileName
        Dim Client As New WebClient()
        Client.DownloadFile(UploadUrl, UploadedPath)
        Return "True"
    Catch ex As Exception
        Return ex.Message
    End Try
End Function