Google Drive API implementation Xamarin Android

问题:

Our application should have the functionality to save Application files to Google Drive. Of course, using the local configured account.

From Android API i tried to figure out some clue. But android API with Xamarin implementation seems very tough for me.

I have installed Google Play Services- Drive from Xamarin Components but there are no examples listed from which we can refer the flow and functionality.

回答1:

The basic steps (see the link below for full details):

• Create GoogleApiClient with the Drive API and Scope

• Try to connect (login) the GoogleApiClient

• The first time you try to connect it will fail as the user has not selected a Google Account that should be used

  • Use StartResolutionForResult to handle this condition

• When GoogleApiClient is connected

  • Request a Drive content (DriveContentsResult) to write the file contents to.

  • When the result is obtained, write data into the Drive content.

  • Set the metadata for the file

  • Create the Drive-based file with the Drive content

Note: This example assumes that you have Google Drive installed on your device/emulator and you have registered your app in Google's Developer API Console with the Google Drive API Enabled.

C# Example:

[Activity(Label = "DriveOpen", MainLauncher = true, Icon = "@mipmap/icon")]
public class MainActivity : Activity, GoogleApiClient.IConnectionCallbacks, IResultCallback, IDriveApiDriveContentsResult
{
    const string TAG = "GDriveExample";
    const int REQUEST_CODE_RESOLUTION = 3;

    GoogleApiClient _googleApiClient;

    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);

        SetContentView(Resource.Layout.Main);

        Button button = FindViewById<Button>(Resource.Id.myButton);
        button.Click += delegate
        {
            if (_googleApiClient == null)
            {
                _googleApiClient = new GoogleApiClient.Builder(this)
                  .AddApi(DriveClass.API)
                  .AddScope(DriveClass.ScopeFile)
                  .AddConnectionCallbacks(this)
                  .AddOnConnectionFailedListener(onConnectionFailed)
                  .Build();
            }
            if (!_googleApiClient.IsConnected)
                _googleApiClient.Connect();
        };
    }

    protected void onConnectionFailed(ConnectionResult result)
    {
        Log.Info(TAG, "GoogleApiClient connection failed: " + result);
        if (!result.HasResolution)
        {
            GoogleApiAvailability.Instance.GetErrorDialog(this, result.ErrorCode, 0).Show();
            return;
        }
        try
        {
            result.StartResolutionForResult(this, REQUEST_CODE_RESOLUTION);
        }
        catch (IntentSender.SendIntentException e)
        {
            Log.Error(TAG, "Exception while starting resolution activity", e);
        }
    }

    public void OnConnected(Bundle connectionHint)
    {
        Log.Info(TAG, "Client connected.");
        DriveClass.DriveApi.NewDriveContents(_googleApiClient).SetResultCallback(this);
    }

    protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
    {
        base.OnActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_CODE_RESOLUTION)
        {
            switch (resultCode)
            {
                case Result.Ok:
                    _googleApiClient.Connect();
                    break;
                case Result.Canceled:
                    Log.Error(TAG, "Unable to sign in, is app registered for Drive access in Google Dev Console?");
                    break;
                case Result.FirstUser:
                    Log.Error(TAG, "Unable to sign in: RESULT_FIRST_USER");
                    break;
                default:
                    Log.Error(TAG, "Should never be here: " + resultCode);
                    return;
            }
        }
    }

    void IResultCallback.OnResult(Java.Lang.Object result)
    {
        var contentResults = (result).JavaCast<IDriveApiDriveContentsResult>();
        if (!contentResults.Status.IsSuccess) // handle the error
            return;
        Task.Run(() =>
        {
            var writer = new OutputStreamWriter(contentResults.DriveContents.OutputStream);
            writer.Write("Stack Overflow");
            writer.Close();
            MetadataChangeSet changeSet = new MetadataChangeSet.Builder()
                   .SetTitle("New Text File")
                   .SetMimeType("text/plain")
                   .Build();
            DriveClass.DriveApi
                      .GetRootFolder(_googleApiClient)
                      .CreateFile(_googleApiClient, changeSet, contentResults.DriveContents);
        });
    }

    public void OnConnectionSuspended(int cause)
    {
        throw new NotImplementedException();
    }

    public IDriveContents DriveContents
    {
        get
        {
            throw new NotImplementedException();
        }
    }

    public Statuses Status
    {
        get
        {
            throw new NotImplementedException();
        }
    }
}

Ref: https://developers.google.com/drive/android/create-file