使用存储访问框架将文件存储在 Google 驱动器上

Question

我想使用 Android 存储访问框架存储文件。我的测试代码应该存储一个大小为 1000000 的文件 "hallo1"。但是只会创建文件大小为 0 的文件 "hallo1"。我没有收到错误消息。本地磁盘和 sd 卡上的保存工作正常 google 驱动器不工作。代码：

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

        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main);

        // Get our button from the layout resource,
        // and attach an event to it
        Button button = FindViewById<Button>(Resource.Id.myButton);

        button.Click += delegate
        {
            Intent intentCreate = new Intent(Intent.ActionCreateDocument);
            intentCreate.AddCategory(Intent.CategoryOpenable);
            intentCreate.SetType("audio/*");
            intentCreate.PutExtra(Intent.ExtraTitle, "hallo" + count);
            StartActivityForResult(intentCreate, 1);

            count++;
        };
    }

    protected override  void OnActivityResult(int requestCode, Result resultCode, Intent data)
    {
        var stream = this.ContentResolver.OpenOutputStream(data.Data, "w");
        var b = new byte[1000000];
        stream.Write(b, 0, b.Length);
        stream.Flush();
        stream.Close();

        base.OnActivityResult(requestCode, resultCode, data);
    }

Filepicker from the android storage access framework

Enter the filename (default "hallo1" from the code)

data.Data 给出内部 Android.Net.Uri 返回。

有人知道问题出在哪里吗？

Answer 1

Store file with the storage access framework on Google Drive

请参考：

其他有用的links:

Xamarin 表单上传到 google 驱动器

更新：

With internal storage it works and in my opinion it should also work with google drive.

不使用Google驱动器API无法直接实现此功能，您应该先创建文件，然后将文件上传到Google 像这样开车：

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);
    });
}

更详细的信息参考上面的link我post：.

此外，您可以使用 Xamarin.Google.Drive.Api.Android nuget package to implement this feature easily, simple demo from the document:

CloudRail.AppKey = "{Your_License_Key}";
// Google Drive:
GoogleDrive drive = new GoogleDrive(this, "[clientIdentifier]", "", "[redirectUri]", "[state]");
drive.UseAdvancedAuthentication();
ICloudStorage cs = drive;

new System.Threading.Thread(new System.Threading.ThreadStart(() =>
{
    try
    {
        IList<CloudMetaData> filesFolders = cs.GetChildren("/");
        //IList<CloudMetaData> filesFolders = cs.GetChildrenPage("/", 1, 4);  // Path, Offet, Limit
        //cs.Upload(/image_2.jpg,stream,1024,true);   // Path and Filename, Stream (data), Size, overwrite (true/false)
    }
    catch (Exception e)
    {
        System.Console.WriteLine(e.Message);
    }
 })).Start();

更新 2：

To get the filename I found but not the folder name.

您需要先从 URI 中获取 Cursor，然后您可以检查列名等。

对于Google驱动器，有一个列名_display_name。这将为您提供文件名。

protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
    var uri = data.Data;
    ICursor cursor = this.ContentResolver.Query(uri, null, null, null, null);
    cursor.MoveToFirst();

    var filenameIndex = cursor.GetColumnIndex("_display_name");
    var filename = cursor.GetString(filenameIndex);
    System.Diagnostics.Debug.WriteLine("filename == " + filename);
}

Answer 2

我找到了解决方案：

        protected override  void OnActivityResult(int requestCode, Result resultCode, Intent data)
    {

        // this works fine:
        using (System.IO.Stream stream = this.ContentResolver.OpenOutputStream(data.Data, "w"))
        {
            using (var javaStream = new Java.IO.BufferedOutputStream(stream))
            {
                var b = new byte[1000000];
                javaStream.Write(b, 0, b.Length);
                javaStream.Flush();
                javaStream.Close();
            }
        }

        // the direct writing on the System.IO.Stream failed:
        //using (System.IO.Stream stream = this.ContentResolver.OpenOutputStream(data.Data, "w"))
        //{
        //    var b = new byte[1000000];
        //    stream.Write(b, 0, b.Length);
        //    stream.Flush();
        //    stream.Close();
        //}

        base.OnActivityResult(requestCode, resultCode, data);
    }

有人知道为什么这行得通，而使用 System.IO.Stream 直接写入失败了吗？

使用存储访问框架将文件存储在 Google 驱动器上

Store file with the storage access framework on Google Drive

c#

android

xamarin.android

storage-access-framework

更新：

更新 2：