Xamarin Android-在资产文件夹中设置mp3铃声

Question

我使用Xamarin Forms并使用依赖服务从资产文件夹中的mp3位置设置铃声。这是我的代码：

AssetManager assets = Forms.Context.Assets;
    fileName = "Artist.mp3";
    System.IO.Stream inputStream;
    System.IO.Stream outputStream;
    try
    {
        inputStream = assets.Open("Sounds/" + fileName);
      **_  outputStream = Forms.Context.OpenFileOutput(fileName, FileCreationMode.Private); _**
        byte[] buffer = new byte[65536 * 2];
        int read;
        while ((read = inputStream.Read(buffer, 0, (int)inputStream.Length)) != -1)
        {
            outputStream.Write(buffer, 0, read);
        }
        inputStream.Close();
        inputStream = null;
        outputStream.Flush();
        outputStream.Close();
        outputStream = null;
        Java.IO.File newSoundFile = new Java.IO.File(basepath + "/Sounds/" + fileName);
        if (newSoundFile.Exists())
        {
            ContentValues values = new ContentValues();
            values.Put(MediaStore.MediaColumns.Data, newSoundFile.AbsolutePath);
            values.Put(MediaStore.MediaColumns.Title, "Test Ringtone");
            values.Put(MediaStore.MediaColumns.MimeType, "audio/*");
            values.Put(MediaStore.MediaColumns.Size, newSoundFile.Length());
            values.Put(MediaStore.Audio.Media.InterfaceConsts.Artist, "Artist MP3");
            values.Put(MediaStore.Audio.Media.InterfaceConsts.Duration, 2300);
            values.Put(MediaStore.Audio.Media.InterfaceConsts.IsRingtone, true);
            values.Put(MediaStore.Audio.Media.InterfaceConsts.IsNotification, false);
            values.Put(MediaStore.Audio.Media.InterfaceConsts.IsAlarm, false);
            values.Put(MediaStore.Audio.Media.InterfaceConsts.IsMusic, false);
            Android.Net.Uri uri = MediaStore.Audio.Media.GetContentUriForPath(newSoundFile.AbsolutePath);
            Forms.Context.ContentResolver.Delete(uri, MediaStore.MediaColumns.Data + "="" + newSoundFile.AbsolutePath + """, null);
            Android.Net.Uri newUri = Forms.Context.ContentResolver.Insert(uri, values);
            try
            {
                RingtoneManager.SetActualDefaultRingtoneUri(Forms.Context, RingtoneType.Ringtone, newUri);
            }
            catch (Exception e)
            {
            }
        }
    }
    catch (Exception e)
    {
    }

我在outputStream=Forms.Context.OpenFileOutput（fileName，FileCreationMode.Private）行中得到以下异常

System.NotSupportedException：不支持指定的方法。在/Users/builder/data/lanes/3053/a94a03b5/source/monodroid/src/Monol.Android/src/Runtime/InputStreamInvoker.cs:55 中的Android.Runtime.InputStreamInvoker.get_Length（）[0x0000]

您正在手动实现Stream.CopyTo。使用它即可。

using (var inputStream = assets.Open("Sounds/" + fileName))
using (var outputStream = Forms.Context.OpenFileOutput(fileName, FileCreationMode.Private))
{
    inputStream.CopyTo(outputStream);
}