避免在Xamarinn Forms Android上播放音频时使用过时的Forms.Context

Question

如何使用Xamarin Forms在Android上播放音频？我有以下服务，但是可以使用，但是Forms.Context不再支持，消息为“上下文从版本2.5开始已过时。请改用本地上下文。”。

[assembly: Dependency(typeof(AudioService))]
namespace SensaLabScan.Droid.Services
{
    public class AudioService : IAudioService
    {
        private readonly MediaPlayer _mediaPlayer = new MediaPlayer();

        public void PlayBeep()
        {
            _mediaPlayer.Reset();

            // Forms.Context references the Activity which calls Forms.Init, i.e. MainActivity.
            using (var beepFile = Forms.Context.Assets.OpenFd("beep.mp3"))
            {
                _mediaPlayer.SetDataSource(beepFile);
                _mediaPlayer.Prepare();
                _mediaPlayer.Start();
            }
        }
    }
}

在这种情况下，替代已弃用的Forms.Context有什么选择？我已经尝试过

1. [Android.App.Application.Context.Assets.OpenFd("beep.pm3");，但这会引发文件未找到异常
2. 使用MainActivity作为上下文，并从中使用Assets，但仍然是找不到文件错误。

我要阅读的mp3文件位于Assets文件夹中，并标记为AndroidAsset。

Answer 1

这是使用DependenceService播放音频的代码。

 [assembly: Dependency(typeof(MyDependenceService))]
 namespace MediaPlayDemo.Droid
 {
public class MyDependenceService : IPlayMedia
{
    public void playMusic()
    {
        //throw new NotImplementedException();


        var bytes = default(byte[]);
        using (StreamReader reader = new StreamReader(Android.App.Application.Context.Assets.Open("Test.mp3")))
        {
            using (var memstream = new MemoryStream())
            {
                reader.BaseStream.CopyTo(memstream);
                bytes = memstream.ToArray();
            }
        }
        Play(bytes);
    }


        //  Stop();

        MediaPlayer currentPlayer;
        public void Play(byte[] AudioFile)
        {
            Stop();
            currentPlayer = new MediaPlayer();
            currentPlayer.Prepared += (sender, e) =>
            {
                currentPlayer.Start();
            };
            currentPlayer.SetDataSource(new StreamMediaDataSource(new System.IO.MemoryStream(AudioFile)));
            currentPlayer.Prepare();
        }

        void Stop()
        {
            if (currentPlayer == null)
                return;

            currentPlayer.Stop();
            currentPlayer.Dispose();
            currentPlayer = null;
        }




}

public class StreamMediaDataSource : MediaDataSource
{
    System.IO.Stream data;

    public StreamMediaDataSource(System.IO.Stream Data)
    {
        data = Data;
    }

    public override long Size
    {

        get
        {
            return data.Length;
        }
    }

    public override int ReadAt(long position, byte[] buffer, int offset, int size)
    {
        data.Seek(position, System.IO.SeekOrigin.Begin);
        return data.Read(buffer, offset, size);
    }

    public override void Close()
    {
        if (data != null)
        {
            data.Dispose();
            data = null;
        }
    }

    protected override void Dispose(bool disposing)
    {
        base.Dispose(disposing);

        if (data != null)
        {
            data.Dispose();
            data = null;
        }
    }
}
}