在Xamarin Android上实现下载监听器接口

public class MyDownloadListener : IDownloadListener
{
    public void OnDownloadStart()
    {
        // 下载开始时的操作
    }

    public void OnDownloadProgressUpdate(int progress)
    {
        // 下载进度更新时的操作
    }

    public void OnDownloadComplete()
    {
        // 下载完成时的操作
    }

    public void OnDownloadError(string errorMessage)
    {
        // 下载出错时的操作
    }
}

DownloadManager downloadManager = (DownloadManager)GetSystemService(Context.DownloadService);
DownloadManager.Request request = new DownloadManager.Request(Uri.Parse("下载链接"));
long downloadId = downloadManager.Enqueue(request);

MyDownloadListener downloadListener = new MyDownloadListener();
downloadListener.OnDownloadStart();

// 下载进度监听
new Thread(() =>
{
    bool downloading = true;
    while (downloading)
    {
        DownloadManager.Query query = new DownloadManager.Query();
        query.SetFilterById(downloadId);
        ICursor cursor = downloadManager.InvokeQuery(query);
        cursor.MoveToFirst();
        int bytesDownloaded = cursor.GetInt(cursor.GetColumnIndex(DownloadManager.ColumnBytesDownloadedSoFar));
        int bytesTotal = cursor.GetInt(cursor.GetColumnIndex(DownloadManager.ColumnTotalSizeBytes));

        if (cursor.GetInt(cursor.GetColumnIndex(DownloadManager.ColumnStatus)) == (int)DownloadStatus.Successful)
        {
            downloading = false;
            downloadListener.OnDownloadComplete();
        }
        else if (cursor.GetInt(cursor.GetColumnIndex(DownloadManager.ColumnStatus)) == (int)DownloadStatus.Failed)
        {
            downloading = false;
            downloadListener.OnDownloadError("下载出错");
        }
        else
        {
            int progress = (int)(bytesDownloaded * 100 / bytesTotal);
            downloadListener.OnDownloadProgressUpdate(progress);
        }

        cursor.Close();
    }
}).Start();