c# - 在 Monodroid/C# 中将 AsyncTask 转换为任务

Question

我想知道如何使用 .NET 的异步库实现这个 Android AsyncTask:

public class LoadRecordTask : AsyncTask
{
    private Activity1 _context;
    private int _recordId;

    public LoadRecordTask( Activity1 outerActivity, int recordId )
    {
        _context = outerActivity;
        _recordId = recordId;
    }

    protected override void OnPreExecute()
    {
        base.OnPreExecute();

        _progressDialog = Android.App.ProgressDialog.Show( _context , "", "Loading record {0}", _recordId );
    }

    protected override Java.Lang.Object DoInBackground(params Java.Lang.Object[] @params)
    {
        _bSuccess = LoadRecord( _recordId );

        if( !_bSuccess )
        {
            return false;
        }

        return true;
    }

    protected override void OnPostExecute(Java.Lang.Object result)
    {
        base.OnPostExecute(result);

        if( !_bSuccess )
        {           
            _progressDialog.SetMessage( "Error loading recording." );
        }

        _progressDialog.Dismiss();
    }
}

Answer 1

AsyncTask您正在使用的可以翻译为:

_progressDialog = ProgressDialog.Show( _context , "", "Loading record {0}", _recordId );

if (await LoadRecord(_recordId))
    _progressDialog.Dismiss();
else
    _progressDialog.SetMessage( "Error loading recording." );

哪里LoadRecord可能会返回Task<bool>以及 Task 内部运行的内部结构。否则你可以只包装 LoadRecord您当前在 Task 中使用的方法使其异步运行。

private Task<bool> LoadRecord(int recordId)
{
    return Task<bool>.Run(() => 
    {
        //Do stuff here to fetch records
        return true;
    });
}

您调用await 的方法需要标记为异步。即:

private async void MyAwesomeAsyncMethod() {}