C# OpenReadTaskAsync工作不正常？

所以我试着让后台代理每30秒下载一张图片。调用该函数时，它将调用此函数“DownloadImageFromServer”。使用断点，我发现它命中了OpenReadTaskAsync函数调用，但似乎跳过了剩余的代码（那里的断点从未命中）。此外，它还没有下载图像。你知道是什么引起的吗

      private async void DownloadImagefromServer(string imgUrl)
    {
        Debug.WriteLine("Attempting to Get Image from Server...");
        WebClient client = new WebClient();



    var result = await client.OpenReadTaskAsync(new Uri(imgUrl, UriKind.Absolute));
    //============================================================
    //THE BELOW CODE IS NEVER HIT WHEN PUT WITH BREAKPOINTS
    /=============================================================
            BitmapImage bitmap = new BitmapImage();
            bitmap.SetSource(result);

            // Create a filename for JPEG file in isolated storage.
            String tempJPEG = "DownloadedWalleper.jpg";

            // Create virtual store and file stream. Check for duplicate tempJPEG files.
            using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
            {
                if (myIsolatedStorage.FileExists(tempJPEG))
                {
                    myIsolatedStorage.DeleteFile(tempJPEG);
                }

                IsolatedStorageFileStream fileStream = myIsolatedStorage.CreateFile(tempJPEG);

                StreamResourceInfo sri = null;
                Uri uri = new Uri(tempJPEG, UriKind.Relative);
                sri = Application.GetResourceStream(uri);


                WriteableBitmap wb = new WriteableBitmap(bitmap);

                // Encode WriteableBitmap object to a JPEG stream.
                Extensions.SaveJpeg(wb, fileStream, wb.PixelWidth, wb.PixelHeight, 0, 85);


                fileStream.Close();
            }
            LockScreenChange("DownloadedWalleper.jpg", false);


    }

---

如果您使用的是.NET 4.5，则只需创建一个新的

webclient

，并使用async下载该文件即可

例如：

private void btnDownload_Click(object sender, EventArgs e)
{
  WebClient webClient = new WebClient();
  webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed);
  webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(ProgressChanged);
  webClient.DownloadFileAsync(new Uri("http://example.com/myfile.txt"), @"c:\myfile.txt");
}

---

不要使用

async void

。我应该使用什么呢？

async Task

是您应该使用的

async void

仅用于“触发并忘记”异步方法，如事件处理程序。您不能使用

await

异步void方法。当我将其更改为

async task

并让其返回任务时，VS会给我错误

错误“await”运算符只能在异步方法中使用。考虑将此方法标记为“AsiNC”修饰符并将其返回类型改为“任务”< /代码>。这与我的
OpenReadTaskAsync
方法位于同一行