Question

我一直在寻找相当长的时间，但我似乎无法为我的代码找到解决方案。当它进入if (e.Error != null)条件时，我怎么能处理异常，换句话说，当异步调用出现错误时？

private static StorageClient client = new StorageClient();

private static void TransferCompletion<T>(TaskCompletionSource<T> tcs, System.ComponentModel.AsyncCompletedEventArgs e, Func<T> getResult)
    {
        if (e.Error != null)
        {
            MessageBox.Show("1");
            tcs.TrySetException(e.Error);               
        }
        else if (e.Cancelled)
        {
            MessageBox.Show("2");
            tcs.TrySetCanceled();
        }
        else
        {
            MessageBox.Show("3");
            tcs.TrySetResult(getResult());
        }
    }

    public static Task<getAllProvidersCompletedEventArgs> GetAllProvidersTask(this StorageClient client)
    {
        var tcs = new TaskCompletionSource<getAllProvidersCompletedEventArgs>();
        client.getAllProvidersCompleted += (s, e) => TransferCompletion(tcs, e, () => e);
        client.getAllProvidersAsync();
        return tcs.Task;
    }

这就是我在主打中所说的：

var client = new StorageClient();
var providers_data = await client.GetAllProvidersTask();

我按照这个例子编写了我的代码：How can I use async/await to call a webservice?

Answer 1

在包含try表达式的语句周围添加await块：

try
{
  var client = new StorageClient();
  var providers_data = await client.GetAllProvidersTask();
}
catch (Exception ex)
{
  ...
  throw;
}

C＃WP8处理异步调用异常

1 个答案: