将 WebClient 方法转换为 async/await

本文介绍了将 WebClient 方法转换为 async/await的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

我有一些现有代码可以移植到 Windows 8 WinRT.代码从 URL 获取数据，异步调用传递的委托:

I have some existing code which I am porting to Windows 8 WinRT. The code fetches data from URL, asynchronously invoking a passed delegate:

private void RequestData(string uri, Action<string> action)
{
  var client = new WebClient();
  client.DownloadStringCompleted += (s,e) => action(e.Result);
  client.DownloadStringAsync(new Uri(uri));
}

转换为 WinRT 需要使用 HttpClient 和异步方法.我已经阅读了一些关于 async/await 的教程，但我有点困惑.如何更改上述方法，但保留方法签名以避免更改更多代码?

Converting to WinRT requires the use of HttpClient and asynchronous methods. I've read a few tutorials on async / await, but am a bit baffled. How can I change the method above, but maintain the method signature in order to avoid changing much more of my code?

推荐答案

private async void RequestData(string uri, Action<string> action)
{
    var client = new WebClient();
    string data = await client.DownloadStringTaskAsync(uri);
    action(data);
}

请参阅:http://msdn.microsoft.com/en-us/library/hh194294.aspx

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