用于WebClient的Windows Phone BackgroundWorker？

Question

现在WebClient问题已修复,可以在后台线程上返回,我想以这种方式开始使用它.

经过多次搜索,我想出了这个看起来工作正常的代码,这就是它的全部内容吗？

BackgroundWorker bw = new BackgroundWorker();

bw.DoWork += (s,e) =>
{
    WebClient wc = new WebClient();

    wc.DownloadStringCompleted += DownloadStringCompleted;
    wc.DownloadStringAsync(url);
};

bw.RunWorkerAsync();

在DownloadStringCompleted中,我将结果发送回UI线程.

我错过了什么重要的事情还是真的这么简单？

Answer 1

我不明白你为什么要首先WebClient在后台线程上运行,因为WebClient它已经为下载部分创建了一个线程.

不同之处在于WebClient DownloadStringCompleted在UI线程上运行它的事件.它仍然会在你的代码中做什么.

我建议你改用WebRequest班级.使用WebRequest简单的扩展方法可以大大简化类的使用,使其行为类似于WebClient.

public static class WebRequestEx
{
    public static void DownloadStringAsync(this WebRequest request, Action<string> callback)
    {
        if (request == null)
            throw new ArgumentNullException("request");

        if (callback == null)
            throw new ArgumentNullException("callback");

        request.BeginGetResponse((IAsyncResult result) =>
        {
            try
            {
                var response = request.EndGetResponse(result);
                using (var reader = new StreamReader(response.GetResponseStream()))
                {
                    callback(reader.ReadToEnd());
                }
            }
            catch (WebException e)
            {
                // Don't perform a callback, as this error is mostly due to
                // there being no internet connection available. 
                System.Diagnostics.Debug.WriteLine(e.Message);
            }
        }, request);
    }
}