如何使用在此范围内WebClient.DownloadDataAsync（）方法？ [英] How to use the WebClient.DownloadDataAsync() method in this context?

问题描述

我的计划是有一个用户写下电影标题在我的计划，我的程序将异步拉此时，相应的信息，以便用户界面不会冻结。

My plan is to have a user write down a movie title in my program and my program will pull the appropiate information asynchronously so the UI doesn't freeze up.

这里的code：

public class IMDB
    {
        WebClient WebClientX = new WebClient();
        byte[] Buffer = null;


        public string[] SearchForMovie(string SearchParameter)
        {
            //Format the search parameter so it forms a valid IMDB *SEARCH* url.
            //From within the search website we're going to pull the actual movie
            //link.
            string sitesearchURL = FindURL(SearchParameter);

            //Have a method download asynchronously the ENTIRE source code of the
            //IMDB *search* website.
            Buffer = WebClientX.DownloadDataAsync(sitesearchURL);


            //Pass the IMDB source code to method findInformation().

            //string [] lol = findInformation();

            //????

            //Profit.

            string[] lol = null;
            return lol;
        }

我的实际问题就出在WebClientX.DownloadDataAsync（）方法。我不能使用字符串URL它。我怎么可以使用内置的功能来下载网站的字节数（以备后用，我将它转换为字符串，我知道如何做到这一点），并且不结冰了我的GUI？

My actual problem lies in the WebClientX.DownloadDataAsync() method. I can't use a string URL for it. How can I use that built in function to download the bytes of the site (for later use I will convert this to string, I know how to do this) and without freezing up my GUI?

也许DownloadDataAsync的一个明确的例子，所以我可以学习如何使用它？

Perhaps a clear cut example of the DownloadDataAsync so I can learn how to use it?

太感谢，你总是这样一个伟大的资源。

Thanks SO, you're always such a great resource.

推荐答案

您需要处理 DownloadDataCompleted 事件：

static void Main()
{
    string url = "http://google.com";
    WebClient client = new WebClient();
    client.DownloadDataCompleted += DownloadDataCompleted;
    client.DownloadDataAsync(new Uri(url));
    Console.ReadLine();
}

static void DownloadDataCompleted(object sender,
    DownloadDataCompletedEventArgs e)
{
    byte[] raw = e.Result;
    Console.WriteLine(raw.Length + " bytes received");
}

该ARGS包含有关错误情况等信息的其他位 - 检查那些过于

The args contains other bits of information relating to error conditions etc - check those too.

另外请注意，你会进入 DownloadDataCompleted 在不同的线程;如果你是在UI（WinForm的，WPF等），你将需​​要更新UI之前到UI线程。从的WinForms，使用 this.Invoke 。对于WPF，看调度。

Also note that you'll be coming into DownloadDataCompleted on a different thread; if you are in a UI (winform, wpf, etc) you'll need to get to the UI thread before updating the UI. From winforms, use this.Invoke. For WPF, look at the Dispatcher.

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