如何实现异步。 在.NET中完成外部使用事件？

我有这个简单的项目来获取HTML元素内部数据。 这是一个DLL项目。

public class WebGrabber { public string URL { set; get; } public string Element { set; get; } public bool FindByID { set; get; } private WebBrowser b { set; get; } private mshtml.IHTMLDocument2 doc { set; get; } public void GetPageElementInnerHTML(string url, string element, bool findById) { URL = url; Element = element; FindByID = findById; b = new WebBrowser(); b.Navigate(url); b.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(b_DocumentCompleted); } void b_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) { doc = (IHTMLDocument2)b.Document.DomDocument; string result = ""; IHTMLElement head = (IHTMLElement)((IHTMLElementCollection)doc.all.tags("head")).item(null, 0); result += "" + head.innerHTML + ""; if (null != doc) { foreach (IHTMLElement element in doc.all) { if (element is mshtml.IHTMLDivElement) { dynamic div = element as HTMLDivElement; if (FindByID) { string id = div.id; if (id == Element) { result += "" + div.IHTMLElement_innerHTML + ""; break; } } else { string className = div.className; if (className == Element) { result += "" + div.IHTMLElement_innerHTML + ""; break; } } } } } doc.close(); } } 

我需要的是实现对字符串结果变量的访问 。

因此，可以从其他项目中异步获取此变量 。

也许我需要一些GetResult（）; 方法？….

我怎么能这样做？

谢谢！

Answer 1

您可以将eventhandler作为参数传递，然后在类库中的app no中使用结果o只需传递回调并在下载完成后调用。

我是新来的，所以我希望我明白你想要的。

通过evnthandler

public void GetPageElementInnerHTML（string url，string element，bool findById，WebBrowserDocumentCompletedEventHandler downloadComplete）

使用代表：

公共课WebGrabber {

  public string URL { set; get; } public string Element { set; get; } public bool FindByID { set; get; } private WebBrowser b { set; get; } private mshtml.IHTMLDocument2 doc { set; get; } public delegate void DownloadCompletedDelegate(string result); private DownloadCompletedDelegate _downloadedComplete; public void GetPageElementInnerHTML(string url, string element, bool findById, DownloadCompletedDelegate downloadComplete) { _downloadedComplete = downloadComplete; URL = url; Element = element; FindByID = findById; b = new WebBrowser(); b.Navigate(url); b.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(b_DocumentCompleted); } void b_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) { doc = (IHTMLDocument2)b.Document.DomDocument; string result = ""; IHTMLElement head = (IHTMLElement)((IHTMLElementCollection)doc.all.tags("head")).item(null, 0); result += "" + head.innerHTML + ""; if (null != doc) { foreach (IHTMLElement element in doc.all) { if (element is mshtml.IHTMLDivElement) { dynamic div = element as HTMLDivElement; if (FindByID) { string id = div.id; if (id == Element) { result += "" + div.IHTMLElement_innerHTML + ""; break; } } else { string className = div.className; if (className == Element) { result += "" + div.IHTMLElement_innerHTML + ""; break; } } } } } doc.close(); _downloadedComplete.Invoke(result); } } 

在APP中

GetPageElementInnerHTML（URL，element，true / false，CompletedCallback）;

private void CompletedCallback（字符串结果）{//您的代码

}

Answer 2

这是工作代码：

 using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Windows.Forms; using mshtml; using System.Collections; namespace MyCompany.WebpageGrabber { // A delegate type for hooking up change notifications. public delegate void ChangedEventHandler(object sender, EventArgs e); public class WebGrabber : ArrayList { // An event that clients can use to be notified whenever the // elements of the list change. public event ChangedEventHandler Changed; // Invoke the Changed event; called whenever list changes protected virtual void OnChanged(EventArgs e) { if (Changed != null) Changed(this, e); } // Override some of the methods that can change the list; // invoke event after each public override int Add(object value) { int i = base.Add(value); OnChanged(EventArgs.Empty); return i; } public override void Clear() { base.Clear(); OnChanged(EventArgs.Empty); } public override object this[int index] { set { base[index] = value; OnChanged(EventArgs.Empty); } } public string URL { set; get; } public string Element { set; get; } public bool FindByID { set; get; } private WebBrowser b { set; get; } private mshtml.IHTMLDocument2 doc { set; get; } public void GetPageElementInnerHTML(string url, string element, bool findById) { URL = url; Element = element; FindByID = findById; b = new WebBrowser(); b.Navigate(url); b.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(b_DocumentCompleted); } void b_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e) { doc = (IHTMLDocument2)b.Document.DomDocument; string result = ""; IHTMLElement head = (IHTMLElement)((IHTMLElementCollection)doc.all.tags("head")).item(null, 0); result += "" + head.innerHTML + ""; if (null != doc) { foreach (IHTMLElement element in doc.all) { if (element is mshtml.IHTMLDivElement) { dynamic div = element as HTMLDivElement; if (FindByID) { string id = div.id; if (id == Element) { result += "" + div.IHTMLElement_innerHTML + ""; break; } } else { string className = div.className; if (className == Element) { result += "" + div.IHTMLElement_innerHTML + ""; break; } } } } } doc.close(); this.Add(result); } } } 

这是我们称之为代码的代码：

 private void Window_Loaded(object sender, RoutedEventArgs e) { WebGrabber g = new WebGrabber(); g.GetPageElementInnerHTML("http://www.google.com/web/guest/home", "portlet-borderless-container", false); g.Changed += new ChangedEventHandler(g_Changed); } void g_Changed(object sender, EventArgs e) { var html = ((WebGrabber)sender)[0]; }