如何实现异步..NET中外部使用的已完成事件
本文关键字：外部 事件 已完成 NET 何实现 实现 异步 | 更新日期: 2023-09-27 18:24:07
我有一个简单的项目来获取HTML元素的内部数据。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 = "<html>";
IHTMLElement head = (IHTMLElement)((IHTMLElementCollection)doc.all.tags("head")).item(null, 0);
result += "<head>" + head.innerHTML + "</head>";
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 += "<body>" + div.IHTMLElement_innerHTML + "</body></html>";
break;
}
}
else
{
string className = div.className;
if (className == Element)
{
result += "<body>" + div.IHTMLElement_innerHTML + "</body></html>";
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异步获取此变量。
也许我需要一些GetResult（）；方法
我该怎么做？
谢谢！
您可以将事件处理程序作为参数传递，然后在类库中的应用程序no中处理结果o只需传递回调并在下载完成后调用即可。
我是新来的，所以我希望我能理解你想要什么。
通过evnthandler
public void GetPageElementInnerHTML（字符串url、字符串元素、布尔findById、WebBrowserDocumentCompletedEventHandler downloadComplete）
使用代理人：
公共类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 = "<html>";
IHTMLElement head = (IHTMLElement)((IHTMLElementCollection)doc.all.tags("head")).item(null, 0);
result += "<head>" + head.innerHTML + "</head>";
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 += "<body>" + div.IHTMLElement_innerHTML + "</body></html>";
break;
}
}
else
{
string className = div.className;
if (className == Element)
{
result += "<body>" + div.IHTMLElement_innerHTML + "</body></html>";
break;
}
}
}
}
}
doc.close();
_downloadedComplete.Invoke(result);
}
}
在APP 中
GetPageElementInnerHTML（URL，元素，true/false，CompletedCallback）；
private void CompletedCallback（字符串结果）{//您的代码
}
以下是工作代码：
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 = "<html>";
IHTMLElement head = (IHTMLElement)((IHTMLElementCollection)doc.all.tags("head")).item(null, 0);
result += "<head>" + head.innerHTML + "</head>";
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 += "<body>" + div.IHTMLElement_innerHTML + "</body></html>";
break;
}
}
else
{
string className = div.className;
if (className == Element)
{
result += "<body>" + div.IHTMLElement_innerHTML + "</body></html>";
break;
}
}
}
}
}
doc.close();
this.Add(result);
}
}
}
这是我们称之为的代码
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];
}