青岛网站开发学校,wordpress页面样板,滁州网站开发,嘉兴网站网站建设在用WebBrowser编程实现网页操作自动化时#xff0c;常要分析网页Html#xff0c;例如网页在加载数据时#xff0c;常会显示“系统处理中#xff0c;请稍候..”#xff0c;我们需要在数据加载完成后才能继续下一步操作#xff0c;如何抓取这个信息的网页html元素变化常要分析网页Html例如网页在加载数据时常会显示“系统处理中请稍候..”我们需要在数据加载完成后才能继续下一步操作如何抓取这个信息的网页html元素变化从而判断数据加载完毕呢用IE开发者工具是不可能抓取到的太快了。(当然设置足够长的延时也是可以实现的只是不够科学及稳妥毕竟有时因为网络原因数据加载时间可能超过原来设定时间其次设置延时过长也导致程序不够友好
实现的办法
1、先用“系统处理中”查找泛查找并在找到html中再细找缩小html元素范围。
bb FindHtmlElement(系统处理中, ExtendedWebBrowser1.Document, , InnerText, false)
2、添加一个Timer控件设定100毫秒。根据 1中找到的元素进行不断抓取并将抓到的结果输出到文本。
3、将2中输出导入Excel进行筛选并从中找到重复次数少的行便是数据加载、加载完成之间的变化。
Private Sub TimerProgress_Tick(sender As Object, e As EventArgs) Handles TimerProgress.TickIf Gethtmel ThenDim bb As HtmlElementbb FindHtmlElement(all_jzts, ExtendedWebBrowser1.Document, div, id, True)If Not bb Is Nothing ThenWriteRunLog(Style bb.Style)WriteRunLog(bb.OuterHtml)ElseWriteRunLog(all_jzts没找到)End Ifbb FindHtmlElement(jzts, ExtendedWebBrowser1.Document, div, id, True)If Not bb Is Nothing ThenWriteRunLog(Style bb.Style)WriteRunLog(bb.OuterHtml)ElseWriteRunLog(jzts没找到)End IfGethtmel FalseEnd If系统处理中请稍候...Application.DoEvents()End Sub Function FindHtmlElement(ByVal FindText As String, ByVal doc As HtmlDocument, ByVal cTagName As String, ByVal cGetAttribute As String, Optional ByVal StrictMatching As Boolean False) As HtmlElementcTagName检索具有指定 html 标记的元素标记需要输入完整的缺省时查找所有。例如input classbutton typesubmit value提交 stylecursor:hand不能只输入i需要输入inputcGetAttribute 比较的属性类型取值为Id、InnerText、Name、title、classname、value、Id、InnerText可以通过GetAttribute获取也可以通过HtmlElement.Id、HtmlElement.InnerText获取所以代码简化为用GetAttribute获取。docWebBrowserExt1.DocumentGetAttribute(classname) 例如显示classcommonTable的值commonTableStrictMatchingTrue严格匹配FindTextWriteRunLog(FindHtmlElement开始 FindText)TryDim i, k As IntegerFindHtmlElement NothingFindHtmlElementOfDocument docIf doc Is Nothing Then 2023.11.15在递归调用中因为有些iFrames还未真正加载从而导致传入的doc doc.Window.Frames.Item(k).Document 为 Nothing 从而引发异常未将对象引用设置到对象的实例。Exit FunctionEnd IfIf LCase(cGetAttribute) innertext Then InnerText必须严格匹配否则找到的结果是错误的。’StrictMatching TrueEnd IfIf cTagName ThenDim EE As HtmlElementCollection doc.GetElementsByTagName(cTagName)For i 0 To EE.Count - 1If InStr(EE.Item(i).GetAttribute(cGetAttribute), FindText) 0 _And (Not StrictMatching Or InStr(FindText, EE.Item(i).GetAttribute(cGetAttribute)) 0) ThenFindHtmlElement EE.Item(i)WriteRunLog(Loop1)WriteRunLog(FindHtmlElement结束0)Exit Function 找到就退出End IfNextElseFor i 0 To doc.All.Count - 1If InStr(doc.All.Item(i).GetAttribute(cGetAttribute), FindText) 0 _And (Not StrictMatching Or InStr(FindText, doc.All.Item(i).GetAttribute(cGetAttribute)) 0) And (cTagName Or LCase(cTagName) LCase(doc.All.Item(i).TagName)) ThenFindHtmlElement doc.All.Item(i)WriteRunLog(Loop1)WriteRunLog(FindHtmlElement结束0)Exit Function 找到就退出End IfNextEnd If上面没找到进行递归调用递归会查找所有嵌套的Frame。For k 0 To doc.Window.Frames.Count - 1If k 0 Then WriteRunLog(递归调用 doc.Window.Frames.Count doc.Window.Frames.Count.ToString) For TestEnd If2018.3.14 直接 递归调用WriteRunLog(递归调用 Str(k)) WriteRunLog(doc.Window.Frames.Item(k).Name doc.Window.Frames.Item(k).Name)FindHtmlElementOfDocument doc.Window.Frames.Item(k).DocumentFindHtmlElement FindHtmlElement(FindText, doc.Window.Frames.Item(k).Document, cTagName, cGetAttribute, StrictMatching)If Not FindHtmlElement Is Nothing Then 找到就退出循环WriteRunLog(FindHtmlElement结束1)Exit FunctionEnd IfNextCatch ex As ExceptionFindHtmlElement NothingWriteRunLog(FindHtmlElement发生异常 ex.Message)End TryEnd FunctionSub WriteRunLog(ByVal MyMsg As String)Using w As StreamWriter File.AppendText(RunLog.txt)Dim w As StreamWriterIf File.Exists(RunLog.txt) ThenIf My.Computer.FileSystem.GetFileInfo(RunLog.txt).Length 10485760 Then 2017.5.4 文件大于10M清0w File.CreateText(RunLog.txt)w.Write(文件大于10M置0从头开始)w.Write(Chr(9))Elsew File.AppendText(RunLog.txt)End IfElsew File.CreateText(RunLog.txt)End Ifw.Write(Now)w.Write(Chr(9)) 插入Tab键w.WriteLine(MyMsg)w.Flush()w.Close()End UsingEnd Sub
