最近一个小项目,开发一个插件,需要对一个第三方系统的网页内容进行操作.操作的内容还比较复杂.自然选择用BHO做.
做到一半卡住了,原因在于这个网站有一个showmodal的模式窗口,需要对这个弹出的模式窗口也进行控制.
但是找遍了DOM和IE的各个接口也没找到能控制或捕获弹出窗口内容的东西.
虽然可以重写弹出窗口的代码,改用window.open方式弹出,再进行捕获,但因为那网站的弹出窗口还带了复杂的参数,不方便转换,所以保持不能改他的代码.
既然从IE方向无法下手,就只能改变方向,从Windows窗口方向下手.因为弹出窗口也是窗口,可以进行捕获弹出窗口句柄,然后遍历出Webbrowser控制句柄,再转换成Document对象.得到Document对象就可以对网页进行随意控制了.
关键代码如下:
'BHO类中下勾子
hWndRetProcHook = SetWindowsHookEx(HookType.WH_CALLWNDPROCRET, AddressOf modCallback.CallWndRetProc, 0, App.ThreadID)
'再手工弹出模式窗口.
htmlDOM.parentWindow.execScript "btnReNewCard()", "JScript"
此时标准模块中的CallWndRetProc开始工作了,代码如下(省略部门代码的声名):
Public Function CallWndRetProc(ByVal code As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
On Error GoTo ErrorLine
Dim hwnd As Long
Dim script As MSHTML.HTMLScriptElement
If code <> 0 Then
CallWndRetProc = CallNextHookEx(hWndRetProcHook, code, wParam, lParam)
Exit Function
End If
CopyMemory hCWPRETSTRUCT, ByVal lParam, LenB(hCWPRETSTRUCT)
If hCWPRETSTRUCT.Message = WM_PARENTNOTIFY Then Debug.Print hCWPRETSTRUCT.wParam, hCWPRETSTRUCT.hwnd If hCWPRETSTRUCT.wParam = WM_CREATE Then EnumChildWindows hCWPRETSTRUCT.hwnd, AddressOf EnumChildProc, hwnd
'注意到以下代码都是注释的,实际项目中已经删除了,这里留下只为演示,后面解释为什么要注释掉.' If hwnd = 0 Then' MsgBox "获取浏览器信息失败,请重试.", vbExclamation' Exit Function' End If
' Set NewhtmlDOM = IEDOMFromhWnd(hwnd)' If Not (NewhtmlDOM Is Nothing) Then' Set script = NewhtmlDOM.createElement("Script")' script.Text = "var getCardScript = function(){" & vbCrLf & _' " getScrapCardScript();" & vbCrLf & _' " }" & vbCrLf & _' " var refreshCard =function(){" & vbCrLf & _' " if(hasErrMsg()) {" & vbCrLf & _' " return;" & vbCrLf & _' " }" & vbCrLf & _' " writeFlag=true;" & vbCrLf & _' " var noticeInfo={};" & vbCrLf & _' " // Comments 字段在下发时设置具体的错误信息" & vbCrLf & _' " if(writeFlag==true){" & vbCrLf & _' " noticeInfo.Result=""1"";" & vbCrLf & _' " //noticeInfo.Comments=""成功"";" & vbCrLf & _' " }" & vbCrLf & _' " else{" & vbCrLf & _' " noticeInfo.Result=""2"";" & vbCrLf & _' " noticeInfo.ErrorCode=writeFlag;" & vbCrLf & _' " //noticeInfo.Comments=""失败"";" & vbCrLf & _' " }" & vbCrLf & _' " addBizState(""noticeInfo"",noticeInfo);" & vbCrLf & _' " scrapCardReturnNotice();" & vbCrLf & _' " }"' script.language = "Javascript"' 'Debug.Print InStr(0, "authKey", htmlDOM.scripts(5).Text, vbTextCompare)' While NewhtmlDOM.ReadyState <> "complete"' DoEvents' Wend' NewhtmlDOM.body.appendChild script' Else' MsgBox "获取浏览对象失败.", vbExclamation' End If 'UnhookWindowsHookEx hWndRetProcHook End If End If CallWndRetProc = CallNextHookEx(hWndRetProcHook, code, wParam, lParam) Exit FunctionErrorLine: MsgBox "发生异常." & Err.Description, vbCritical CallWndRetProc = CallNextHookEx(hWndRetProcHook, code, wParam, lParam)End Function因为IE的ShowModal方法弹出窗口会产生WM_PARENTNOTIFY消息和WM_Create消息,所以只对这两个消息进行监控.监控到弹出窗口后,就用EnumChildWindows遍历弹出窗口的所有子窗口,以得到Webbrowser的句柄.在上面的代码中看到,EnumChildWindows后有大片的注释代码.
我的原意是想用EnumChildWindows的最后一个参数来输出EnumWindowProc子程查找到的Webbrowser句柄,我将这个参数声名为byref.这段代码在我Win7下运行正常,并且输出了Webbrowser句柄.但是当项目完成后移到WindowsXP测试时,居然无法输出遍历得到的句柄了.MSDN中没说这个参数只能输入不能输出啊!而且我在Win7下运行相当正确啊,百思不得其解.
一开始以为是user32.dll版本问题,将WIN7的这个文件复制到XP的DLL和IE根目录下,问题依旧存在,所以无奈,只能取消用EnumChildWindows返回句柄的方式,改在EnumWindowProc子程中处理,于是注释上上面那段代码.
另外有注意到,上面代码中,取消Hook的代码是单独一行注释的,我的本意是,在获得完Webbrowser控件后就unhook,这句代码在WIN7运行的也是相当好,但是转到XP就不行了,所以也注释了这行代码,改到后面unhook.
下面是EnumWindowProc子程.
Function EnumChildProc(ByVal hwnd As Long, ByRef lParam As Long) As Long
Dim script As MSHTML.HTMLScriptElement
If IsIEServerWindow(hwnd) Then
lParam = hwnd
'找到句柄后,将句柄转换成Document对象. Set NewhtmlDOM = IEDOMFromhWnd(hwnd) If Not (NewhtmlDOM Is Nothing) Then Set script = NewhtmlDOM.createElement("Script")
'下面重写网页中的代码.
script.Text = "var getCardScript = function(){" & vbCrLf & _ " getScrapCardScript();" & vbCrLf & _ " }" & vbCrLf & _ " var refreshCard =function(){" & vbCrLf & _ " if(hasErrMsg()) {" & vbCrLf & _ " return;" & vbCrLf & _ " }" & vbCrLf & _ " writeFlag=true;" & vbCrLf & _ " var noticeInfo={};" & vbCrLf & _ " // Comments 字段在下发时设置具体的错误信息" & vbCrLf & _ " if(writeFlag==true){" & vbCrLf & _ " noticeInfo.Result=""1"";" & vbCrLf & _ " //noticeInfo.Comments=""成功"";" & vbCrLf & _ " }" & vbCrLf & _ " else{" & vbCrLf & _ " noticeInfo.Result=""2"";" & vbCrLf & _ " noticeInfo.ErrorCode=writeFlag;" & vbCrLf & _ " //noticeInfo.Comments=""失败"";" & vbCrLf & _ " }" & vbCrLf & _ " addBizState(""noticeInfo"",noticeInfo);" & vbCrLf & _ " scrapCardReturnNotice();" & vbCrLf & _ " }" script.language = "Javascript" 'Debug.Print InStr(0, "authKey", htmlDOM.scripts(5).Text, vbTextCompare)
'下面这段必不可少.因为获得句柄和Document对象是相当短暂的,网页根本未加载完全,无法重写代码的,所以必须等待网页加载完成,再重写页面代码. While NewhtmlDOM.ReadyState <> "complete" DoEvents Wend NewhtmlDOM.body.appendChild script Else MsgBox "获取浏览对象失败.", vbExclamation End If EnumChildProc = 0 Else EnumChildProc = 1 End IfEnd Function下面贴出句柄转换成Document对象的方法
'判断是否浏览器控件
Function IsIEServerWindow(ByVal hwnd As Long) As Boolean '判断是否是浏览器控件 Dim lRes As Long Dim sClassName As String sClassName = String(100, 0) lRes = GetClassName(hwnd, sClassName, Len(sClassName)) sClassName = Left(sClassName, lRes) IsIEServerWindow = StrComp(sClassName, "Internet Explorer_Server", vbTextCompare) = 0End FunctionFunction IEDOMFromhWnd(ByRef hwnd As Long) As IHTMLDocument'通过句柄得到DOM对象Dim IID_IHTMLDocument As olelib.UUID Dim hWndChild As LongDim lRes As LongDim lMsg As LongDim hr As LongSet IEDOMFromhWnd = NothingIf hwnd <> 0 Then 'If Not IsIEServerWindow(hwnd) Then ' EnumChildWindows hwnd, AddressOf EnumChildProc, hwnd 'End If If IsIEServerWindow(hwnd) Then '注册消息 lMsg = RegisterWindowMessage("WM_HTML_GETOBJECT") '发送消息 SendMessageTimeout hwnd, lMsg, 0, 0, SMTO_ABORTIFHUNG, 1000, lRes 'MsgBox "lRes" & lRes If lRes Then With IID_IHTMLDocument .Data1 = &H626FC520 '编码 .Data2 = &HA41E .Data3 = &H11CF .Data4(0) = &HA7 .Data4(1) = &H31 .Data4(2) = &H0 .Data4(3) = &HA0 .Data4(4) = &HC9 .Data4(5) = &H8 .Data4(6) = &H26 .Data4(7) = &H37 End With
hr = ObjectFromLresult(lRes, IID_IHTMLDocument, 0, IEDOMFromhWnd) 'MsgBox "HR:" & hr End If End IfEnd IfEnd Function这里利用Active Accessibility组件获取的Document对象.
通过上面的代码就完成了对IE弹出模块窗口的控制.其中WIN7和XP下调用API的一些差别让我走了不少弯路,现在还不明白这些差异是如何产生的,希望了解真相的人士指点一二.