用axWebBrowser加载HTML网页时，真正显示内容的窗体并不是axWebBrowser，而是其子窗口的子窗口一个名为Internet Explorer_Server的类。从spy++可知：
公司需要在网页上进行手写，需要对Internet Explorer_Server进行操作，而通过axWebBrowser的Handle不能直接操作Internet Explorer_Server。于是在网上搜到Paul DiLascia写的一个CFindWnd类，是用C++写的，由于我用C#进行了改写。
这个类主要用的的API 是EnumChildWindows和FindWindowEx，第一个遍历指定窗口下的子窗口，第二个查找指定名称的窗口，如果找到返回此窗口Handle。
该类的用法：
FindWindow fw = new FindWindow(wndHandle, "ChildwndClassName"); //实例化，第一个参数是要查找的起始窗口的句柄；第二个参数是要查找的窗口的类的名称。现在我们需要的传的是"Internet Explorer_Server"。
IntPtr ip = fw.FoundHandle;//FindWindow的公共属性FoundHandle就是查找到的窗口的句柄。
完整的类如下：
using System; using System.Collections.Generic; using System.Text; using System.Runtime.InteropServices; namespace SystemManager.Utility
... { 
/**//// <summary>
/// This class is to find the given window's child window accroding to the given child window's name. /// The useage: FindWindow fw = new FindWindow(wndHandle, "ChildwndClassName"); IntPtr ip = fw.FoundHandle; /// I adapt the code from Paul DiLascia,who is the MSDN Magazine's writer. /// The original class is named CFindWnd which is written in C++, and you could get it on Internet. /// www.pinvoke.net is a great website.It includes almost all the API fuctoin to be used in C#.
/// </summary> class FindWindow ...{ [DllImport("user32")] [return: MarshalAs(UnmanagedType.Bool)] //IMPORTANT : LPARAM must be a pointer (InterPtr) in VS2005, otherwise an exception will be thrown private static extern bool EnumChildWindows(IntPtr window, EnumWindowProc callback, IntPtr i); //the callback function for the EnumChildWindows private delegate bool EnumWindowProc(IntPtr hWnd, IntPtr parameter); //if found return the handle , otherwise return IntPtr.Zero [DllImport("user32.dll", EntryPoint = "FindWindowEx")] private static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow); private string m_classname; // class name to look for private IntPtr m_hWnd; // HWND if found public IntPtr FoundHandle ...{ get ...{ return m_hWnd; } } // ctor does the work--just instantiate and go public FindWindow(IntPtr hwndParent, string classname) ...{ m_hWnd = IntPtr.Zero; m_classname = classname; FindChildClassHwnd(hwndParent, IntPtr.Zero); } /**//// <summary> /// Find the child window, if found m_classname will be assigned /// </summary> /// <param name="hwndParent">parent's handle</param> /// <param name="lParam">the application value, nonuse</param> /// <returns>found or not found</returns> //The C++ code is that lParam is the instance of FindWindow class , if found assign the instance's m_hWnd private bool FindChildClassHwnd(IntPtr hwndParent, IntPtr lParam) ...{ EnumWindowProc childProc = new EnumWindowProc(FindChildClassHwnd); IntPtr hwnd = FindWindowEx(hwndParent, IntPtr.Zero, this.m_classname, string.Empty); if (hwnd != IntPtr.Zero) ...{ this.m_hWnd = hwnd; // found: save it return false; // stop enumerating } EnumChildWindows(hwndParent, childProc, IntPtr.Zero); // recurse redo FindChildClassHwnd return true;// keep looking } }
} 注意：在VS2005中，MDA检查的很严格，LPARAM是64位，要用IntPtr表示(网上有人用long来表示，我试了，MDA会抛出异常)。 是个不错的网站，它包含了几乎所有的API在.NET中的调用说明，还有例子。
附Paul DiLascia用C++写的CFindWnd类：
/**/ //// // MSDN Magazine -- August 2003 // If this code works, it was written by Paul DiLascia. // If not, I don't know who wrote it. // Compiles with Visual Studio .NET on Windows XP. Tab size=3. // // --- // This class encapsulates the process of finding a window with a given class name // as a descendant of a given window. To use it, instantiate like so: // // CFindWnd fw(hwndParent,classname); // // fw.m_hWnd will be the HWND of the desired window, if found. // class CFindWnd ... { private: /**/// // This private function is used with EnumChildWindows to find the child // with a given class name. Returns FALSE if found (to stop enumerating). // static BOOL CALLBACK FindChildClassHwnd(HWND hwndParent, LPARAM lParam) ...{ CFindWnd *pfw = (CFindWnd*)lParam; HWND hwnd = FindWindowEx(hwndParent, NULL, pfw->m_classname, NULL); if (hwnd) ...{ pfw->m_hWnd = hwnd; // found: save it return FALSE; // stop enumerating } EnumChildWindows(hwndParent, FindChildClassHwnd, lParam); // recurse return TRUE; // keep looking } public: LPCSTR m_classname; // class name to look for HWND m_hWnd; // HWND if found // ctor does the work--just instantiate and go CFindWnd(HWND hwndParent, LPCSTR classname) : m_hWnd(NULL), m_classname(classname) ...{ FindChildClassHwnd(hwndParent, (LPARAM)this); } } ; 2009年更新
通过实验得知，FindWindowEx可以通过classname或caption（也就是窗口的title）查找窗口，且如果第一个参数传IntPtr.Zero的话，将从Windows最顶层窗口开始查找，但是窗口很多的话这样会非常的慢，所以加入Timeout的判断，如果超时还没找到，返回false。用法：FindWindow fw = new FindWindow(IntPtr.Zero, null, "ThunderDFrame", 10);//查找Title为ThunderDFrame的窗口，如果10秒内还没找到，返回false
代码如下：
using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.Runtime.InteropServices;namespace Util{ class FindWindow { [DllImport("user32")] [return: MarshalAs(UnmanagedType.Bool)] //IMPORTANT : LPARAM must be a pointer (InterPtr) in VS2005, otherwise an exception will be thrown private static extern bool EnumChildWindows(IntPtr window, EnumWindowProc callback, IntPtr i); //the callback function for the EnumChildWindows private delegate bool EnumWindowProc(IntPtr hWnd, IntPtr parameter); //if found return the handle , otherwise return IntPtr.Zero [DllImport("user32.dll", EntryPoint = "FindWindowEx")] private static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow); private string m_classname; // class name to look for private string m_caption; // caption name to look for private DateTime start; private int m_timeout;//If exceed the time. Indicate no windows found. private IntPtr m_hWnd; // HWND if found public IntPtr FoundHandle { get { return m_hWnd; } } private bool m_IsTimeOut; public bool IsTimeOut { get{ return m_IsTimeOut;} set { m_IsTimeOut = value; } } // ctor does the work--just instantiate and go public FindWindow(IntPtr hwndParent, string classname, string caption, int timeout) { m_hWnd = IntPtr.Zero; m_classname = classname; m_caption = caption; m_timeout = timeout; start = DateTime.Now; FindChildClassHwnd(hwndParent, IntPtr.Zero); } /**/ /// /// Find the child window, if found m_classname will be assigned /// /// parent's handle /// the application value, nonuse /// found or not found //The C++ code is that lParam is the instance of FindWindow class , if found assign the instance's m_hWnd private bool FindChildClassHwnd(IntPtr hwndParent, IntPtr lParam) { EnumWindowProc childProc = new EnumWindowProc(FindChildClassHwnd); IntPtr hwnd = FindWindowEx(hwndParent, IntPtr.Zero, m_classname, m_caption); if (hwnd != IntPtr.Zero) { this.m_hWnd = hwnd; // found: save it m_IsTimeOut = false; return false; // stop enumerating } DateTime end = DateTime.Now; if (start.AddSeconds(m_timeout) > end) { m_IsTimeOut = true; return false; } EnumChildWindows(hwndParent, childProc, IntPtr.Zero); // recurse redo FindChildClassHwnd return true;// keep looking } }}