C#枚举窗口句柄

在CS程序中启动其他应用后，要获取进程的主窗体其实很简单：

        Process p = Process.Start(exePath);
        //p.WaitForInputIdle();
        p.Refresh(); 
        IntPtr mainWnd = p.MainWindowHandle;

但是，总有很多特殊的情况，上面的方法根本无法用，所以，要用Windows API来搞定了

1、如果窗口信息很固定而且没有重名的话，可以用Findwindow搞定

        [DllImport("User32.dll", EntryPoint = "FindWindow")]
        public static extern IntPtr FindWindow(string lpClassName, string lpWindowName);
        IntPtr clientWnd = FindWindow(null,"FormClient");

2、根据标题枚举窗口句柄

        //枚举窗体
        [DllImport("User32.dll", EntryPoint = "EnumWindows", SetLastError = true)]
        public static extern bool EnumWindows(WNDENUMPROC lpEnumFunc, uint lParam);
        //获取窗体标题
        [DllImport("user32.dll", CharSet = CharSet.Auto)]
        static extern int GetWindowText(IntPtr hWnd, StringBuilder lpText, int nCount);
        //设置错误状态
        [DllImport("kernel32.dll", EntryPoint = "SetLastError")]
        public static extern void SetLastError(uint dwErrCode);

        //线程主窗口句柄
        private static IntPtr processMainWnd = IntPtr.Zero;
        //要查找的窗口名称
        private static String winTitle = "__Web__Form__Main__";

        //声明委托函数
        public delegate bool WNDENUMPROC(IntPtr hwnd, uint lParam);

        //枚举进程句柄，非线程安全
        [SecuritySafeCritical]
        public static IntPtr GetCurrentWindowHandle()
        {
            IntPtr ptrWnd = IntPtr.Zero;

            bool bResult = EnumWindows(new WNDENUMPROC(EnumWindowsProc), (uint)0);
            if (!bResult && Marshal.GetLastWin32Error() == 0)
            {
                ptrWnd = processMainWnd;
            }

            return ptrWnd;
        }

        //枚举函数，获取主窗口句柄然后退出
        [SecuritySafeCritical]
        private static bool EnumWindowsProc(IntPtr hwnd, uint lParam)
        {
            //根据标题获取窗体
            var sb = new StringBuilder(50);
            GetWindowText(hwnd, sb, sb.Capacity);

            if (winTitle.Equals(sb.ToString()))
            {
                processMainWnd = hwnd;
                SetLastError(0);
                return false;
            }

            return true;
        }

3、跟进进程id枚举获取主窗体句柄

        //枚举窗体
        [DllImport("User32.dll", EntryPoint = "EnumWindows", SetLastError = true)]
        //获取父窗体
        [DllImport("user32.dll", EntryPoint = "GetParent", SetLastError = true)]
        //根据窗口获取线程句柄
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern int GetWindowThreadProcessId(IntPtr hwnd, out uint pid);
        //设置错误状态
        [DllImport("kernel32.dll", EntryPoint = "SetLastError")]
        public static extern void SetLastError(uint dwErrCode);

        //线程主窗口句柄
        private static IntPtr processMainWnd = IntPtr.Zero;

        //枚举进程句柄
        [SecuritySafeCritical]
        public static IntPtr GetCurrentWindowHandle(int processId)
        {
            IntPtr ptrWnd = IntPtr.Zero;

            bool bResult = EnumWindows(new WNDENUMPROC(EnumWindowsProc), (uint)processId);
            if (!bResult && Marshal.GetLastWin32Error() == 0)
            {
                ptrWnd = processMainWnd;
            }

            return ptrWnd;
        }

        //枚举函数，获取主窗口句柄然后退出
        [SecuritySafeCritical]
        private static bool EnumWindowsProc(IntPtr hwnd, uint lParam)
        {
            uint uiPid = 0;
            //根据启动方式不同，这里要有相应修改
            if (GetParent(hwnd) == IntPtr.Zero)
            {
                GetWindowThreadProcessId(hwnd, out uiPid);
                if (uiPid == lParam)
                {
                    processMainWnd = hwnd;
                    SetLastError(0);
                    return false;
                }
            }
        }

4、跟进窗口WindowsClassName举获取主窗体句柄

        //查找桌面
        [DllImport("User32.dll", ExactSpelling = true, CharSet = CharSet.Ansi, SetLastError = true)]
        public static extern IntPtr GetDesktopWindow();
        //获取窗体句柄
        [DllImport("User32.dll", CharSet = CharSet.Auto, SetLastError = true, ExactSpelling = true)]
        public static extern IntPtr GetWindow(IntPtr hwnd, int wFlag);
        //获取窗体类
        [DllImport("User32.dll", CharSet = CharSet.Auto)]
        public static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);

        public const int GW_CHILD = 5;
        public const int GW_HWNDNEXT = 2;

        //枚举桌面窗口，根据WindowsClassName获取句柄
        [SecuritySafeCritical]
        public static IntPtr GetWinHandleByClasName(String windowClassNmae)
        {   
            //取得桌面窗口，再获取第一个子窗口
            IntPtr hwnd = GetDesktopWindow();
            hwnd = GetWindow((IntPtr)hwnd, System.Convert.ToInt32(GW_CHILD));
            
            //通过循环来枚举所有的子窗口
            while ((long)hwnd != 0)
            {
                System.Text.StringBuilder ClassName = new System.Text.StringBuilder(256);
                GetClassName((IntPtr)hwnd, ClassName, ClassName.Capacity);
                String tmpClassName= ClassName.ToString().Trim();
                if (tmpClassName.Length > 0)
                {
                    if (tmpClassName.Equals(windowClassNmae))
                    {
                        break;
                    }
                }

                hwnd = GetWindow((IntPtr)hwnd, System.Convert.ToInt32(GW_HWNDNEXT));
            }

            return hwnd;
        }