C#獲取進程的主窗口句柄的實現方法

通過調用Win32 API實現。

public class User32API
{
    private static Hashtable processWnd = null;
    public delegate bool WNDENUMPROC(IntPtr hwnd, uint lParam);
    static User32API()
    {
        if (processWnd == null)
        {
            processWnd = new Hashtable();
        }
    }
    [DllImport("user32.dll", EntryPoint = "EnumWindows", SetLastError = true)]
    public static extern bool EnumWindows(WNDENUMPROC lpEnumFunc, uint lParam);
    [DllImport("user32.dll", EntryPoint = "GetParent", SetLastError = true)]
    public static extern IntPtr GetParent(IntPtr hWnd);
    [DllImport("user32.dll", EntryPoint = "GetWindowThreadProcessId")]
    public static extern uint GetWindowThreadProcessId(IntPtr hWnd, ref uint lpdwProcessId);
    [DllImport("user32.dll", EntryPoint = "IsWindow")]
    public static extern bool IsWindow(IntPtr hWnd);
    [DllImport("kernel32.dll", EntryPoint = "SetLastError")]
    public static extern void SetLastError(uint dwErrCode);
    public static IntPtr GetCurrentWindowHandle()
    {
        IntPtr ptrWnd = IntPtr.Zero;
        uint uiPid = (uint)Process.GetCurrentProcess().Id;  // 當前進程 ID
        object objWnd = processWnd[uiPid];
        if (objWnd != null)
        {
            ptrWnd = (IntPtr)objWnd;
            if (ptrWnd != IntPtr.Zero && IsWindow(ptrWnd))  // 從緩存中獲取句柄
            {
                return ptrWnd;
            }
            else
            {
                ptrWnd = IntPtr.Zero;
            }
        }
        bool bResult = EnumWindows(new WNDENUMPROC(EnumWindowsProc), uiPid);
        // 枚舉窗口返回 false 並且沒有錯誤號時表明獲取成功
        if (!bResult && Marshal.GetLastWin32Error() == 0)
        {
            objWnd = processWnd[uiPid];
            if (objWnd != null)
            {
                ptrWnd = (IntPtr)objWnd;
            }
        }
        return ptrWnd;
    }
    private static bool EnumWindowsProc(IntPtr hwnd, uint lParam)
    {
        uint uiPid = 0;
        if (GetParent(hwnd) == IntPtr.Zero)
        {
            GetWindowThreadProcessId(hwnd, ref uiPid);
            if (uiPid == lParam)    // 找到進程對應的主窗口句柄
            {
                processWnd[uiPid] = hwnd;   // 把句柄緩存起來
                SetLastError(0);    // 設置無錯誤
                return false;   // 返回 false 以終止枚舉窗口
            }
        }
        return true;
    }
} 

調用User32API.GetCurrentWindowHandle()即可返回當前進程的主窗口句柄，如果獲取失敗則返回IntPtr.Zero。