C# 通过进程名/进程Id 操作窗口/程序

1. 判断窗口是否存在

    private bool IsWindowExist(IntPtr handle)
    {
        return (!(GetWindow(new HandleRef(this, handle), 4) != IntPtr.Zero) && IsWindowVisible(new HandleRef(this, handle)));
    }

    [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
    public static extern IntPtr GetWindow(HandleRef hWnd, int uCmd);

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    public static extern bool IsWindowVisible(HandleRef hWnd);

2. 获取窗口句柄

    /// <summary>
    /// 获取应用程序窗口句柄
    /// </summary>
    /// <param name="processId"></param>
    /// <returns></returns>
    private IntPtr GetWindowHandle(int processId)
    {
        var windowHandle = IntPtr.Zero;
        EnumThreadWindowsCallback windowsCallback = new EnumThreadWindowsCallback(FindMainWindow);
        EnumWindows(windowsCallback, IntPtr.Zero);
        //保持循环
        GC.KeepAlive(windowsCallback);

        bool FindMainWindow(IntPtr handle, IntPtr extraParameter)
        {
            int num;
            GetWindowThreadProcessId(new HandleRef(this, handle), out num);
            if (num == processId && IsWindowExist(handle))
            {
                windowHandle = handle;
                return true;
            }
            return false;
        }

        return windowHandle;
    }
    public delegate bool EnumThreadWindowsCallback(IntPtr hWnd, IntPtr lParam);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern bool EnumWindows(EnumThreadWindowsCallback callback, IntPtr extraData);

    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
    public static extern int GetWindowThreadProcessId(HandleRef handle, out int processId);

3. 关闭应用窗口

根据进程Id关闭应用窗口：

    /// <summary>
    /// 关闭程序主窗口
    /// </summary>
    /// <param name="processId">进程ID</param>
    public void CloseWindow(int processId)
    {
        var mwh = GetWindowHandle(processId);
        SendMessage(mwh, MW_CLOSE, 0, 0);
    }
    const int MW_CLOSE = 0x0010;

    [DllImport("User32.dll", EntryPoint = "SendMessage")]
    private static extern int SendMessage(IntPtr hWnd, int Msg, int wParam, int lParam);

关闭所有此进程名的窗口：

        public void CloseAllWindows(string processName)
        {
            Process[] processList = Process.GetProcessesByName(processName);
            foreach (Process process in processList)
            {
                CloseMainWindow(process.Id);
            }
        }

当然，直接杀进程，是最快的方法：

    /// <summary>
    /// 关闭所有进程
    /// </summary>
    /// <param name="processName"></param>
    /// <returns></returns>
    public static bool CloseAllProcesses(string processName)
    {
        try
        {
            Process[] psEaiNotes = Process.GetProcessesByName(processName);
            foreach (Process psEaiNote in psEaiNotes)
            {
                psEaiNote.Kill();
            }
        }
        catch
        {
            return false;
        }

        return true;
    }

4. 重启程序

    string appFileName = currentClientProcess.MainModule.FileName;

    Process newClient = new Process();
    newClient.StartInfo.FileName = appFileName;
    // 设置要启动的进程的初始目录
    newClient.StartInfo.WorkingDirectory = System.Windows.Forms.Application.ExecutablePath;
    
    //启动程序
    currentClientProcess.Kill();
    newClient.Start();

窗口之间发送/接收消息的处理，请参考《C# 跨进程通信》