WinFrom单例启动

    /// <summary>
    /// WinFrom单例启动示例
    /// </summary>
    static class Program2
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Process instance = RunningInstance();
            if (instance == null)
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
            }
            else
            {
                HandleRunningInstance(instance);
            }
        }

        /// <summary> 
        /// 显示已运行的程序。 
        /// </summary> 
        public static void HandleRunningInstance(Process instance)
        {
            ShowWindowAsync(instance.MainWindowHandle, WS_SHOWNORMAL); //显示，可以注释掉 
            SetForegroundWindow(instance.MainWindowHandle);            //放到前端 
        }

        /// <summary> 
        /// 获取正在运行的实例，没有运行的实例返回null; 
        /// </summary> 
        public static Process RunningInstance()
        {
            try
            {
                Process current = Process.GetCurrentProcess();
                Process[] processes = Process.GetProcessesByName(current.ProcessName);

                foreach (Process process in processes)
                {
                    if (process.Id != current.Id)
                    {
                        string title = process.MainWindowTitle;
                        if (title == "") // 进程无主窗口
                        {
                            try {
                                process.Kill();
                            }catch { }
                        }
                        else
                        {
                            if (process.MainModule.FileName == current.MainModule.FileName) // 若为当前路径下的exe
                                return process;
                            else if(!process.CloseMainWindow()) // 非当前路径下的exe通知其退出
                            {
                                try {
                                    process.Kill();
                                }catch { }
                            }
                        }
                    }
                }
                return null;
            }
            catch (Exception e)
            {
                return null;
            }
        }

        /// <summary> 
        /// 获取正在运行的实例，没有运行的实例返回null; 
        /// </summary> 
        public static Process RunningInstance0()
        {
            Process current = Process.GetCurrentProcess();
            //File.WriteAllText("当前进程名称.txt", current.ProcessName);
            Process[] processes = Process.GetProcessesByName(current.ProcessName);
            foreach (Process process in processes)
            {
                if (process.Id != current.Id)
                {
                    //File.AppendAllText("当前进程名称.txt", "Location:" + Assembly.GetEntryAssembly().Location.Replace("/", "\\") + "\r\n" + "FileName:" + current.MainModule.FileName);
                    if (Assembly.GetEntryAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)
                    {
                        return process;
                    }
                }
            }
            return null;
        }


        /// <summary> 
        /// 该函数设置由不同线程产生的窗口的显示状态。 
        /// </summary> 
        /// <param name="hWnd">窗口句柄</param> 
        /// <param name="cmdShow">指定窗口如何显示。查看允许值列表，请查阅ShowWlndow函数的说明部分。</param> 
        /// <returns>如果函数原来可见，返回值为非零；如果函数原来被隐藏，返回值为零。</returns> 
        [DllImport("User32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);

        /// <summary> 
        /// 该函数将创建指定窗口的线程设置到前台，并且激活该窗口。键盘输入转向该窗口，并为用户改各种可视的记号。系统给创建前台窗口的线程分配的权限稍高于其他线程。 
        /// </summary> 
        /// <param name="hWnd">将被激活并被调入前台的窗口句柄。</param> 
        /// <returns>如果窗口设入了前台，返回值为非零；如果窗口未被设入前台，返回值为零。</returns> 
        [DllImport("User32.dll")]
        private static extern bool SetForegroundWindow(IntPtr hWnd);
        private const int WS_SHOWNORMAL = 1;

    }