C#:只运行一个程序

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Threading;
using System.Runtime.InteropServices;

namespace Example
{
    public class SinglonProgram
    {

        #region 字段

        //显示的主窗体
        private Form mainForm;

        //线程同步事件
        private static EventWaitHandle programWaitHandle;

        #endregion

        #region 属性

        #endregion

        #region 构造函数

        public SinglonProgram(Form showForm)
        {
            this.mainForm = showForm;

            //注册一个等待WaitHandle的委托
            ThreadPool.RegisterWaitForSingleObject(programWaitHandle, (obj, timeOut) =>
            {
                ShowForm();
            },
            null, -1, false);

        }

        #endregion

        #region 私有函数  显示窗体、等

        /// <summary>
        /// 显示窗体
        /// </summary>
        private void ShowForm()
        {
            //在拥有mainForm窗体的线程上执行无参委托（Action）
            this.mainForm.Invoke(new Action(() =>
                {
                    this.mainForm.Visible = true;
                    if(this.mainForm.WindowState == FormWindowState.Minimized)
                    {
                        this.mainForm.WindowState = FormWindowState.Normal;
                    }
                    this.mainForm.Show();

                    bool isForeground = SetForegroundWindow(this.mainForm.Handle);
                    MessageBox.Show(isForeground.ToString());
                }
            ));
        }

        #endregion

        #region 公共函数  只有一个程序运行

        /// <summary>
        /// 是否创建了已命名的系统事件
        /// </summary>
        /// <returns></returns>
        public static bool isNamedSystemEvent()
        {
            bool createdNew;
            programWaitHandle = new EventWaitHandle(true, EventResetMode.AutoReset, Application.ProductName, out createdNew);
            return !createdNew;
        }

        /// <summary>
        /// 确保只有一个程序运行
        /// </summary>
        public static void Confirm()
        {
            // 如果该命名事件已命名(运行实例已经存在)，则发事件通知并退出
            if (isNamedSystemEvent())
            {
                programWaitHandle.Set();    //将事件状态设置为终止状态，允许一个或多个等待线程继续
                Environment.Exit(1);
            }
        }

        #endregion

        #region 接口函数 激活窗体且前端显示等

        /// <summary>
        /// 前端显示且激活窗体
        /// </summary>
        /// <param name="hWnd">窗体句柄</param>
        /// <returns></returns>
        [DllImport("user32.dll")]
        public static extern bool SetForegroundWindow(IntPtr hWnd);


        #endregion

        #region 虚函数

        #endregion
    }
}

 static class Program
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            SinglonProgram.Confirm();
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new frmMain());
        }
    }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Reflection;

namespace Test
{
    static class Program
    {
        /// <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;


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

        }

        /// <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()
        {
            Process current = Process.GetCurrentProcess();
            Process[] processes = Process.GetProcessesByName(current.ProcessName);
            foreach (Process process in processes)
            {
                if (process.Id != current.Id)
                {
                    if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)
                    {
                        return process;
                    }
                }
            }
            return null;
        }

        /// <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>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Process instance = RunningInstance();

            bool blnIsRunning;
            Mutex mutexApp = new Mutex(false, Assembly.GetExecutingAssembly().FullName, out blnIsRunning);
            if (!blnIsRunning)
            {
                MessageBox.Show("程序已经运行！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                return;
            }   

            Application.Run(new Form1());

        }

public void A()
        {
            //=====创建互斥体法：=====
            bool blnIsRunning;
            Mutex mutexApp = new Mutex(false, Assembly.GetExecutingAssembly().FullName, out blnIsRunning);
            if (!blnIsRunning)
            {
                MessageBox.Show("程序已经运行！", "提示",MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                return;
            }   
        }

        public void B()
        {
            //保证同时只有一个客户端在运行   
            System.Threading.Mutex mutexMyapplication = new System.Threading.Mutex(false, "OnePorcess.exe");
            if (!mutexMyapplication.WaitOne(100, false))
            {
                MessageBox.Show("程序" + Application.ProductName + "已经运行！", Application.ProductName,
                MessageBoxButtons.OK, MessageBoxIcon.Error);
                return;
            }
        }

        public void c()
        {
            //=====判断进程法：(修改程序名字后依然能执行)=====
            Process current = Process.GetCurrentProcess();
            Process[] processes = Process.GetProcessesByName(current.ProcessName);
            foreach (Process process in processes)
            {
                if (process.Id != current.Id)
                {
                    if (process.MainModule.FileName == current.MainModule.FileName)
                    {
                        MessageBox.Show("程序已经运行！", Application.ProductName,
                        MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                        return;
                    }
                }
            }
        }