C#仅允许一个程序实例运行

方法1.按如下代码更改

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

namespace WindowsFormsApplicationTest
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);

            //防止启动多个应用和序
            if (RunningInstance() != null)
            {
                System.Windows.Forms.MessageBox.Show("已经有一个程序在运行");
                return;
            }

            Application.Run(new Form1());
        }

        public static Process RunningInstance()
        {
            Process current = Process.GetCurrentProcess();
            Process[] processes = Process.GetProcessesByName(current.ProcessName);

            //Loop through the running processes in with the same name
            foreach (Process process in processes)
            {
                //Ignore the current process
                if (process.Id != current.Id)
                {
                    //Make sure that the process is running from the exe file.
                    if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)
                    {
                        //Return the other process instance.
                        return process;
                    }
                }

            }
            //No other instance was found, return null.
            return null;

        } 
    }
}

方法2

using System;
using System.Collections.Generic;
using System.Windows.Forms;
using System.Threading;

namespace TestForm.TreeViewAndMDIForm
{
    static class Program
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            bool createdNew;
            Mutex m = new Mutex(true, "test", out createdNew);
            if (createdNew)
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
                m.ReleaseMutex();
            }
            else
            {

                MessageBox.Show("系统只允许运行一个实例！", "系统提示");

            }
        }
    }
}