【C#】 实现WinForm中只能启动一个实例

如代码所示：

方法一：

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

namespace ProcessBarTest
{
    static class Program
    {
        private const int SW_SHOW = 5;

        [DllImport("User32.dll")]
        private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);

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

            Process p = RunningInstance();
            if (p == null)
            {
                Application.Run(new MainForm());
            }
            else
            {
                HandleRunningInstance(p);
            }
        }

        /// <summary>
        /// Get current process
        /// </summary>
        /// <returns></returns>
        private static Process RunningInstance()
        {
            Process currentProcess = Process.GetCurrentProcess();
            Process[] processByName = Process.GetProcessesByName(currentProcess.ProcessName);
            return processByName.FirstOrDefault(process2 => (process2.Id != currentProcess.Id) && (Assembly.GetExecutingAssembly().Location.Replace("/", @"") == currentProcess.MainModule.FileName));
        }

        private static void HandleRunningInstance(Process p)
        {
            MessageBox.Show("已经有一个实例在运行，一台电脑只能运行一个实例！");
            ShowWindowAsync(p.MainWindowHandle, SW_SHOW);
        }
    }
}

 方法二：

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

namespace LANChat_UI
{
    static class Program
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);

            bool bIsRunning;
            Mutex mutexApp = new Mutex(false, Assembly.GetExecutingAssembly().FullName, out bIsRunning);
            if (!bIsRunning)
            {
                MessageBox.Show("聊天程序正在运行，系统只能运行一个聊天实例！");
            }
            else
            {
                MainForm mainForm = new MainForm();
                mainForm.Text = Environment.UserName.ToString();
                Application.Run(mainForm);
            }            
        }
    }
}