C# winform判断自身程序是否已运行，如果已运行则激活窗体

C# winform判断自身程序是否已运行，如果已运行则激活窗体

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

namespace WindowsFormsApp1
{
    internal static class Program
    {
        [DllImport("user32.dll")]
        public static extern void SwitchToThisWindow(IntPtr hWnd, bool fAltTab);
        /// 

        /// 应用程序的主入口点。
        /// 
        [STAThread]
        static void Main()
        {
            Process currentProcess = Process.GetCurrentProcess();

            Process[] processes = Process.GetProcessesByName(currentProcess.ProcessName);
            if (processes.Length > 1)
            {
                //MessageBox.Show("此软件已经在运行！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                IntPtr handle = GetOldProcess(processes, currentProcess).MainWindowHandle;
                SwitchToThisWindow(handle, true);    // 激活，显示在最前  

                Thread.Sleep(1000);
                Environment.Exit(1);
            }



            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());
        }

        /// 

        /// 获取老的进程
        /// 
        /// 
        /// 
        private static Process GetOldProcess(Process[] processes, Process currentProcess)
        {
            //遍历与当前进程名称相同的进程列表
            foreach (Process process in processes)
            {
                //如果实例已经存在则忽略当前进程
                if (process.Id != currentProcess.Id)
                {
                    //返回已经存在的进程
                    return process;
                }
            }
            return null;
        }
    }
}