Winform 限制单实例运行

 using System;

    
 using System.Collections.Generic;
    
 using System.Linq;
    
 using System.Reflection;
    
 using System.Threading;
    
 using System.Windows.Forms;
    
  
    
 namespace Winform.IdCardHelper
    
 {
    
     static class Program
    
     {
    
     private static Mutex _singleton;
    
  
    
     /// <summary>
    
     /// 应用程序的主入口点。
    
     /// </summary>
    
     [STAThread]
    
     static void Main()
    
     {
    
         Application.EnableVisualStyles();
    
         Application.SetCompatibleTextRenderingDefault(f