WinFrom 只启动一个exe，并且获得焦点

只启动一个exe方法：

 using System;
 using System.Collections.Generic;
 using System.Runtime.InteropServices;
 using System.Windows.Forms;

 namespace StringToImage
 {
     static class Program
     {
         [DllImport("user32.dll")]
         public static extern IntPtr FindWindow(String classname, String title);
         [DllImport("user32.dll")]
         public static extern void SetForegroundWindow(IntPtr hwnd);

         [STAThread]
         static void Main()
         {
             Application.EnableVisualStyles();
             Application.SetCompatibleTextRenderingDefault(false);

             string p = System.Diagnostics.Process.GetCurrentProcess().ProcessName;
             System.Diagnostics.Process[] processes = System.Diagnostics.Process.GetProcessesByName(p);
             if (processes.Length < )
                 Application.Run(new Form1());
             else
             {
                 //MessageBox.Show("程序已经运行!", "系统提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
                 IntPtr ptr = FindWindow(null, "文字转换成图片");//"文字转换成图片"为对应窗体的Text值
                 if (ptr.ToString() != "")//不等于0表示找到了窗体
                     SetForegroundWindow(ptr);

                 Application.Exit();
             }
         }
     }
 }