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 < 2)
                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() != "0")//不等于0表示找到了窗体
                    SetForegroundWindow(ptr);

                Application.Exit();
            }
        }
    }
}