Junstyle's Blog

如何让window运用程序只有一个实例，重复运行即会显示以前打开的实例。

using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Reflection;   

namespace Junstyle
{
    static class Program
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            if( Exist() )
            {
                Application.Exit();
                return;
            }   

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

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

        public static bool Exist()
        {
            bool ret = false;
            Process current = Process.GetCurrentProcess();
            Process[] processes = Process.GetProcessesByName( current.ProcessName );
            //遍历与当前进程名称相同的进程列表
            foreach( Process process in processes )
            {
                //Ignore the current process
                if( process.Id != current.Id )
                {   

                    if( Assembly.GetExecutingAssembly().Location.Replace( "/", "\\" ) == current.MainModule.FileName )
                    {
                        ShowWindowAsync( process.MainWindowHandle, 1 ); //调用api函数，正常显示窗口
                        SetForegroundWindow( process.MainWindowHandle ); //将窗口放置最前端。
                        return true;
                    }
                }
            }
            return ret;
        }
    }
}