dajiaoyan-scanner/DaJiaoYan/Program.cs

using DaJiaoYan.Utils;
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
using System.Windows.Forms;

namespace DaJiaoYan
{
    internal static class Program
    {
        [STAThread]
        [DllImport("User32.dll")]
        private static extern bool ShowWindowAsync(System.IntPtr hWnd, int cmdShow);
        [DllImport("User32.dll")]
        private static extern bool SetForegroundWindow(System.IntPtr hWnd);

        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Process current = Process.GetCurrentProcess();
            Process instance = ProcessExts.RunningInstance(ref current);
            if (instance == null)
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new FormMain());
            }
            else
            {
                HandleRunningInstance(instance);
            }
        }

        #region  确保程序只运行一个实例
        private static void HandleRunningInstance(Process instance)
        {
            MessageBox.Show("程序已经在运行！", "提示信息", MessageBoxButtons.OK, MessageBoxIcon.Information);
            ShowWindowAsync(instance.MainWindowHandle, 1);  //调用api函数，正常显示窗口
            SetForegroundWindow(instance.MainWindowHandle); //将窗口放置最前端
        }
        #endregion
    }
}