Question

我有一个应用程序，我已成功应用互斥锁，以确保只有一个应用程序实例一次运行。它几乎是解决方案的直接副本：What is the correct way to create a single-instance application?

问题在于第二个实例的命令行参数。我想将它传递给第一个实例，我决定尝试使用MemoryMappedFile来实现这一目标。我已经修改了上面的互斥解决方案来尝试实现这一点，但是在尝试＆＃34; OpenExisting＆＃34;时我得到了一个FileNotFoundException。我尝试了许多不同的解决方案来尝试解决这个问题，但似乎都没有。我做错了什么？（我打算把这个arg写给MMF，但是现在我只是用二进制文件作为测试）：

namespace MyApplication
{
    static class Program
    {

        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        static Mutex mutex = new Mutex(true, "{E6FD8A59-1754-4EA5-8996-2F1BC3AC5D87}");
        [STAThread]
        static void Main(string[] args)
        {
            if (mutex.WaitOne(TimeSpan.Zero, true))
            {
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);

                if (args.Length == 1)
                {
                    Application.Run(new Form1(args[0]));
                }
                else
                {
                    Application.Run(new Form1());
                }

                mutex.ReleaseMutex();
            }
            else
            {
                NativeMethods.PostMessage((IntPtr)NativeMethods.HWND_BROADCAST, NativeMethods.WM_SHOWME, IntPtr.Zero, IntPtr.Zero);

                if (args.Length == 1)
                {
                    if (File.Exists(args[0]))
                    {
                        MemoryMappedFile mmf = MemoryMappedFile.CreateNew("filetoopen", 10000);

                        using (MemoryMappedViewStream stream = mmf.CreateViewStream())
                        {
                            BinaryWriter writer = new BinaryWriter(stream);
                            writer.Write(1);
                        }
                        NativeMethods.PostMessage((IntPtr)NativeMethods.HWND_BROADCAST, NativeMethods.WM_OPENFILE, IntPtr.Zero, IntPtr.Zero);

                    }
                }
            }
        }
    }

    internal class NativeMethods
    {
        public const int HWND_BROADCAST = 0xffff;
        public static readonly int WM_SHOWME = RegisterWindowMessage("WM_SHOWME");
        public static readonly int WM_OPENFILE = RegisterWindowMessage("WM_OPENFILE");
        [DllImport("user32.dll")]
        public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);
        [DllImport("user32.dll")]
        public static extern int RegisterWindowMessage(string message);
    }
}

Form1中的相关代码：

protected override void WndProc(ref Message m)
{
    if (m.Msg == NativeMethods.WM_SHOWME)
    {
            ShowMe(); //This works fine. Method excluded.
    }
    else if (m.Msg == NativeMethods.WM_OPENFILE)
    {

       try
       {
            MemoryMappedFile mmf = MemoryMappedFile.OpenExisting("Global\\filetoopen"); 
            using (MemoryMappedViewStream stream = mmf.CreateViewStream())
            {
                BinaryReader reader = new BinaryReader(stream);
                MessageBox.Show(reader.ReadBoolean().ToString());
            }
       }
       catch (FileNotFoundException)
       {
           MessageBox.Show("File not found.");
       }

    }
    base.WndProc(ref m);
}

MemoryMappedFile - 传递命令行参数

0 个答案: