protected override void OnStartup(StartupEventArgs e)

         {

             //禁止二次启动

             this.Startup += new StartupEventHandler(App_Startup);

             base.OnStartup(e);

         }

         #region 禁止二次启动

         // 用于激活已打开的窗体

         [DllImport("user32.dll")]

         public static extern void SetForegroundWindow(IntPtr hwnd);

         //操作当前窗体

         //nCmdShow: 0关闭窗口/1正常大小显示窗口/2最小化窗口/3最大化窗口

         [DllImport("user32.dll")]

         public static extern int ShowWindow(IntPtr hwnd, int nCmdShow);

         System.Threading.Mutex mutex;

         void App_Startup(object sender, StartupEventArgs e)

         {

             bool ret;

             mutex = new System.Threading.Mutex(true, "WpfDemo", out ret);

             if (!ret)

             {

                 System.Diagnostics.Process[] proc = System.Diagnostics.Process.GetProcessesByName("WpfDemo");

                 foreach (System.Diagnostics.Process p in proc)

                 {

                     SetForegroundWindow(p.MainWindowHandle);

                     ShowWindow(p.MainWindowHandle, );

                     NoSecond.SendMessage(p.MainWindowHandle);

                 }

                 Environment.Exit();

             }

         }

         #endregion

     /// <summary>

     /// 禁止程序二次启动

     /// </summary>

     public class WPFNoSecond

     {

         public const int NoSecond_DATA = 0x004A;

         [DllImport("User32.dll", EntryPoint = "SendMessage")]

         private static extern int SendMessage

         (

                 IntPtr hWnd,                   //目标窗体句柄

                 int Msg,                       //WM_COPYDATA

                 int wParam,                                             //自定义数值

                 ref  CopyDataStruct lParam             //结构体

         );

         [StructLayout(LayoutKind.Sequential)]

         public struct CopyDataStruct

         {

             public IntPtr dwData;

             public int cbData;//字符串长度

             [MarshalAs(UnmanagedType.LPStr)]

             public string lpData;//字符串

         }

         public static void SendMessage(IntPtr thisIntPtr)

         {

             IntPtr xmlIntPt = new IntPtr(GetIntPtr());

             if (xmlIntPt != IntPtr.Zero || thisIntPtr != IntPtr.Zero)

             {

                 CopyDataStruct cds;

                 cds.dwData = IntPtr.Zero;

                 cds.lpData = "";

                 cds.cbData = ;//注意：长度为字节数

                 int fromWindowHandler = ;// 消息来源窗体

                 SendMessage(thisIntPtr.ToInt32() ==  ? xmlIntPt : thisIntPtr, NoSecond_DATA, fromWindowHandler, ref  cds);

             }

         }

         #region 窗体句柄指针

         static string _IntPtrDataDic = AppDomain.CurrentDomain.BaseDirectory + "/XML/";

         static string _IntPtrDataName = "Data.xml";

         static void intPtrDataExists()

         {

             try

             {

                 if (!System.IO.File.Exists(_IntPtrDataDic))

                 {

                     if (!Directory.Exists(_IntPtrDataDic)) { Directory.CreateDirectory(_IntPtrDataDic); }

                     XmlDocument doc = new XmlDocument();

                     doc.AppendChild(doc.CreateXmlDeclaration("1.0", "utf-8", ""));

                     XmlElement root = doc.CreateElement("Root");

                     root.InnerText = "";

                     doc.AppendChild(root);

                     doc.Save(_IntPtrDataDic);

                 }

             }

             catch (Exception) { }

         }

         static int GetIntPtr()

         {

             intPtrDataExists();

             XDocument xml = XDocument.Load(_IntPtrDataDic + _IntPtrDataName);

             XElement xmlRoot = xml.Root;

             return Convert.ToInt32(xmlRoot.Value);

         }

         public static void SetIntPtr(string intPtr)

         {

             intPtrDataExists();

             XDocument xml = XDocument.Load(_IntPtrDataDic + _IntPtrDataName);

             XElement xmlRoot = xml.Root;

             xmlRoot.Value = intPtr;

             xml.Save(_IntPtrDataDic + _IntPtrDataName);

         }

         #endregion

     }

         #region 禁止二次启动

         private void Window_SourceInitialized(object sender, EventArgs e)

         {

             HwndSource source = HwndSource.FromHwnd(new WindowInteropHelper(this).Handle);

             if (source == null) { throw new Exception("Cannot get HwndSource instance."); }

             source.AddHook(new HwndSourceHook(this.WndProc));

         }

         private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)

         {

             try

             {

                 switch (msg)

                 {

                     case WPFNoSecond.NoSecond_DATA:

                         this.Show();

                         break;

                 }

             }

             catch (Exception) { }

             return IntPtr.Zero;

         }

         #endregion

         //最小化到托盘

         private void Window_Min(object sender, RoutedEventArgs e)

         {

             //存储当前窗体句柄

             WPFNoSecond.SetIntPtr(new WindowInteropHelper(this).Handle.ToString());

         }