WPF程序只运行一个实例；
下面的代码还 尝试，如果窗体最小化的时候，让窗体还原
public partial class App : Application
{private static Semaphore singleInstanceWatcher;
private static bool createdNew; static App() { // Ensure other instances of this application are not running.singleInstanceWatcher = new Semaphore(
0, // Initial count.1, // Maximum count.
Assembly.GetExecutingAssembly().GetName().Name,
out createdNew); if (createdNew) { // This thread created the kernel object so no other instance // of this application must be running. //Application currApp = Application.Current; //currApp.StartupUri = new Uri("MainWindow.xaml", UriKind.RelativeOrAbsolute);MainWindow win = new MainWindow();
win.Show();
}
else { // This thread opened an existing kernel object with the same // string name; another instance of this app must be running now. // Gets a new System.Diagnostics.Process component and the // associates it with currently active process.Process current = Process.GetCurrentProcess();
// Enumerate through all the process resources on the share // local computer that the specified process name.foreach (Process process in
Process.GetProcessesByName(current.ProcessName))
{ if (process.Id != current.Id) { NativeMethods.SetForegroundWindow(process.MainWindowHandle);
NativeMethods.ShowWindow(process.MainWindowHandle, WindowShowStyle.Restore); break;}
}
// Terminate this process and gives the underlying operating // system the specified exit code.Environment.Exit(-2);
}
// 如果代码在Application_Startup中 如下
// private Semaphore singleInstanceWatcher;
// private bool createdNew;//private void Application_Startup(object sender, StartupEventArgs e)
//{ // singleInstanceWatcher = new Semaphore( // 0, // Initial count. // 1, // Maximum count. // Assembly.GetExecutingAssembly().GetName().Name, // out createdNew); // if (createdNew) // { // // This thread created the kernel object so no other instance // // of this application must be running. // Application currApp = Application.Current; // currApp.StartupUri = new Uri("MainWindow.xaml", UriKind.RelativeOrAbsolute); // } // else // { // //MessageBox.Show("系统已经运行"); // Process current = Process.GetCurrentProcess(); // foreach (Process process in // Process.GetProcessesByName(current.ProcessName)) // { // if (process.Id != current.Id) // { // NativeMethods.SetForegroundWindow( // process.MainWindowHandle); // NativeMethods.ShowWindow(process.MainWindowHandle, // WindowShowStyle.Restore); // break; // } // } // Environment.Exit(-2); // }}
}
internal enum WindowShowStyle : uint
{/// <summary>Hides the window and activates another window.</summary>
/// <remarks>See SW_HIDE</remarks>
Hide = 0,/// <summary>Activates and displays a window. If the window ..
/// or maximized, the system restores it to its original size and
/// position. An application should specify this flag when displaying
/// the window for the first time.</summary>
/// <remarks>See SW_SHOWNORMAL</remarks>
ShowNormal = 1,/// <summary>Activates the window and displays it ..</summary>
/// <remarks>See SW_SHOWMINIMIZED</remarks>
ShowMinimized = 2,/// <summary>Activates the window and displays it ..</summary>
/// <remarks>See SW_SHOWMAXIMIZED</remarks>
ShowMaximized = 3,/// <summary>Maximizes the specified window.</summary>
/// <remarks>See SW_MAXIMIZE</remarks>
Maximize = 3,/// <summary>Displays a window in its most recent size and position.
/// This value is similar to "ShowNormal", except the window is not
/// actived.</summary>
/// <remarks>See SW_SHOWNOACTIVATE</remarks>
ShowNormalNoActivate = 4,/// <summary>Activates the window and displays it in its current size
/// and position.</summary>
/// <remarks>See SW_SHOW</remarks>
Show = 5,/// <summary>Minimizes the specified window and activates the next
/// top-level window in the Z order.</summary>
/// <remarks>See SW_MINIMIZE</remarks>
Minimize = 6,/// <summary>Displays the window as a minimized window. This value is
/// similar to "ShowMinimized", except the window ..</summary>
/// <remarks>See SW_SHOWMINNOACTIVE</remarks>
ShowMinNoActivate = 7,/// <summary>Displays the window in its current size and position. This
/// value is similar to "Show", except the window ..</summary>
/// <remarks>See SW_SHOWNA</remarks>
ShowNoActivate = 8,/// <summary>Activates and displays the window. If the window is
/// minimized or maximized, the system restores it to its original size
/// and position. An application should specify this flag ..
/// a minimized window.</summary>
/// <remarks>See SW_RESTORE</remarks>
Restore = 9,/// <summary>Sets the show state based on the SW_ value specified ..
/// STARTUPINFO structure passed to the CreateProcess function by the
/// program that started the application.</summary>
/// <remarks>See SW_SHOWDEFAULT</remarks>
ShowDefault = 10,/// <summary>Windows 2000/XP: Minimizes a window, even if the thread
/// that owns the window is hung. This flag should only be used when
/// minimizing windows from a different thread.</summary>
/// <remarks>See SW_FORCEMINIMIZE</remarks>
ForceMinimized = 11}
static class NativeMethods
{ /// <summary>/// Brings the thread that created the specified window into the
/// foreground and activates the window. Keyboard input is directed
/// to the window, and various visual cues are changed for the user.
/// The system assigns a slightly higher priority to the thread that
/// created the foreground window than it does to other threads.
/// </summary>
/// <param name="hWnd">A handle to the window that should be
/// activated and brought to the foreground.
/// </param>
/// <returns>If the window was brought to the foreground, the
/// return value is nonzero. </returns>
[DllImport("user32.dll")]
internal static extern bool SetForegroundWindow(IntPtr hWnd);
/// <summary>Shows a Window</summary>
/// <remarks>/// <para>To perform certain special effects when showing or hiding a
/// window, use AnimateWindow.</para>
/// <para>The first time an application calls ShowWindow, it should use
/// the WinMain function's nCmdShow parameter as its nCmdShow ..
/// Subsequent calls to ShowWindow must use one of the values in the
/// given list, instead of the one specified by the WinMain function's
/// nCmdShow parameter.</para>
/// <para>As noted in the discussion of the nCmdShow parameter, the
/// nCmdShow value is ignored in the first call to ShowWindow if the
/// program that launched the application specifies startup information
/// in the structure. In this case, ShowWindow uses the information
/// specified in the STARTUPINFO structure to show the window. On
/// subsequent calls, the application must call ShowWindow with ..
/// set to SW_SHOWDEFAULT to use the startup information provided by ..
/// program that launched the application. This behavior is designed ..
/// the following situations: </para>
/// <list type="">/// <item>Applications create their main window by calling ..
/// with the WS_VISIBLE flag set. </item>
/// <item>Applications create their main window by calling ..
/// with the WS_VISIBLE flag cleared, and later call ShowWindow ..
/// SW_SHOW flag set to make it visible.</item>
/// </list></remarks>/// <param name="hWnd">Handle to the window.</param>
/// <param name="nCmdShow">Specifies how the window is to be shown.
/// This parameter is ignored the first time an application calls
/// ShowWindow, if the program that launched the application provides a
/// STARTUPINFO structure. Otherwise, the first time ShowWindow .. ,
/// the value should be the value obtained by the WinMain function ..
/// nCmdShow parameter. In subsequent calls, this parameter ..
/// the WindowShowStyle members.</param>
/// <returns>/// If the window was previously visible, the return value is nonzero.
/// If the window was previously hidden, the return value is zero.
/// </returns>
[DllImport("user32.dll")]
internal static extern bool ShowWindow(IntPtr hWnd,
WindowShowStyle nCmdShow);}