如何实现：如果一个程序已经运行，再次运行的时候，激活并显示程序的窗口
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);


Form1 myform = new Form1();

bool not_created;
Mutex m = new Mutex(true, "last ", out not_created);
if (not_created)
{

Application.Run(myform);
m.ReleaseMutex();
}
else
{

try
{

//用了n多种方法就是不成功
//myform.Show();
//myform.Activate();
//myform.Focus();
//myform.BringToFront();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}

}

}

另外，为了实现程序启动时隐藏（只在托盘显示图标），我加了
private void Form1_Shown(object sender, EventArgs e)
{
this.Hide();
}
跟这个有冲突吗？



[解决办法]
using System.Diagnostics;//用于使程序只运行一次
using System.Reflection;//用于使程序只运行一次
using System.Runtime.InteropServices; //用于使程序只运行一次
using System.IO;//用于使程序只运行一次

/// <summary>
/// 应用程序的主入口点。
/// </summary>
[STAThread]
static void Main()
{
//用于使程序只运行一次
Process instance=RunningInstance();
if( instance!= null )
{
//MessageBox.Show( "程序已在运行! " );
//确保窗口没有被最小化或最大化
ShowWindowAsync(instance.MainWindowHandle , 1);
//设置真实例程为foreground window
SetForegroundWindow (instance.MainWindowHandle);
return;
}
}

/// <summary>
/// 确保窗口没有被最小化或最大化 (用于使程序只运行一次)
/// </summary>
/// <param name= "hWnd "> 进程中主窗口的窗口句柄 </param>
/// <param name= "cmdShow "> 1还原窗口,2 窗口最小化,3 窗口最大化 </param>
/// <returns> </returns>
[DllImport( "User32.dll ")]
private static extern bool ShowWindowAsync( IntPtr hWnd, int cmdShow);

/// <summary>
/// 设置真实例程为foreground window (用于使程序只运行一次)
/// </summary>
/// <param name= "hWnd "> 进程中主窗口的窗口句柄 </param>
/// <returns> </returns>
[DllImport( "User32.dll ")]
private static extern bool SetForegroundWindow(IntPtr hWnd);

[解决办法]
/*
*How to prevent multiple application instances?
*See cSingletonApp class
*
*cSingletonApp.PreviousInstanceDetected detects previous instance of the application and returns
*its MainWindowHandle (if any)
*
*cSingletonApp.ShowPreviousInstance is more tricky. If the MainWindowHandle of the previous application
*instance is available, it activates the main window.
*What makes it tricky is that
*it works correctly even if some modal form is active or some dialog is running.
*
*Copyright ?2003 by Sergey A. Kryukov
*http://www.SAKryukov.org
*
*/
using System;
using System.Diagnostics;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using System.IO;

namespace SingletonApp {
/// <summary>
/// Singleton application class.
/// </summary>
public class cSingletonApp {

/// <summary>
/// Verifies if previous instance is detected.
/// </summary>
/// <param name= "handle "> </param>
/// <returns> </returns>
public static bool PreviousInstanceDetected(out IntPtr handle) {
handle = IntPtr.Zero;
Process currentProcess=Process.GetCurrentProcess();
string currentName = currentProcess.MainModule.FileName;
string shortCurrentName = Path.GetFileNameWithoutExtension(currentName);
Process[] processes = Process.GetProcessesByName(shortCurrentName);
foreach (Process aproc in processes) {
if (aproc.Id!=currentProcess.Id) {

if (aproc.MainModule.FileName==currentName) {
handle = aproc.MainWindowHandle;
return true;
} // if same full name
} // if not the same process
}
return false;
} // PreviousInstanceDetected()
/// <summary>
/// Shows previous instance.
/// </summary>
/// <param name= "handle "> </param>
public static void ShowPreviousInstance(IntPtr handle) {
if (handle==IntPtr.Zero) return;
IntPtr topWindow = GetLastActivePopup(handle);
if (topWindow==IntPtr.Zero) return;
if ( (IsWindowVisible(topWindow)) && (IsWindowEnabled(topWindow)) )
SetForegroundWindow(topWindow);
} // ShowPreviousInstance()
#region private: user32.dll imports
[DllImport( "user32.dll ")]
privatestatic extern IntPtr GetLastActivePopup(IntPtr handle);
[DllImport( "user32.dll ")]
privatestatic extern bool IsWindowVisible(IntPtr handle);
[DllImport( "user32.dll ")]
privatestatic extern bool IsWindowEnabled(IntPtr handle);
[DllImport( "user32.dll ")]
privatestatic extern void SetForegroundWindow(IntPtr handle);
#endregion // private
} // class cSingletonApp
} // namespace SingletonApp