用如下方法可以保证应用程序只运行一个实例。

添加引用

using

 System.Reflection;

using

 System.Runtime.InteropServices;

using

 System.Diagnostics;

调用DLL文件

[DllImport(

"

User32.dll

"

)]

private

 

static

 

extern

 

bool

 ShowWindowAsync(IntPtr hWnd, 

int

 cmdShow);

[DllImport(

"

User32.dll

"

)]

private

 

static

 

extern

 

bool

 SetForegroundWindow(IntPtr hWnd);

private

 

const

 

int

 WS_SHOWNORMAL 

=

 

1

;

添加如下两个函数

public

 

static

 Process RunningInstance()

{

    Process current 

=

 Process.GetCurrentProcess();

    Process[] processes 

=

 Process.GetProcessesByName(current.ProcessName);

    

//

Loop   through   the   running   processes   in   with   the   same   name

    

foreach

 (Process process 

in

 processes)

    {

        

//

Ignore   the   current   process

        

if

 (process.Id 

!=

 current.Id)

        {

            

//

Make   sure   that   the   process   is   running   from   the   exe   file.

            

if

 (Assembly.GetExecutingAssembly().Location.Replace(

"

/

"

, 

"

\\

"

) 

==

                current.MainModule.FileName)

            {

                

//

Return   the   other   process   instance.

                

return

 process;

            }

        }

    }

    

//

No   other   instance   was   found,   return   null.

    

return

 

null

;

}

public

 

static

 

void

 HandleRunningInstance(Process instance)

{

    

//

Make   sure   the   window   is   not   minimized   or   maximized

    ShowWindowAsync(instance.MainWindowHandle, WS_SHOWNORMAL);

    

//

Set   the   real   intance   to   foreground   window

    SetForegroundWindow(instance.MainWindowHandle);

}

在MAIN中添加如下代码

public static void Main()

{

    Process instance 

=

 RunningInstance()

;

    if (instance 

==

 null)

    {

        Application.Run(new Form1())

;

    }

    else

    {

        HandleRunningInstance(instance)

;

    }

}