如何确保只有一个应用程序实例在运行？

用System.Diagnostics 的Process类

[C#]
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;
}
[VB.NET]
Public Shared Function RunningInstance() As Process
Dim current As Process = Process.GetCurrentProcess()
Dim processes As Process() = Process.GetProcessesByName(current.ProcessName)
'Loop through the running processes in with the same name
Dim process As Process
For Each process In processes
'Ignore the current process
If process.Id <> current.Id Then
'Make sure that the process is running from the exe file.
If [Assembly].GetExecutingAssembly().Location.Replace("/", "/") = current.MainModule.FileName Then
'Return the other process instance.
Return process
End If
End If
Next process
'No other instance was found, return null.
Return Nothing
End Function 'RunningInstance