C#让程序只运行一次实例

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);
}
}