C#让应用程序只运行一个实例的几种方法

/// <returns>已有实例运行返回true，否则为false</returns>
public bool IsRunningProcessByMutex()
{
     bool createNew;
     using (System.Threading.Mutex mutex = new System.Threading.Mutex(true, Application.ProductName, out createNew))
     {
          return !createNew;
     }
}

/// <param name="runningProcess">前一个实例的 Process</param> 
/// <returns>已有实例运行返回true，否则为false</returns>
private static bool GetRunningProcessByProcessName(out Process runningProcess)
{
    bool returnValue = false;
    runningProcess = null;

    Process current = Process.GetCurrentProcess();
    Process[] processes = Process.GetProcessesByName(current.ProcessName);
    foreach (Process process in processes)
    {
        if (process.Id != current.Id)
        {
            if (process.ProcessName == current.ProcessName)
            {
                runningProcess = process;
                returnValue = true;
                break;
            }
        }
    }
    return returnValue;
}

private static bool GetRunningProcessByProcessFullName(out Process runningProcess)
{
   //... 除进程变焦外，其它同方法2
            if (process.MainModule.FileName ==
               Assembly.GetExecutingAssembly().Location.Replace("/", "\\"))
} 

/// <param name="runningProcess">前一个实例的 Process</param> 
/// <returns>已有实例运行返回true，否则为false</returns>
private static bool GetRunningProcessByAssemblyName(out Process runningProcess)
{
    bool returnValue = false;
    runningProcess = null;

    AssemblyName currentAssemblyName =
             AssemblyName.GetAssemblyName(Assembly.GetExecutingAssembly().Location);
    AssemblyName processAssemblyName = new AssemblyName();

    Process current = Process.GetCurrentProcess();
    Process[] processes = Process.GetProcesses();
    foreach (Process process in processes)
    {
        // 排除一些其他进程，可以加快点速度。  
        if (process.Id != current.Id &&
            process.ProcessName != "System" &&
            process.ProcessName != "csrss" &&
            process.ProcessName != "svchost" &&
            process.ProcessName != "services" &&
            process.ProcessName != "smss" &&
            process.ProcessName != "winlogon" &&
            process.ProcessName != "explorer" &&
            process.ProcessName != "pds" &&
            process.ProcessName != "alg" &&
            process.ProcessName != "msdtc" &&
            process.ProcessName != "spoolsv" &&
            process.ProcessName != "lsass" &&
            process.ProcessName != "Idle" &&
            process.ProcessName != "iexplore" &&
            process.ProcessName != "sqlserver" &&
            process.ProcessName != "notepad" &&
            process.ProcessName != "360tray" &&
            process.ProcessName != "XDict"
            )
        {
            try
            {
                // 获取文件的程序集  
                processAssemblyName = AssemblyName.GetAssemblyName(process.MainModule.FileName);
            }
            catch (Exception)
            {
                processAssemblyName = null;
            }

            // 通过 GetPublicKey() 来获取程序集的公钥；需要对程序集签名，否则 GetPublicKey() 返回的是 Null。  
            if (processAssemblyName != null &&
                CompareBytes(currentAssemblyName.GetPublicKey(),
                                     processAssemblyName.GetPublicKey()))
            {
                runningProcess = process;
                returnValue = true;
                break;
            }
        }
    }
    return returnValue;
}

/// 比较两个字节数组是否相等  
private static bool CompareBytes(byte[] bytes1, byte[] bytes2)
{
    if (bytes1 == null || bytes2 == null)
        return false;

    if (bytes1.Length != bytes2.Length)
        return false;

    for (int i = 0; i < bytes1.Length; i++)
    {
        if (bytes1[i] != bytes2[i])
            return false;
    }
    return true;
}

/// 设置指定进程的窗口为活动  
private static void SetForegroundProcess(Process process)
{
    bool isIcon = IsIconic(process.MainWindowHandle);
    // 窗口是否已最小化  
    if (isIcon)
    {
        // 还原窗口  
        ShowWindowAsync(process.MainWindowHandle, SW_RESTORE);
    }
    else
    {
        //如果期望窗口显示为Normal模式，可先做如下设置
        //ShowWindowAsync(process.MainWindowHandle, SW_SHOWNORMAL);
        // 将窗口设为前台窗口  
        SetForegroundWindow(process.MainWindowHandle);
    }
}

/// 恢复一个最小化的程序，并将其激活  
/// <param name="hWnd">窗口句柄</param>  
/// <returns>非零表示成功，零表示失败</returns>  
[System.Runtime.InteropServices.DllImport("User32.dll")]
private static extern bool OpenIcon(IntPtr hWnd);

/// 窗口是否已最小化  
[System.Runtime.InteropServices.DllImport("User32.dll")]
private static extern bool IsIconic(IntPtr hWnd);

/// 将窗口设为系统的前台窗口  
[System.Runtime.InteropServices.DllImport("User32.dll")]
private static extern int SetForegroundWindow(IntPtr hWnd);

/// 与ShowWindow相似，只是这时的ShowWindow命令会投递到指定的窗口，然后进行异步处理。  
///     这样一来，就可控制从属于另一个进程的窗口的可视情况。  
///     同时无须担心另一个进程挂起的时候，自己的应用程序也会牵连其中返回值  
/// <param name="cmdShow">为窗口指定可视性方面的一个命令</param>  
/// <returns>如窗口之前是可见的，则返回TRUE（非零），否则返回FALSE（零）</returns>  
[System.Runtime.InteropServices.DllImport("User32.dll")]
private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);

//相关常量
private const int SW_HIDE = 0;                        //隐藏窗口，活动状态给令一个窗口   
private const int SW_SHOWNORMAL = 1;       //用原来的大小和位置显示一个窗口，同时令其进入活动状态   
private const int SW_SHOWMINIMIZED = 2;   //最小化窗口，并将其激活   
private const int SW_SHOWMAXIMIZED = 3;   //最大化窗口，并将其激活   
private const int SW_SHOWNOACTIVATE = 4; //用最近的大小和位置显示一个窗口，同时不改变活动窗口   
private const int SW_RESTORE = 9;                  //用原来的大小和位置显示一个窗口，同时令其进入活动状态   
private const int SW_SHOWDEFAULT = 10;     //根据默认 创建窗口时的样式 来显示  
#endregion  

        static void Main()
        {
            Process runningProcess = null;
            bool isRunning = GetRunningProcessByProcessFullName(out runningProcess);
            if (isRunning)
            {
                //已经有一个实例在运行
                SetForegroundProcess(runningProcess);
            }
            else
            {
                //没有实例在运行
                Application.Run(new Form1());
            }
        }