C# Windows 桌面应用只运行一个实例

1） 根据“程序集的签名”获取已运行的实例

/// <summary>
/// 根据“程序集的签名”获取已运行的实例
///    .EXE 文件改名或路径改变，此方法可正常工作
/// </summary>
/// <param name="runningProcess">前一个实例的 Process</param>
/// <returns>是否有相同的实例在运行 ture/false</returns>
/// <remarks>需要对程序集进行签名。存在问题：速度稍慢。</remarks>
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;
}

 2） 根据“进程名称”获取已运行的实例

/// <summary>
/// 根据“进程名称”获取已运行的实例
/// </summary>
/// <param name="runningProcess">前一个实例的 Process</param>
/// <returns>是否有相同的实例在运行 ture/false</returns>
/// <remarks>存在问题：1)有可能有相同的进程名; 2)修改了文件名，此方法失效。</remarks>
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;
}

 3） 根据“进程名称和路径”获取已运行的实例

/// <summary>
/// 根据“进程名称和路径”获取已运行的实例
/// </summary>
/// <param name="runningProcess">前一个实例的 Process</param>
/// <returns>是否有相同的实例在运行 ture/false</returns>
/// <remarks>存在问题：修改了文件名或改变了文件路径，此方法失效。</remarks>
private static bool GetRunningProcessByProcessFullName(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.MainModule.FileName ==
               Assembly.GetExecutingAssembly().Location)
            {
                runningProcess = process;
                returnValue = true;
                break;
            }
        }
    }
    return returnValue;
}

 4） 根据“Mutex”判断是否有相同的实例在运行

/// <summary>
/// 根据“Mutex”判断是否有相同的实例在运行
/// </summary>
/// <param name="runningProcess">总是 null</param>
/// <returns>是否有相同的实例在运行 ture/false</returns>
/// <remarks>存在问题：不能返回前一个实例的 Process</remarks>
private static bool GetRunningProcessByMutex(out Process runningProcess)
{
    bool returnValue = false;
    runningProcess = null;

    bool isCreated;
    Mutex m = new Mutex(false, "OneInstance", out isCreated);
    if (!(isCreated))
    {
        MessageBox.Show("已经有相同的实例在运行。", "提示", 
             MessageBoxButtons.OK, MessageBoxIcon.Information);
    }
    returnValue = !isCreated;
    return returnValue;
}
#region 私有方法
/// <summary>
/// 设置指定进程的窗口为活动
/// </summary>
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
    {
        // 将窗口设为前台窗口
        SetForegroundWindow(process.MainWindowHandle);
    }
}

/// <summary>
/// 比较两个字节数组是否相等
/// </summary>
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;
}
#endregion

#region Windows API 声明
/// <summary>
/// 恢复一个最小化的程序，并将其激活
/// </summary>
/// <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);

/// <summary>
/// 窗口是否已最小化
/// </summary>
/// <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 IsIconic(IntPtr hWnd);

/// <summary>
/// 将窗口设为系统的前台窗口
/// </summary>
/// <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 int SetForegroundWindow(IntPtr hWnd);


/// <summary>
/// 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
/// </summary>
/// <param name="hWnd">窗口句柄</param>
/// <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);
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