标签：

一 判断是否有相同的实例已经运行 1 根据“Mutex”判断是否有相同的实例在运行

/// <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;
     }
}

特点：不能返回前一个（已经运行的）实例的 Process

2 根据进“程名称”判断是否有相同的实例在运行，如果已运行，则返回已运行的实例

/// <param>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;
}

特点：1)不同程序有可能有相同的进程名; 
         2)如果运行了一个实例后修改文件名再运行另外一个实例，此方法失效。

3 根据“进程名称和路径”判断是否有相同的实例在运行，如果已运行，则返回已运行的实例

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("http://www.mamicode.com/", "\\"))
} 

特点：修改了文件名或改变了文件路径，此方法失效。

4 根据“程序集的签名”判断是否有相同的实例在运行，如果已运行，则返回已运行的实例

/// <param>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;
}