C# 程式開發中經常遇到的10條實用的程式碼

龐順龍發表於2019-05-11

OperatingSystem os = System.Environment.OSVersion;
Console.WriteLine(“Platform: {0}”, os.Platform);
Console.WriteLine(“Service Pack: {0}”, os.ServicePack);
Console.WriteLine(“Version: {0}”, os.Version);
Console.WriteLine(“VersionString: {0}”, os.VersionString);
Console.WriteLine(“CLR Version: {0}”, System.Environment.Version);

Platform: Win32NT 
Service Pack: 
Version: 6.1.7600.0 
VersionString: Microsoft Windows NT 6.1.7600.0 
CLR Version: 4.0.21006.1

可以通過Windows Management Instrumentation (WMI)提供的介面讀取所需要的資訊。
private static UInt32 CountPhysicalProcessors()
{
     ManagementObjectSearcher objects = new ManagementObjectSearcher(
        “SELECT * FROM Win32_ComputerSystem”);
     ManagementObjectCollection coll = objects.Get();
     foreach(ManagementObject obj in coll)
    {
        return (UInt32)obj[“NumberOfProcessors”];
    } 
    return 0;
}
private static UInt64 CountPhysicalMemory()
{
   ManagementObjectSearcher objects =new ManagementObjectSearcher(
      “SELECT * FROM Win32_PhysicalMemory”);
   ManagementObjectCollection coll = objects.Get();
   UInt64 total = 0;
   foreach (ManagementObject obj in coll)
   {
       total += (UInt64)obj[“Capacity”];
    }
    return total;
}
請新增對程式集System.Management的引用,確保程式碼可以正確編譯。
Console.WriteLine(“Machine: {0}”, Environment.MachineName);
Console.WriteLine(“# of processors (logical): {0}”, Environment.ProcessorCount);
Console.WriteLine(“# of processors (physical): {0}”  CountPhysicalProcessors());
Console.WriteLine(“RAM installed: {0:N0} bytes”,  CountPhysicalMemory());
Console.WriteLine(“Is OS 64-bit? {0}”,   Environment.Is64BitOperatingSystem);
Console.WriteLine(“Is process 64-bit? {0}”,  Environment.Is64BitProcess);
Console.WriteLine(“Little-endian: {0}”, BitConverter.IsLittleEndian);
foreach (Screen screen in  System.Windows.Forms.Screen.AllScreens)
{
     Console.WriteLine(“Screen {0}”, screen.DeviceName);
     Console.WriteLine(“\tPrimary {0}”, screen.Primary);
     Console.WriteLine(“\tBounds: {0}”, screen.Bounds);
     Console.WriteLine(“\tWorking Area: {0}”,screen.WorkingArea);
     Console.WriteLine(“\tBitsPerPixel: {0}”,screen.BitsPerPixel);
}
using (RegistryKey keyRun = Registry.LocalMachine.OpenSubKey(@”Software\Microsoft\Windows\CurrentVersion\Run”))
{
    foreach (string valueName in keyRun.GetValueNames())
    {
     Console.WriteLine(“Name: {0}\tValue: {1}”, valueName, keyRun.GetValue(valueName));
    }
}
請新增名稱空間Microsoft.Win32,以確保上面的程式碼可以編譯。
這項API提供的實用功能常常用來管理應用程式中的服務,而不必到控制皮膚的管理服務中進行操作。
ServiceController controller = new ServiceController(“e-M-POWER”);      
controller.Start();      
if (controller.CanPauseAndContinue)      
{      
    controller.Pause();      
    controller.Continue();      
}      
controller.Stop();      

//.net提供的API中,可以實現一句話安裝與解除安裝服務
 if (args[0] == "/i")
 {
       ManagedInstallerClass.InstallHelper(new string[] { Assembly.GetExecutingAssembly().Location });
 }
 else if (args[0] == "/u")
 {
       ManagedInstallerClass.InstallHelper(new string[] { "/u", Assembly.GetExecutingAssembly().Location });
 }
如程式碼所示,給應用程式傳入i或u引數,以表示是解除安裝或是安裝程式。
比如在程式中,為了驗證程式集是否有簽名,可呼叫如下方法
[DllImport("mscoree.dll", CharSet=CharSet.Unicode)]
static extern bool StrongNameSignatureVerificationEx(string wszFilePath, bool fForceVerification, ref bool  pfWasVerified);

bool notForced = false;
bool verified = StrongNameSignatureVerificationEx(assembly, false, ref notForced);
Console.WriteLine("Verified: {0}\nForced: {1}", verified, !notForced);
這個功能常用在軟體保護方法,可用來驗證簽名的元件。即使你的簽名被人去掉,或是所有程式集的簽名都被去除,只要程式中有這一項呼叫程式碼,則可以停止程式執行。

請新增名稱空間Microsoft.Win32,然後對註冊下面的事件。

. DisplaySettingsChanged (包含Changing)  顯示設定 
. InstalledFontsChanged  字型變化 
. PaletteChanged  
. PowerModeChanged 電源狀態 
. SessionEnded (使用者正在登出或是會話結束) 
. SessionSwitch (變更當前使用者) 
. TimeChanged 時間改變 
. UserPreferenceChanged (使用者偏號 包含Changing)

我們的ERP系統,會監測系統時間是否改變,如果將時間調整後ERP許可檔案之外的範圍,會導致ERP軟體不可用。

Windows7系統引入一些新特性,比如開啟檔案對話方塊,狀態列可顯示當前任務的進度。
Microsoft.WindowsAPICodePack.Dialogs.CommonOpenFileDialog ofd = new  Microsoft.WindowsAPICodePack.Dialogs.CommonOpenFileDialog();
ofd.AddToMostRecentlyUsedList = true;
ofd.IsFolderPicker = true;
ofd.AllowNonFileSystemItems = true;
ofd.ShowDialog();

用這樣的方法開啟對話方塊,與BCL自帶類庫中的OpenFileDialog功能更多一些。不過只限於Windows 7系統中,所以要呼叫這段程式碼,還要檢查作業系統的版本要大於6,並且新增對程式集Windows API Code Pack for Microsoft®.NET Framework的引用,請到這個地址下載http://code.msdn.microsoft.com/WindowsAPICodePack

用下面的方法,可以檢查.NET給程式分配的記憶體數量
long available = GC.GetTotalMemory(false);
Console.WriteLine(“Before allocations: {0:N0}”, available);
int allocSize = 40000000;
byte[] bigArray = new byte[allocSize];
available = GC.GetTotalMemory(false);
Console.WriteLine(“After allocations: {0:N0}”, available);


在我的系統中,它執行的結果如下所示

Before allocations: 651,064
After allocations: 40,690,080



Process proc = Process.GetCurrentProcess();
Console.WriteLine(“Process Info: “+Environment.NewLine+ 

 “Private Memory Size: {0:N0}”+Environment.NewLine +
“Virtual Memory Size: {1:N0}” + Environment.NewLine +

“Working Set Size: {2:N0}” + Environment.NewLine +
“Paged Memory Size: {3:N0}” + Environment.NewLine +
“Paged System Memory Size: {4:N0}” + Environment.NewLine +

  “Non-paged System Memory Size: {5:N0}” + Environment.NewLine,
proc.PrivateMemorySize64,   proc.VirtualMemorySize64,  proc.WorkingSet64,  proc.PagedMemorySize64, proc.PagedSystemMemorySize64,  proc.NonpagedSystemMemorySize64 );



如果你擔憂某些程式碼非常耗費時間,可以用StopWatch來檢查這段程式碼消耗的時間,如下面的程式碼所示


System.Diagnostics.Stopwatch timer = new System.Diagnostics.Stopwatch();
timer.Start();
Decimal total = 0;
int limit = 1000000;
for (int i = 0; i < limit; ++i)
{
      total = total + (Decimal)Math.Sqrt(i);
}
timer.Stop();
Console.WriteLine(“Sum of sqrts: {0}”,total);
Console.WriteLine(“Elapsed milliseconds: {0}”,
timer.ElapsedMilliseconds);
Console.WriteLine(“Elapsed time: {0}”, timer.Elapsed);


現在已經有專門的工具來檢測程式的執行時間,可以細化到每個方法,比如dotNetPerformance軟體。

以上面的程式碼為例子,您需要直接修改原始碼,如果是用來測試程式,則有些不方便。請參考下面的例子。


class AutoStopwatch : System.Diagnostics.Stopwatch, IDisposable
{
   public AutoStopwatch()
   { 
       Start();
   }
   public void Dispose()
   {
       Stop();
       Console.WriteLine(“Elapsed: {0}”, this.Elapsed);
   }
}


藉助於using語法,像下面的程式碼所示,可以檢查一段程式碼的執行時間,並列印在控制檯上。


using (new AutoStopwatch())
{
    Decimal total2 = 0;
    int limit2 = 1000000;
    for (int i = 0; i < limit2; ++i)
    {
       total2 = total2 + (Decimal)Math.Sqrt(i);
    }
}


當程式正在後臺執行儲存或是冊除操作時,應當將游標狀態修改為忙碌。可使用下面的技巧。


class AutoWaitCursor : IDisposable
{
    private Control _target;
    private Cursor _prevCursor = Cursors.Default;
    public AutoWaitCursor(Control control)
    {
       if (control == null)
       {
         throw new ArgumentNullException(“control”);
       }
       _target = control;
       _prevCursor = _target.Cursor;
       _target.Cursor = Cursors.WaitCursor;
    }
    public void Dispose()
    {
       _target.Cursor = _prevCursor;
    }
}


用法如下所示,這個寫法,是為了預料到程式可能會丟擲異常


using (new AutoWaitCursor(this))
{
    throw new Exception();
}


如程式碼所示,即使丟擲異常,游標也可以恢復到之間的狀態。


80iter碼農最後編輯於:5年前

內容均為作者獨立觀點,不代表八零IT人立場,如涉及侵權,請及時告知。

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