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C#程序员经常用到的10个实用代码片段

  1 读取操作系统和CLR的版本


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);

  在我的Windows 7系统中,输出以下信息

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

  2 读取CPU数量,内存容量

  可以通过Windows Management Instrumentation (WMI)提供的接口读取所需要的信息。


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;
}

  请添加对程序集System.Management的引用,确保代码可以正确编译。


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);
}

  3 读取注册表键值对


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));
    }
}

  请添加命名空间Microsoft.Win32,以确保上面的代码可以编译。

  4 启动,停止Windows服务

  这项API提供的实用功能常常用来管理应用程序中的服务,而不必到控制面板的管理服务中进行操作。


ServiceController controller = new ServiceController(“e-M-POWER”);      
controller.Start();      
if (controller.CanPauseAndContinue)      
{      
    controller.Pause();      
    controller.Continue();      
}      
controller.Stop();      

  .net提供的API中,可以实现一句话安装与卸载服务


 if (args[0] == "/i")
 {
       ManagedInstallerClass.InstallHelper(new string[] { Assembly.GetExecutingAssembly().Location });
 }
 else if (args[0] == "/u")
 {
   ManagedInstallerClass.InstallHelper(new string[] { "/u", Assembly.GetExecutingAssembly().Location });
 }

  如代码所示,给应用程序传入i或u参数,以表示是卸载或是安装程序。

  5 验证程序是否有strong name (P/Invoke)

  比如在程序中,为了验证程序集是否有签名,可调用如下方法


[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);

  这个功能常用在软件保护方法,可用来验证签名的组件。即使你的签名被人去掉,或是所有程序集的签名都被去除,只要程序中有这一项调用代码,则可以停止程序运行。

  6 响应系统配置项的变更

  比如我们锁定系统后,如果QQ没有退出,则它会显示了忙碌状态。

  请添加命名空间Microsoft.Win32,然后对注册下面的事件。

  . DisplaySettingsChanged (包含Changing)  显示设置
  . InstalledFontsChanged  字体变化
  . PaletteChanged 
  . PowerModeChanged 电源状态
  . SessionEnded (用户正在登出或是会话结束)
  . SessionSwitch (变更当前用户)
  . TimeChanged 时间改变
  . UserPreferenceChanged (用户偏号 包含Changing)

  我们的ERP系统,会监测系统时间是否改变,如果将时间调整后ERP许可文件之外的范围,会导致ERP软件不可用。

  7 运用Windows7的新特性

  Windows7系统引入一些新特性,比如打开文件对话框,状态栏可显示当前任务的进度。


Microsoft.WindowsAPICodePack.Dialogs.CommonOpenFileDialog ofd = new  Microsoft.WindowsAPICodePack.Dialogs.CommonOpenFileDialog();
ofd.AddToMostRecentlyUsedList = true;
ofd.IsFolderPicker = true;
ofd.AllowNonFileSystemItems = true;
ofd.ShowDialog();

  用这样的方法打开对话框,与BCL自带类库中的OpenFileDialog功能更多一些。不过只限于Windows 7系统中,所以要调用这段代码,还要检查操作系统的版本要大于6,并且添加对程序集Windows API Code Pack for Microsoft®.NET Framework的引用,请到这个地址下载 http://code.msdn.microsoft.com/WindowsAPICodePack

  8 检查程序对内存的消耗

  用下面的方法,可以检查.NET给程序分配的内存数量


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);

  在我的系统中,它运行的结果如下所示


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

  使用下面的方法,可以检查当前应用程序占用的内存


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 );

  9 使用记秒表检查程序运行时间

  如果你担忧某些代码非常耗费时间,可以用StopWatch来检查这段代码消耗的时间,如下面的代码所示


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);

  现在已经有专门的工具来检测程序的运行时间,可以细化到每个方法,比如dotNetPerformance软件。

  以上面的代码为例子,您需要直接修改源代码,如果是用来测试程序,则有些不方便。请参考下面的例子。


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

  借助于using语法,像下面的代码所示,可以检查一段代码的运行时间,并打印在控制台上。


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

  10 使用光标

  当程序正在后台运行保存或是册除操作时,应当将光标状态修改为忙碌。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,这个写法,是为了预料到程序可能会抛出异常


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

  如代码所示,即使抛出异常,光标也可以恢复到之间的状态。

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