C#程序員經常用到的10個實用代碼片段
1 讀取操作系統和CLR的版本
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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系統中,輸出以下信息
Platform: Win32NT Service Pack: Version: 6.1.7600.0 VersionString: Microsoft Windows NT 6.1.7600.0 CLR Version: 4.0.21006.1
2 讀取CPU數量,內存容量
可以通過Windows Management Instrumentation (WMI)提供的接口讀取所需要的信息。
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; }
請添加對程序集System.Management的引用,確保代碼可以正確編譯。
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); }
3 讀取註冊表鍵值對
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)); } }
請添加命名空間Microsoft.Win32,以確保上面的代碼可以編譯。
4 啟動,停止Windows服務
這項API提供的實用功能常常用來管理應用程序中的服務,而不必到控制面板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卸載服務
if (args[0] == "/i") { ManagedInstallerClass.InstallHelper(new string[] { Assembly.GetExecutingAssembly().Location }); } else if (args[0] == "/u") { ManagedInstallerClass.InstallHelper(new string[] { "/u", Assembly.GetExecutingAssembly().Location }); }
如代碼所示,給應用程序傳入i或u參數,以表示是卸載或是安裝程序。
5 驗證程序是否有strong name (P/Invoke)
比如在程序中,為了驗證程序集是否有簽名,可調用如下方法
[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);
這個功能常用在軟件保護方法,可用來驗證簽名的組件。即使你的簽名被人去掉,或是所有程序集的簽名都被去除,只要程序中有這一項調用代碼,則可以停止程序運行。
6 響應系統配置項的變更
比如我們鎖定系統後,如果QQ沒有退出,則它會顯示了忙碌狀態。
請添加命名空間Microsoft.Win32,然後對註冊下面的事件。
. DisplaySettingsChanged (包含Changing) 顯示設置
. InstalledFontsChanged 字體變化
. PaletteChanged
. PowerModeChanged 電源狀態
. SessionEnded (用戶正在登出或是會話結束)
. SessionSwitch (變更當前用戶)
. TimeChanged 時間改變
. UserPreferenceChanged (用戶偏號 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許可文件之外的範圍,會導致ERP軟件不可用。
7 運用Windows7的新特性
Windows7系統引入一些新特性,比如打開文件對話框,狀態欄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();
用這樣的方法打開對話框,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,所以要調用這段代碼,還要檢查操作系統的版本要大於6,並且添加對程序集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
8 檢查程序對內存的消耗
用下面的方法,可以檢查.NET給程序分配的內存數量
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,它運行的結果如下所示
Before allocations: 651,064
After allocations: 40,690,080
使用下面的方法,可以檢查當前應用程序占用的內存
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 使用記秒表檢查程序運行時間
如果你擔憂某些代碼非常耗費時間,可以用StopWatch來檢查這段代碼消耗的時間,如下面的代碼所示
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序的運行時間,可以細化到每個方法,比如dotNetPerformance軟件。
以上面的代碼為例子,您需要直接修改源代碼,如果是用來測試程序,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); } }
借助於using語法,像下面的代碼所示,可以檢查一段代碼的運行時間,並打印在控制臺上。
using (new AutoStopwatch()) { Decimal total2 = 0; int limit2 = 1000000; for (int i = 0; i < limit2; ++i) { total2 = total2 + (Decimal)Math.Sqrt(i); } }
10 使用光標
當程序正在後臺運行保存或是冊除操作時,應當將光標狀態修改為忙碌。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,是為了預料到程序可能會拋出異常
using (new AutoWaitCursor(this)) { ... throw new Exception(); }
如代碼所示,即使拋出異常,光標也可以恢復到之間的狀態。
C#程序員經常用到的10個實用代碼片段