关于c#中的 Application，Environment，AppDomain 等类

[电脑不需要休息吗？]

小弟对C#学习不够深入，不太理解这几个类Application，Environment，AppDomain；
请高手介绍一下这几个类，
小弟感激不尽！

恭祝：
新春快乐！
牛年更牛！

[king19840811]

http://msdn.microsoft.com/zh-cn/library/system.windows.forms.application.aspx
MSDN最好的手册了。。

[lovehongyun]

Environment 类
提供有关当前环境和平台的信息以及操作它们的方法。无法继承此类。

// Sample for Environment class summary
using System;
using System.Collections;

class Sample 
{
    public static void Main() 
    {
    String str;
    String nl = Environment.NewLine;
//
    Console.WriteLine();
    Console.WriteLine("-- Environment members --");

//  Invoke this sample with an arbitrary set of command line arguments.
    Console.WriteLine("CommandLine: {0}", Environment.CommandLine);

    String[] arguments = Environment.GetCommandLineArgs();
    Console.WriteLine("GetCommandLineArgs: {0}", String.Join(", ", arguments));

//  <-- Keep this information secure! -->
    Console.WriteLine("CurrentDirectory: {0}", Environment.CurrentDirectory);

    Console.WriteLine("ExitCode: {0}", Environment.ExitCode);

    Console.WriteLine("HasShutdownStarted: {0}", Environment.HasShutdownStarted);

//  <-- Keep this information secure! -->
    Console.WriteLine("MachineName: {0}", Environment.MachineName);

    Console.WriteLine("NewLine: {0}  first line{0}  second line{0}  third line",
                          Environment.NewLine);

    Console.WriteLine("OSVersion: {0}", Environment.OSVersion.ToString());

    Console.WriteLine("StackTrace: '{0}'", Environment.StackTrace);

//  <-- Keep this information secure! -->
    Console.WriteLine("SystemDirectory: {0}", Environment.SystemDirectory);

    Console.WriteLine("TickCount: {0}", Environment.TickCount);

//  <-- Keep this information secure! -->
    Console.WriteLine("UserDomainName: {0}", Environment.UserDomainName);

    Console.WriteLine("UserInteractive: {0}", Environment.UserInteractive);

//  <-- Keep this information secure! -->
    Console.WriteLine("UserName: {0}", Environment.UserName);

    Console.WriteLine("Version: {0}", Environment.Version.ToString());

    Console.WriteLine("WorkingSet: {0}", Environment.WorkingSet);

//  No example for Exit(exitCode) because doing so would terminate this example.

//  <-- Keep this information secure! -->
    String query = "My system drive is %SystemDrive% and my system root is %SystemRoot%";
    str = Environment.ExpandEnvironmentVariables(query);
    Console.WriteLine("ExpandEnvironmentVariables: {0}  {1}", nl, str);

    Console.WriteLine("GetEnvironmentVariable: {0}  My temporary directory is {1}.", nl,
                           Environment.GetEnvironmentVariable("TEMP"));

    Console.WriteLine("GetEnvironmentVariables: ");
    IDictionary	environmentVariables = Environment.GetEnvironmentVariables();
    foreach (DictionaryEntry de in environmentVariables)
        {
        Console.WriteLine("  {0} = {1}", de.Key, de.Value);
        }

    Console.WriteLine("GetFolderPath: {0}", 
                 Environment.GetFolderPath(Environment.SpecialFolder.System));

    String[] drives = Environment.GetLogicalDrives();
    Console.WriteLine("GetLogicalDrives: {0}", String.Join(", ", drives));
    }
}
/*
This example produces results similar to the following:
(Any result that is lengthy or reveals information that should remain 
secure has been omitted and marked "!---OMITTED---!".)

C:\>env0 ARBITRARY TEXT

-- Environment members --
CommandLine: env0 ARBITRARY TEXT
GetCommandLineArgs: env0, ARBITRARY, TEXT
CurrentDirectory: C:\Documents and Settings\!---OMITTED---!
ExitCode: 0
HasShutdownStarted: False
MachineName: !---OMITTED---!
NewLine:
  first line
  second line
  third line
OSVersion: Microsoft Windows NT 5.1.2600.0
StackTrace: '   at System.Environment.GetStackTrace(Exception e)
   at System.Environment.GetStackTrace(Exception e)
   at System.Environment.get_StackTrace()
   at Sample.Main()'
SystemDirectory: C:\WINNT\System32
TickCount: 17995355
UserDomainName: !---OMITTED---!
UserInteractive: True
UserName: !---OMITTED---!
Version: !---OMITTED---!
WorkingSet: 5038080
ExpandEnvironmentVariables:
  My system drive is C: and my system root is C:\WINNT
GetEnvironmentVariable:
  My temporary directory is C:\DOCUME~1\!---OMITTED---!\LOCALS~1\Temp.
GetEnvironmentVariables: 
  !---OMITTED---!
GetFolderPath: C:\WINNT\System32
GetLogicalDrives: A:\, C:\, D:\

*/

[lovehongyun]

AppDomain 类
表示应用程序域，它是一个应用程序在其中执行的独立环境。无法继承此类。

应用程序域（由 AppDomain 对象表示）为执行托管代码提供隔离、卸载和安全边界。

使用应用程序域隔离可能终止进程的任务。如果正在执行任务的 AppDomain 的状态变得不稳定，则可以卸载 AppDomain，但不会影响进程。当进程必须不重新启动而长时间运行时，这一点很重要。还可使用应用程序域隔离不应共享数据的任务。

如果程序集被加载到默认应用程序域中，则当进程运行时将无法从内存中卸载该程序集。但是，如果打开另一个应用程序域来加载和执行程序集，则卸载该应用程序域时也会同时卸载程序集。使用此技术最小化长时间运行的进程的工作集，这些进程偶尔会使用大型 DLL。

多个应用程序域可以在一个进程中运行；但是，在应用程序域和线程之间没有一对一的关联。多个线程可以属于一个应用程序域，尽管给定的线程并不局限于一个应用程序域，但在任何给定时间，线程都在一个应用程序域中执行。

应用程序域通过使用 CreateDomain 方法来创建。AppDomain 实例用于加载和执行程序集 (Assembly)。当不再使用 AppDomain 时，可以将它卸载。

AppDomain 类实现一组事件，这些事件使应用程序可以在加载程序集、要卸载应用程序域或引发未处理的异常时进行响应。

有关使用应用程序域的更多信息，请参见 应用程序域。

此类实现 MarshalByRefObject、_AppDomain 和 IEvidenceFactory 接口。

在任何情况下都不应创建 AppDomain 对象的可远程控制的包装。这样做可发布对该 AppDomain 的远程引用，将诸如 CreateInstance 方法向远程访问公开，并有效损坏该 AppDomain 的代码访问安全性。连接到远程 AppDomain 的恶意客户端可以获得对 AppDomain 本身可访问的所有资源的访问权。您不应为任何以下类型创建可远程控制的包装：扩展 MarshalByRefObject 的类型和实现恶意客户端可用来绕过安全系统的方法的类型。

using System;
using System.Reflection;
using System.Threading;

class Module1
{
    public static void Main()
    {
        // Get and display the friendly name of the default AppDomain.
        string callingDomainName = Thread.GetDomain().FriendlyName;
        Console.WriteLine(callingDomainName);

        // Get and display the full name of the EXE assembly.
        string exeAssembly = Assembly.GetEntryAssembly().FullName;
        Console.WriteLine(exeAssembly);

        // Construct and initialize settings for a second AppDomain.
        AppDomainSetup ads = new AppDomainSetup();
        ads.ApplicationBase = 
            "file:///" + System.Environment.CurrentDirectory;
        ads.DisallowBindingRedirects = false;
        ads.DisallowCodeDownload = true;
        ads.ConfigurationFile = 
            AppDomain.CurrentDomain.SetupInformation.ConfigurationFile;

        // Create the second AppDomain.
        AppDomain ad2 = AppDomain.CreateDomain("AD #2", null, ads);

        // Create an instance of MarshalbyRefType in the second AppDomain. 
        // A proxy to the object is returned.
        MarshalByRefType mbrt = 
            (MarshalByRefType) ad2.CreateInstanceAndUnwrap(
                exeAssembly, 
                typeof(MarshalByRefType).FullName
            );

        // Call a method on the object via the proxy, passing the 
        // default AppDomain's friendly name in as a parameter.
        mbrt.SomeMethod(callingDomainName);

        // Unload the second AppDomain. This deletes its object and 
        // invalidates the proxy object.
        AppDomain.Unload(ad2);
        try
        {
            // Call the method again. Note that this time it fails 
            // because the second AppDomain was unloaded.
            mbrt.SomeMethod(callingDomainName);
            Console.WriteLine("Sucessful call.");
        }
        catch(AppDomainUnloadedException)
        {
            Console.WriteLine("Failed call; this is expected.");
        }
    }
}

// Because this class is derived from MarshalByRefObject, a proxy 
// to a MarshalByRefType object can be returned across an AppDomain 
// boundary.
public class MarshalByRefType : MarshalByRefObject
{
    //  Call this method via a proxy.
    public void SomeMethod(string callingDomainName)
    {
        // Get this AppDomain's settings and display some of them.
        AppDomainSetup ads = AppDomain.CurrentDomain.SetupInformation;
        Console.WriteLine("AppName={0}, AppBase={1}, ConfigFile={2}", 
            ads.ApplicationName, 
            ads.ApplicationBase, 
            ads.ConfigurationFile
        );

        // Display the name of the calling AppDomain and the name 
        // of the second domain.
        // NOTE: The application's thread has transitioned between 
        // AppDomains.
        Console.WriteLine("Calling from '{0}' to '{1}'.", 
            callingDomainName, 
            Thread.GetDomain().FriendlyName
        );
    }
}

/* This code produces output similar to the following: 

AppDomainX.exe
AppDomainX, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null
AppName=, AppBase=C:\AppDomain\bin, ConfigFile=C:\AppDomain\bin\AppDomainX.exe.config
Calling from 'AppDomainX.exe' to 'AD #2'.
Failed call; this is expected.
 */

[homejiji]

学习了，以前一直不太明白

[lianhui1122]

收藏下

[电脑不需要休息吗？]

谢谢各位！

[sunwukong]

在程序中用它做什么？

[小范f-li.cn]

mark!~