.NET Framework类库(FCL)

框架类库或FCL在.NET Framework中提供了系统功能，因为它具有各种类，数据类型，接口等，以执行多种功能并构建不同类型的应用程序，例如桌面应用程序，Web应用程序，移动应用程序等框架类库与.NET框架的公共语言运行库(CLR)集成在一起，并且由所有.NET语言(例如C＃ ，F＃，Visual Basic .NET等)使用。

框架类库中的类别

框架类库的功能大致可分为三类，即Utility功能.NET编写，围绕OS的功能和框架的包装。这些类别没有严格定义，并且有许多类别可能适合多个类别。

框架类库中有关类别的详细信息如下：

• 实用程序功能： FCL中的实用程序功能包括各种集合类，例如列表，堆栈，队列，字典等，还包括用于更多种操作的类，例如用于正则表达式的Regex类。
• 围绕OS功能的包装： FCL中的某些功能是围绕底层Windows OS功能的包装。这些包括使用文件系统的类，处理网络功能的类，处理控制台应用程序的I / O的类，等等。
• 框架： FCL中提供了各种框架来开发某些应用程序。例如，ASP.NET用于开发Web应用程序，Windows Presentation Foundation(WPF)用于呈现Windows应用程序中的用户界面，依此类推。

框架类库中的命名空间

框架类库中的命名空间是一组可以由所有.NET框架语言使用的相关类和接口。 FCL中的某些名称空间及其描述如下：

Namespace	Description
Accessibility	The Accessibility namespace is a part of the managed wrapper for the COM accessibility interface.
Microsoft.Activities	The Microsoft.Activities namespace provides support for Windows Workflow Foundation applications.
Microsoft.CSharp	The Microsoft.CSharp namespace has support for compilation and code generation for the C# source code.
Microsoft.JScript	The Microsoft.JScript namespace has support for compilation and code generation for the JScript source code.
Microsoft.VisualBasic	The Microsoft.VisualBasic namespace has support for compilation and code generation for the VisualBasic source code.
System	The System namespace has base classes for definition of interfaces, data types, events, event handlers, attributes, processing exceptions etc.
System.Activities	The System.Activities namespace handles the creation and working with activities in the Window Workflow Foundation using various classes.
System.Collections	The System.Collections namespace has multiple standard, specialized, and generic collection objects that are defined using various types.
System.Configuration	The System.Configuration namespace handles configuration data using various types. This may include data in machine or application configuration files.
System.Data	The System.Data namespace accesses and manages data from various sources using different classes.
System.Drawing	The System.Drawing namespace handles GDI+ basic graphics functionality. Various child namespaces also handle vector graphics functionality, advanced imaging functionality, etc.
System.Globalization	The System.Globalization namespace handles language, country, calendars used, format patterns for dates, etc. using various classes.
System.IO	The System.IO namespaces support IO like data read/write into streams, data compression, communicate using named pipes etc. using various types.
System.Linq	The System.Linq namespace supports Language-Integrated Query (LINQ) using various types.
System.Media	The System.Media namespace handles sound files and accessing the sounds provided by the system using various classes.
System.Net	The System.Net namespace provides an interface for network protocols, cache policies for web resources, composing and sending e-mail etc. using various classes.
System.Reflection	The System.Reflection namespace gives a managed view of loaded methods, types, fields, etc. It can also create and invoke types dynamically.
System.Security	The System.Security namespace has the .NET security system and permissions. Child namespaces provide authentication, crytographic services etc.
System.Threading	The System.Threading namespace allows multithreaded programming using various types.
XamlGeneratedNamespace	The XamlGeneratedNamespace has compiler-generated types that are not used directly from the code.