1、ASP.NET Technique 1. Building ASP.NET Pages ASP.NET and the .NET Framework ASP.NET is part of Microsofts overall .NET framework, which contains a vast set of programming classes designed to satisfy any conceivable programming need. In the following two sections, you learn how ASP.NET fits within the
2、 .NET framework, and you learn about the languages you can use in your ASP.NET pages. The .NET Framework Class Library Imagine that you are Microsoft. Imagine that you have to support multiple programming languages such as Visual Basic, JScript, and C+. A great deal of the functionality of these pro
3、gramming languages overlaps. For example, for each language, you would have to include methods for accessing the file system, working with databases, and manipulating strings. Furthermore, these languages contain similar programming constructs. Every language, for example, can represent loops and co
4、nditionals. Even though the syntax of a conditional written in Visual Basic differs from the syntax of a conditional written in C+, the programming function is the same. Finally, most programming languages have similar variable data types. In most languages, you have some means of representing strin
5、gs and integers, for example. The maximum and minimum size of an integer might depend on the language, but the basic data type is the same. Maintaining all this functionality for multiple languages requires a lot of work. Why keep reinventing the wheel? Wouldnt it be easier to create all this functi
6、onality once and use it for every language? The .NET Framework Class Library does exactly that. It consists of a vast set of classes designed to satisfy any conceivable programming need. For example, the .NET framework contains classes for handling database access, working with the file system, mani
7、pulating text, and generating graphics. In addition, it contains more specialized classes for performing tasks such as working with regular expressions and handling network protocols. The .NET framework, furthermore, contains classes that represent all the basic variable data types such as strings,
8、integers, bytes, characters, and arrays. Most importantly, for purposes of this book, the .NET Framework Class Library contains classes for building ASP.NET pages. You need to understand, however, that you can access any of the .NET framework classes when you are building your ASP.NET pages. Underst
9、anding Namespaces As you might guess, the .NET framework is huge. It contains thousands of classes (over 3,400). Fortunately, the classes are not simply jumbled together. The classes of the .NET framework are organized into a hierarchy of namespaces. ASP Classic Note In previous versions of Active S
10、erver Pages, you had access to only five standard classes (the Response, Request, Session, Application, and Server objects). ASP.NET, in contrast, provides you with access to over 3,400 classes! A namespace is a logical grouping of classes. For example, all the classes that relate to working with th
11、e file system are gathered together into the System.IO namespace. The namespaces are organized into a hierarchy (a logical tree). At the root of the tree is the System namespace. This namespace contains all the classes for the base data types, such as strings and arrays. It also contains classes for
12、 working with random numbers and dates and times. You can uniquely identify any class in the .NET framework by using the full namespace of the class. For example, to uniquely refer to the class that represents a file system file (the File class), you would use the following: System.IO.File System.IO
13、 refers to the namespace, and File refers to the particular class. NOTE You can view all the namespaces of the standard classes in the .NET Framework Class Library by viewing the Reference Documentation for the .NET Framework. Standard ASP.NET Namespaces The classes contained in a select number of n
14、amespaces are available in your ASP.NET pages by default. (You must explicitly import other namespaces.) These default namespaces contain classes that you use most often in your ASP.NET applications: System Contains all the base data types and other useful classes such as those related to generating
15、 random numbers and working with dates and times. System.Collections Contains classes for working with standard collection types such as hash tables, and array lists. System.Collections.Specialized Contains classes that represent specialized collections such as linked lists and string collections. S
16、ystem.Configuration Contains classes for working with configuration files (Web.config files). System.Text Contains classes for encoding, decoding, and manipulating the contents of strings. System.Text.RegularExpressions Contains classes for performing regular expression match and replace operations.
17、 System.Web Contains the basic classes for working with the World Wide Web, including classes for representing browser requests and server responses. System.Web.Caching Contains classes used for caching the content of pages and classes for performing custom caching operations. System.Web.Security Co
18、ntains classes for implementing authentication and authorization such as Forms and Passport authentication. System.Web.SessionState Contains classes for implementing session state. System.Web.UI Contains the basic classes used in building the user interface of ASP.NET pages. System.Web.UI.HTMLContro
19、ls Contains the classes for the HTML controls. System.Web.UI.WebControls Contains the classes for the Web controls. .NET Framework-Compatible Languages For purposes of this book, you will write the application logic for your ASP.NET pages using Visual Basic as your programming language. It is the de
20、fault language for ASP.NET pages. Although you stick to Visual Basic in this book, you also need to understand that you can create ASP.NET pages by using any language that supports the .NET Common Language Runtime. Out of the box, this includes C#, JScript.NET, and the Managed Extensions to C+. NOTE
