英文文献与翻译.docx

1、英文文献与翻译ASP.NET Technique1. Building ASP.NET PagesASP.NET and the .NET FrameworkASP.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

2、 the .NET framework, and you learn about the languages you can use in your ASP.NET pages.The .NET Framework Class LibraryImagine that you are Microsoft. Imagine that you have to support multiple programming languagessuch as Visual Basic, JScript, and C+. A great deal of the functionality of these pr

3、ogramming 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 string

5、s 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 function

6、ality 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, manipul

7、ating 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, inte

8、gers, 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.Understanding

9、 NamespacesAs 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 NoteIn previous versions of Active Server Pag

10、es, 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 the file sys

11、tem 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 working wi

12、th 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.FileSystem.IO refers to the

13、 namespace, and File refers to the particular class.NOTEYou 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 NamespacesThe classes contained in a select number of namespaces are avai

14、lable 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 random numbers and

15、 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.System.Configuration Co

16、ntains 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.System.Web Contains the

17、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 Contains classes for implemen

18、ting 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.HTMLControls Contains the classes for th

19、e HTML controls.System.Web.UI.WebControls Contains the classes for the Web controls.NET Framework-Compatible LanguagesFor 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 default language for ASP.NET pages.

20、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+.NOTEThe CD included with this book cont

21、ains C# versions of all the code samples.Dozens of other languages created by companies other than Microsoft have been developed to work with the .NET framework. Some examples of these other languages include Python, SmallTalk, Eiffel, and COBOL. This means that you could, if you really wanted to, w

22、rite ASP.NET pages using COBOL.Regardless of the language that you use to develop your ASP.NET pages, you need to understand that ASP.NET pages are compiled before they are executed. This means that ASP.NET pages can execute very quickly.The first time you request an ASP.NET page, the page is compil

23、ed into a .NET class, and the resulting class file is saved beneath a special directory on your server named Temporary ASP.NET Files. For each and every ASP.NET page, a corresponding class file appears in the Temporary ASP.NET Files directory. Whenever you request the same ASP.NET page in the future

24、, the corresponding class file is executed.When an ASP.NET page is compiled, it is not compiled directly into machine code. Instead, it is compiled into an intermediate-level language called Microsoft Intermediate Language (MSIL). All .NET-compatible languages are compiled into this intermediate lan

25、guage.An ASP.NET page isnt compiled into native machine code until it is actually requested by a browser. At that point, the class file contained in the Temporary ASP.NET Files directory is compiled with the .NET framework Just in Time (JIT) compiler and executed.The magical aspect of this whole pro

26、cess is that it happens automatically in the background. All you have to do is create a text file with the source code for your ASP.NET page, and the .NET framework handles all the hard work of converting it into compiled code for you.ASP CLASSIC NOTEWhat about VBScript? Before ASP.NET, VBScript was

27、 the most popular language for developing Active Server Pages.ASP.NET does not support VBScript, and this is good news. Visual Basic is a superset of VBScript, which means that Visual Basic has all the functionality of VBScript and more. So, you have a richer set of functions and statements with Vis

28、ual Basic.Furthermore, unlike VBScript, Visual Basic is a compiled language. This means that if you use Visual Basic to rewrite the same code that you wrote with VBScript, you can get better performance.If you have worked only with VBScript and not Visual Basic in the past, dont worry. Since VBScrip

29、t is so closely related to Visual Basic, youll find it easy to make the transition between the two languages.NOTEMicrosoft includes an interesting tool named the IL Disassembler (ILDASM) with the .NET framework. You can use this tool to view the disassembled code for any of the ASP.NET classes in th

30、e Temporary ASP.NET Files directory. It lists all the methods and properties of the class and enables you to view the intermediate-level code.This tool also works with all the ASP.NET controls discussed in this chapter. For example, you can use the IL Disassembler to view the intermediate-level code

31、 for the TextBox control (located in a file named System.Web.dll).Introducing ASP.NET ControlsASP.NET controls provide the dynamic and interactive portions of the user interface for your Web application. The controls render the content that the users of your Web site actually see and interact with.

32、For example, you can use controls to create HTML form elements, interactive calendars, and rotating banner advertisements.ASP.NET controls coexist peacefully with HTML content. Typically, you create the static areas of your Web pages with normal HTML content and create the dynamic or interactive portions with ASP.NET controls.The best way to understand how ASP.NET controls work in an HTML page is to look at a simple Web Forms Page.Adding Application Logic to an ASP.NET PageThe second building block of an ASP.NET page is the application logic, whic