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1、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 the .

2、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 languages such as Visual Basic, JScript, and C+.A great deal of the functionality of these programm

3、ing 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 conditio

4、nals. 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 strings and

5、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 functionality

6、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, manipulating

7、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, integers,

8、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 Names

9、pacesAs 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 Pages, yo

10、u 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 system ar

11、e 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 with ran

12、dom 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 names

13、pace, 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 available

14、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 worki

15、ng 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 Contains

16、 classes for workingwithconfiguration files (Web.config files).System.Text Contains classes for encoding, decoding,andmanipulating the contents of strings.System.Text.RegularExpressions Containsclasses for performingregular expression match and replace operations.System.Web Contains the basic classe

17、s for working with the WorldWide 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 implementing authenti

18、cation 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 the HTML contro

19、ls.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. Although you

20、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 contains C# versi

21、ons 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, write ASP.NET

22、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 compiled into a .NE

23、T 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 TemporaryASP.NET Files directory. Whenever you request the same ASP.NET page in the future, the correspo

24、nding class file is executed.into an intermediate-levelWhen an ASP.NET page is compiled, it is not compiled directly intomachine code. Instead, it is compiled language.language called MicrosoftIntermediateLanguage (MSIL).All .NET-compatiblelanguages are compiledinto this intermediateAn ASP.NET page

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

26、 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 the most popular langu

27、age 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 Visual Basic.Furthermore,

28、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 VBScript is so closely related

29、 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 the Temporary ASP.NET Fil

30、es 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 for the TextBox contro

31、l (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. For example, you can u

32、se 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 con

33、trols.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, which is the actual programming code in the page. You add application lo

34、gic to a page to handle both control and page events.If a user clicks a Button control within an HTML form, for example, the Button control raises an event (the Click event). Typically, you want to add code to the page that does something in response to this event. For example, when someone clicks t

35、he Button control, you might want to save the form data to a file or database.Controls are not the only things that can raise events. An ASP.NET page itself raises several events every time it is requested. For example, whenever you request a page, the pagesLoad event is triggered. Youcan add applic

36、ation logic to the page that executes whenever the Load event occurs.2. Building Forms with Web Server ControlsBuilding Smart FormsYou use several of the basic Web controls to represent standard HTML form elements such as radio buttons, text boxes, and list boxes.You can use these controls in your A

37、SP.NET pages to create the user interface for your Web application. The following sections provide detailed overviews and programming samples for each of these Web controls.Controlling Page NavigationIn the following sections, you learn how to control how a user moves from one ASP.NET page to anothe

38、r. First, you learn how to submit an HTML form to another page and retrieve form information. Next, you learn how to use the Redirect() method to automatically transfer a user to a new page. Finally, you learn how to link pages together with the HyperLink control.Applying Formatting to ControlsIn th

39、e following sections, you learn how to make more attractive Web forms. First, you look at an overview of the formatting properties common to all Web controls; they are the formatting properties of the base control class. Next, you learn how to apply Cascading Style Sheet styles and classes to Web co

40、ntrols.3. Performing Form Validation with Validation ControlsUsing Client-side ValidationTraditionally, Web developers have faced a tough choice when adding form validation logic to their pages. You can add form validation routines to your server-side code, or you can add the validation routines to

41、your client-side code.The advantage of writing validation logic in client-side code is that you can provide instant feedback to your users. For example, if a user neglects to enter a value in a required form field, you can instantly display an error message without requiring a roundtrip back to the

42、server.People really like client-side validation. It looks great and creates a better overall user experience. The problem, however, is that it does not work with all browsers. Not all browsers support JavaScript, and different versions of browsers support different versions of JavaScript, so client

43、-side validation is never guaranteed to work.For this reason, in the past, many developers decided to add all their form validation logic exclusively to server-side code. Because server-side code functions correctly with any browser, this course of action was safer.Fortunately, the Validation contro

44、ls discussed in this chapter do not force you to make this difficult choice. The Validation controls automatically generate both client-side and server-side code. If a browser is capable of supporting JavaScript, client-side validation scripts are automatically sent to the browser. If a browser is i

45、ncapable of supporting JavaScript, the validation routines are automatically implemented in server-side code.You should be warned, however, that client-side validation works only with Microsoft Internet Explorer version 4.0 and higher. In particular, the client-side scripts discussed in this chapter

46、 do not work with any version of Netscape Navigator.Requiring Fields: The RequiredFieldValidator ControlYou use RequiredFieldValidator in a Web form to check whether a control has a value. Typically, you use this control with a TextBox control. However, nothing is wrong with using RequiredFieldValid

47、ator with other input controls such as RadioButtonList.Validating Expressions: The RegularExpressionValidator ControlYou can use RegularExpressionValidator to match the value entered into a form field to a regular expression. You can use this control to check whether a user has entered, for example,

48、 a valid e-mail address,telephone number, or username or password. Samples of how to use a regular expression to perform all these validation tasks are provided in the following sections.Comparing Values: The CompareValidator ControlThe CompareValidator control performs comparisons between the data

49、entered into a form field and another value. The other value can be a fixed value, such as a particular number, or a value entered into another control.Summarizing Errors: The ValidationSummary ControlImagine that you have a form with 50 form fields. If you use only the Validation controls discussed

50、 in the previous sections of this chapter to display errors, seeing an error message on the page might be difficult. For example, you might have to scroll down to the 48th form field to find the error message.Fortunately, Microsoft includes a ValidationSummary control with the Validation controls. Y

51、ou can use this control to summarize all the errors at the top of a page, or wherever else you want.4. Advanced Control ProgrammingWorking with View StateBy default, almost all ASP.NET controls retain the values of their properties between form posts. For example, if you assign text to a Label contr

52、ol and submit the form, when the page is rendered again, the contents of the Label control are preserved.The magic of view state is that it does not depend on any special server or browser properties. In particular, it does not depend on cookies, session variables, or application variables. View sta

53、te is implemented with a hidden form field called VIEWSTATE that is automatically created in every Web Forms Page.When used wisely, view state can have a dramatic and positive effect on the performance of your Web site. For example, if you display database data in a control that has view state enabl

54、ed, you do not have to return to the database each time the page is posted back to the server. You can automatically preserve the data within the pages view state between form posts.Displaying and Hiding ContentImagine that you are creating a form with an optional section. For example, imagine that

55、you are creating an online tax form, and you want to display or hide a section that contains questions that apply only to married tax filers.Or, imagine that you want to add an additional help button to the tax form. You might want to hide or display detailed instructions for completing form questio

56、ns depending on a users preferences.Finally, imagine that you want to break the tax form into multiple pages so that a person views only one part of the tax form at a time.In the following sections, you learn about the properties that you can use to hide and display controls in a form. You learn how

57、 to use the Visible and Enabled properties with individual controls and groups of controls to hide and display page content.Using the Visible and Enabled PropertiesEvery control, including both HTML and Web controls, has a Visible property that determines whether the control is rendered. When a cont

58、rols Visible property has the value False, the control is not displayed on the page; the control is not processed for either pre-rendering or rendering.Web controls (but not every HTML control) have an additional property named Enabled. When Enabled has the value False and you are using Internet Exp

59、lorer version 4.0 or higher, the control appears ghosted and no longer functions. When used with other browsers, such as Netscape Navigator, the control might not appear ghosted, but it does not function.Disabling View StateIn certain circumstances, you might want to disable view state for an indivi

60、dual control or for an ASP.NET page as a whole. For example, you might have a control that contains a lot of data (imagine a RadioButtonList control with 1,000 options). You might not want to load the data into the hidden _VIEWSTATE form field if you are worried that the form data would significantl

61、y slow down the rendering of the page.Using Rich ControlsIn the following sections, you learn how to use three of the more feature-rich controls in the ASP.NET framework. You learn how to use the Calendar control to display interactive calendars, the AdRotator control to display rotating banner adve

62、rtisements, and the HTMLInputFile control to accept file uploads.McDonald, Zipuzita theAdvanced ASP.NET 3.5 Programming (2nd Edition)-可编辑修改 -可编辑修改 -ASP.NET 技术1. 构建 ASP.NET 页面ASP.NET 和 ASP.NET 结构ASP.NET 是微软 .NET framework 整体的一部分 , 它包含一组大量的编程 用的类，满足各种编程需要。 在下列的二个部分中 , 你如何学会 ASP.NET 很 适合的放在 .NET framew

63、ork, 和学会能在你的 ASP.NET 页面中使用语言。.NET 类库假想你是微软。 假想你必须支持大量的编程语言 -比如 Visual Basic 、 C# 和 C+. 这些编程语言的很多功能具有重叠性。 举例来说，对于每一种语言， 你必须包括存取文件系统、与数据库协同工作和操作字符串的方法。此外，这些语言包含相似的编程构造。 每种语言 ,举例来说，都能够使用循 环语句和条件语句。 即使用 Visual Basic 写的条件语句的语法不与 用 C+ 写的不一样 ,程序的功能也是相同的。最后，大多数的编程语言有相似的数据变量类型。 以大多数的语言，你有 设定字符串类型和整型数据类型的方法。举

64、例来说， 整型数据最大值和最小值 可能依赖语言的种类，但是基本的数据类型是相同的。对于多种语言来说维持这一功能需要很大的工作量。 为什么继续再创轮子 ? 对所有的语言创建这种功能一次， 然后把这个功能用在每一种语言中岂不是更容.NET类库不完全是那样。它含有大量的满足编程需要的类。举例来说，.NET 类库包含处理数据库访问的类和文件协同工作，操作文本和生成图像。 除此之 外，它包含更多特殊的类用在正则表达式和处理 Web 协议。.NET framework ，此外包含支持所有的基本变量数据类型的类，比如：字 符串、整型、字节型、字符型和数组。最重要地,写这一本书的目的，.NET类库包含构建的

65、ASP.NET页面的类。 然而你需要了解当你构建.NET页面的时候能够访问.NET framework 的任意理解命名空间正如你猜测的 , .NET framework 是庞大的。 它包含数以千计的类 （超过3,400） 。幸运地，类不是简单的堆在一起。 .NET framework 的类被组织成有层 次结构的命名空间。ASP Classic Note在先前的ASP中，你仅仅能够访问五个标准类。相比之下ASP.NET提供超 过 3,400 个类!一个命名空间包含一组逻辑的类。 举例来说， 涉及到与文件系统协同工作的 类就集合在 System.IO 命名空间中。命名空间被组织成一个层次结构 （一棵逻辑树 ） 。 树根就是 SYSTEM 命名空 间。 这个命名空间包含基本的数据类型的所有的类 ,例如：字符串、数组，还包 含提供随机数字和日期的类。你通过完整的类的命名空间能唯一识别任何的类在 .NET framework 中的位 置。 举例来说 ,指定找到一个 the File clas