毕业论文英文文献及翻译.doc

英文原文ASP.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 .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 programming 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 conditionals. 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 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 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 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, 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 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 Note In previous versions of Active Server 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 the 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 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 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 NamespacesThe classes contained in a select number of namespaces 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 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. System.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. 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 Contains 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.HTMLControls Contains the classes for the 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 (and the most popular programming language in the world). 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# (pronounced See Sharp), JScript.NET (the .NET version of JavaScript), and the Managed Extensions to C+.NOTEThe CD included with this book contains 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, write 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 compiled 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, 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 language. 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 process 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 NOTE What about VBScript? Before ASP.NET, VBScript was 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 Visual 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 VBScript is so closely related to Visual Basic, youll find it easy to make the transition between the two languages.NOTE Microsoft 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 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 for the TextBox control (located in a file named System.Web.dll).中文翻译ASP.NET 和 .NET FrameworkASP.NET是微软.NET框架总体战略的一部分。它包含了一组满足各种可以想象到的需求的类。在之后的两个部分，你将会学到ASP.NET是怎样融合到.NET框架中去的，而且你将会学到可以在ASP.NET页面中使用到的语言。.NET框架类库 假设你就是微软，假设你必须支持多语言编程，例如VB,JS,C+。这些语言的很多函数都重复了，比如对于每种语言，你都必须包含一些访问文件系统，与数据库打交道，以及处理字符串的函数。而且这些语言都包含了相似的变成结构。每种语言都有循环和条件语句。虽然条件语句的语法有些出入，但是功能还是一样的。最后，很多变成语言都有相似的变量类型定义。在很多语言中，你都可以表达出字符串类型和整型。整型数的最大和最小值则由语言本身决定，但基本的表量类型还是相同的。维护所有这些语言的函数会很费事。干吗要不断的重复历史的车轮？如果只对函数建立一次而后对每种语言都使用是否会更爽些？而.net框架类库正是如此，它包含了一组为满足变成需要而设计的类。举例来说，.net框架包含了处理数据库访问的一组类。同时还有文件系统处理类以及视图产生类。而且，他包含了更多的较为细化的用来处理正则表达式和网络协议的类。 更重要的是，.net框架还将所有一些基础变量都表示了出来，例如字符串类型，整型，字符型和数组。最重要的也是本书的主要目的，.net框架类库包含了用来建立页面的类。你需要明白的是，你可以在建立自己的页面的时候访问任何一个.net框架中的类。搞懂命名空间正如你所想的，.net框架很庞大。他包含了数以千计的类。还好的是，这些类不是杂乱的拼在一起的。.net框架中的这些类是按照命名空间的各个层次组织在一起的。在asp过去的版本中，你仅仅可以访问五个标准类。想必来说，则为你提供了多达3400个类。命名空间就是对类进行逻辑上的划分。比如，所有和文件系统相关的类都被放入system.io的命名空间中。同时，命名空间也被组织为一个逻辑上的分层。在这个逻辑分层的最根部是system命名空间。这个命名空间包含了所有与基础数据类型相关的类，比如字符串和数组。同时他还包含了处理随机数和日期时间的类。通过使用类的全称，你可以唯一的定位任何一个类。比如定为一个表示文件系统的file类，你可以使用以下的命名：System.IO.File System.IO表示命名空间，而File表示这个特殊的类。注意如果想要浏览在.net框架类库中的所有的关于标准类的命名空间，你可以通过浏览参考文档。标准命名空间 部分命名空间中包含的一些类是默认可以使用的，但有些命名空间则必须明确的引用进来。这些默认的命名空间包含了你最常使用的一些类。 System-包含了所有基础类型和其他一些有用的类，例如涉及到产生随机数以及和时间和日期相关的类。 System.Collections-包含了一些例如hash表和数组列表这些标准集合类型的类。 System.Collections.Specialized-包含一些表示比较特殊的集合，比如链表和字符串集合。 System.Configuration-包含了处理配置文件的一些类。 System.Text-包含了一些涉及到编码，解码以及处理字符串内容的类。 System.Text.RegularExpressions-包含了进行正则表达式匹配及替换的操作的类。 System.Web-包含了处理网络方面的一些基本的类，包括表示浏览器请求及服务端应答的类。 System.Web.Caching-包含了一些用来缓存页面和类的内容以用来做一些常规的缓存操作的类。 System.Web.Security-包含了一些执行鉴定和授权的类，例如Forms和Passport鉴定。 System.Web.SessionState-包含了处理session的状态的一些类。 System.Web.UI-包含了用来建立ASP.NET页面的用户接口的基本类。 System.Web.UI.HTMLControls包含类的HTML控件。 System.Web.UI.WebControls包含类的Web控件。.NET框架兼容的语言 这本书的目的，是使你会使用Visual Basic作为您的编程语言来实现ASP.NET页。Visual Basic是ASP.NET网页的默认语言（并且是世界上最流行的编程语言） 。虽然在这本书中您坚持使用Visual Basic，但您还需要了解得是，您可以使用任何支持. NET通用语言运行库的语言创建ASP.NET页。这些语言包括C （发音为sharp） ， JScript.NET （. NET版本的JavaScript ）和扩展C + + 。注意 随本书携带的CD包含C 所有版本的代码示例。 除微软公司之外还有许多其他公司也已经开发出数十种可以在. NET Framework平台上进行开发的语言 。例如Python ， SmallTalk ，Eiffel，和COBOL等等。这就意味着，如果你想用COBOL来编写ASP.NET页，那么你就可以使用COBOL语言来编写 。 无论您使用何种语言来建立你的ASP.NET页，你必须明白 ASP.NET页首先汇编，然后才执行。这意味着， ASP.NET页可以非常快的执行。 您第一次请求ASP.NET页，该页首汇编成. NET类，汇编产生的类文件将保存在你的服务器上的一个特殊的目录命名为Temporary ASP.NET Files文件中。每个ASP.NET页，与之相应的类文件会出现在Temporary ASP.NET目录中。在未来当你请求同一ASP.NET页面时，相应的类文件就会被执行。 当ASP.NET页面编译时，它不是直接将其编译成机器代码。相反，是将它编译成称为微软中间语言（ MSIL ）的中间语言,所有与. NET兼容的语言都将被编译成中间语言。 一个ASP.NET的网页在它没有被浏览器请求之前是不会编译成本地机器代码的。在这一点上， 在Temporary ASP.NET Files文件目录中包含的类文件只有在编译和执行的时候被. NET Framework编译。 在整个过程中最神奇的方面就是这一切都是在后台自动完成的。所有你需要做的就是为你的ASP.NET页源代码创建一个文本文件，并且.NET framework将会处理所有困难的工作，并为你把它转换成汇编代码。 经典的ASP需要注意的问题在ASP.NET之前，VBScript语言是制作动态服务器网页最热门的语言。 ASP.NET不支持脚本，这是确实是一个好消息。 Visual Basic是VBScript的超集 ，这意味着Visual Basic不仅有VBScript的所有功能而且有更多的功能。所以，你可以用Visual Basic实现更丰富多样的功能。 此外，不像VBScript ， Visual Basic是一种汇编语言。这就意味着，如果你使用Visual Basic重写你用VBScript编写的实现相同功能的代码，你可以得到更好的性能。 请不要担心，如果你在过去的工作中只用VBScript而不是Visual Basic。由于VBScript与Visual Basic有着十分紧密的关系中，你会发现实现两种语言的过渡是十分容易的。 注意 Microsoft包含一个与. NET Framework相关的名为the IL Disassembler (ILDASM)的有趣工具，。你可以使用此工具，查看拆卸任何在Temporary ASP.NET文件目录中的ASP.NET类的代码。它列出了所有的方法和属性允许你查看中级代码。 此工具也可以作用于所有在本章中讨论ASP.NET控件。例如，您可以使用的IL Disassembler，查看中级代码为TextBox的控件（位于一个名为System.Web.dll 的文件中）。