ActionScript 3.0概述畢業(yè)論文外文翻譯

1、英文原文actionscript 3.0 actionscript 3.0 is a powerful, object-oriented programming language that signifies an important step in the evolution of the capabilities of the flash player runtime. the motivation driving actionscript 3.0 is to create a language ideally suited for rapidly building rich intern

2、et applications, which have become an essential part of the web experience.earlier versions of actionscript offered the power and flexibility required for creating truly engaging online experiences. actionscript 3.0 now further advances the language, providing superb performance and ease of developm

3、ent to facilitate highly complex applications, large datasets, and object-oriented, reusable code bases. with actionscript 3.0, developers can achieve excellent productivity and performance with content and applications that target flash player.actionscript 3.0 is based on ecmascript, the internatio

4、nal standardized programming language for scripting. actionscript 3.0 is compliant with the ecmascript language specification, third edition . it also contains functionality based on ongoing work on ecmascript edition 4, occurring within the ecma standards body.actionscript is executed by the action

5、script virtual machine (avm) built into the flash player. avm1, the virtual machine used to execute legacy actionscript code, powers flash player today and makes possible a wide range of interactive media and rich internet applications.however, developers have started to push avm1 to its limits; the

6、ir project requirements now demand a major breakthrough. actionscript 3.0 introduces a new highly optimized actionscript virtual machine, avm2, which dramatically exceeds the performance possible with avm1. as a result, actionscript 3.0 code executes up to 10 times faster than legacy actionscript co

7、de.the new avm2 virtual machine is available in flash player 9, and will be the primary virtual machine for actionscript execution going forward. the older avm1 will continue to be supported by flash player for backwards compatibility with existing and legacy content.there are numerous products that

8、 generate content and applications targeted at the flash player runtime. often these products incorporate support for actionscript to add interactivity and behavior to their output. in the adobe product family, professional designers and developers might use actionscript within several tools and ser

9、verssuch as flash, flex, and flash media serverto create content and applications for flash player. the flex product family, including the new eclipse-based flex builder 2 ide, will be the first product line to access the new capabilities of actionscript 3.0.goals of actionscript 3.0we wanted action

10、script 3.0 to deliver an improved, consistent programming model; compliance with industry standards; and performance an order of magnitude greater than what we delivered in the past. although actionscript 3.0 represents a new programming model for the runtime, it is one that will be familiar to deve

11、lopers with a basic knowledge of object-oriented programming.actionscript 3.0 is designed to address the following goals: safety: the language supports type safety so developers can write unambiguous, easily maintainable code. simplicity: the language is intuitive enough for developers to be able to

12、 read and write programs without constantly consulting a reference manual. performance: the language enables developers to write complex programs that perform efficiently and responsively. compatibility: the language provides a short backward and forward compatibility path and a significant overlap

13、with industry standards. actionscript 3.0 is a dialect of ecmascript which formalizes the features of actionscript 2.0, adds the capabilities of ecmascript for xml (e4x), and unifies the language into a coherent whole.features of actionscript 3.0actionscript 3.0 consists of two parts: the core langu

14、age and the flash player api. the core language defines the basic building blocks of the programming language, such as statements, expressions, conditions, loops, and types. the flash player api is made up of classes that represent and provide access to flash playerspecific functionalityactionscript

15、 3.0 contains a host of powerful new features that can greatly speed the development process. regular expression support enables a variety of powerful operations on text. ecmascript for xml (e4x) transforms xml into a native data type, dramatically simplifying xml processing. the new display list ap

16、i makes working with visual objects far more straightforward and consistent. the standardized dom event model cements the way those objects talk and respond to each other at runtime. these are only a few of the many new capabilities of actionscript 3.0.language featuresactionscript 3.0 brings the co

17、re language aspects of actionscript 2.0 into compliance with the ecmascript standard and introduces some areas of new or enhanced functionality. all of these features are discussed in comprehensive detail in the actionscript 3.0 language reference, available in beta version on adobe labs.following i

18、s a high-level summary of the developer benefits and usage of some of the new features.runtime exceptionsin actionscript 2.0, many runtime errors would fail in a graceful but silent fashion. this ensured that flash player would not display some inexplicable dialog box, which javascript did in early

19、web browsers. on the other hand, this lack of error reporting made it more challenging to debug actionscript programs. actionscript 3.0 introduces a variety of runtime exceptions for common error conditions, improving the debugging experience and enabling applications that handle errors robustly. ru

20、ntime errors can provide stack traces annotated with source file and line number information, helping to pinpoint errors quickly.runtime typesin actionscript 2.0, type annotations were primarily an aid for developers; at runtime, all values were dynamically typed.in actionscript 3.0, type informatio

21、n is preserved at runtime and utilized for a number of purposes. flash player performs runtime type checking, improving the systems type safety. type information is also used to represent variables in native machine representations, improving performance and reducing memory usage.sealed classesactio

22、nscript 3.0 introduces the concept of a sealed class. a sealed class possesses only the fixed set of properties and methods that were defined at compile-time; additional properties and methods cannot be added. this makes stricter compile-time checking possible, resulting in more robust programs. it

23、also improves memory usage by not requiring an internal hash table for each object instance. dynamic classes are also possible using the dynamic keyword.method closuresevent handling is simplified in actionscript 3.0 thanks to method closures, which provide built-in event delegation. in actionscript

24、 2.0, a closure would not remember what object instance it was extracted from, leading to unexpected behavior when the closure was invoked. the mx.utils.delegate class was a popular workaround; to use it, you would write code as follows: mybutton.addeventlistener(click,delegate.create(this, somemeth

25、od); delegate.create(this, somemethod) this class is no longer needed because in actionscript 3.0, a method closure will be generated when somemethod is referenced. the method closure will automatically remember its original object instance. now, one can simply write:mybutton.addeventlistener(click,

26、 somemethod);附錄：譯文actionscript 3.0概述actionscript 3.0 演變成一門強大的面向對象的編程語言意味著flash平臺的重大變革。這種變化也意味著 actionscript 3.0 將創(chuàng)造性地將語言理想地迅速地建立出適應網絡的豐富應用程序, 成為豐富網絡應用(rich internet application)項目的本質部分。比較早期的actionscript版本就已經提供了這種要求為創(chuàng)造真實地參與在線體驗的力量和靈活性。actionscript 3.0 將促進和發(fā)展這種性能, 提供發(fā)展強大表現(xiàn)和舒適的先進的高度復雜應用, 結合大型數(shù)據(jù)庫以及可移值性的

27、面象對象的代碼。擁有 actionscript 3.0,開發(fā)者可能達到高效執(zhí)行效率和表現(xiàn)同一的平臺。 actionscript 3.0 基于ecmascript, ecmascript是所有編程語言的國際規(guī)范化的語言。actionscript 3.0 同樣遵從ecmascript語言規(guī)范。actionscript 由嵌入在flash player的actionscript虛擬機 (avm)執(zhí)行。avm1, 是執(zhí)行以前版本的actionscript的虛擬機, 今天變的更加強大的flash平臺使得可能創(chuàng)造出交互式媒體和豐富的網絡應用。然而, avm1卻在擠壓著開發(fā)者們的極限 他們的項目現(xiàn)在到了要求

28、它變革的時刻了。actionscript 3.0 帶來了一個更加高效的actionscript 執(zhí)行虛擬機avm2,它將徹底的脫胎換骨于avm1 。 它將意味著, actionscript 3.0執(zhí)行效率將比以前的actionscript執(zhí)行效率高出至少10倍。新的avm2 虛擬機將會嵌入于flash player8.5當中, 它將成為執(zhí)行actionscript的首先虛擬機。當然舊的avm1將繼續(xù)嵌入在flash player8.5當中以兼容以前的actionscript。 有眾多的產品把自身的展示和應用表現(xiàn)于flash player當中，這些產品的動畫也經常應用到actionscript

29、以增加互動和行為表現(xiàn)他們的產品。 在macromedia 產品家族, 專業(yè)設計師和也許使用 actionscript 在幾個產品當中, 譬如macromedia flash, flex,和flash media servers創(chuàng)造出內容和應用表現(xiàn)在flash player當中。在flex2 產品家族, 包括最新的基于eclipe的flex builder 2 ide,會是系列產品中第一個應用actionscript 3.0 的新體驗的產品。 actionscript 3.0的目標: 我們需要actionscript 3.0 提供一個先進的, 與編程模型一致的, 服從業(yè)界標準, 以及表現(xiàn)將數(shù)量級

30、大于我們過去的執(zhí)行效能。雖然actionscript 3.0 代表著flash平臺一個新的編程模型,它也將會是一個讓開發(fā)者熟悉的基礎的面對對象的編程語言。 actionscript3.0的出現(xiàn)將展現(xiàn)出如下目標： 安全 它支持一定的安全以使得能夠讓開發(fā)者寫出明白的, 容易的可維護的代碼。 樸素 - 這種語言的直觀程度使開發(fā)者能夠直接讀和寫項目,而不需要經常參考手冊 表現(xiàn) - 這種語言使開發(fā)者寫出高效率的和表現(xiàn)性強的復雜項目。 兼容性 - 這種語言拋棄不規(guī)范的語言標準以及提供向后兼容以及有意義的交替以符合業(yè)界標準。actionscript 3.0 是規(guī)范化了的actionscript 2.0, 增

31、 加了ecmascript 其中的xml應用(e4x) ,使得這 種語言融入ecmascript整體連為一貫。 actionscript 3.0的特征： actionscript 3.0 包括二部分: 核心語言和flash playerapi 。核心語言用于定義編程語言的結構, 譬如聲明, 表示, 條件, 循環(huán), 和類型 。flash player api是 由一系列精確定義flash player功能的類組成。actionscript 3.0 擁有盡可能的挖掘出計算機剩余性能的新特點。規(guī)則表示支持使操作性更加強大的xml。 ecmascript for xml (e4x) 使得xml 成為通用數(shù)據(jù)類型, 將大大地簡化xml 處理。新的display listapi將使虛擬對象更加的協(xié)調一致。 規(guī)范化的dom 事件模型使得那些對象的表示和響應結合的更加強勁。當然這些只是actionscript3.0許多新的體驗當中的一部分。actionscript3.0語言特點： actionscript 3.0 的出現(xiàn)是actionscript 2.0 的核心語言方面融入ecmascript 以遵守其標準和引入新的改進的一些功能區(qū)域的結合。所有這些特點在actionscript 3.0 語言參考中都有詳細的介紹和討論,可得到試用版正在