java的基礎(chǔ)外文翻譯

1、<p><b>　　外文原文</b></p><p>　　Java Fundamentals</p><p>　　The rise of the Internet and the World Wide Web have fundamentally reshaped computing. Only a few short years ago, the cybe

2、r landscape was dominated by stand-alone PCs. Today, nearly all PCs are connected to the Internet. The Internet, itself, was transformed—originally offering a convenient way to share files and information, today it is a

3、vast, distributed computing universe. These changes have been as rapid as they have been profound, and in their wake, they gave rise to a new way to program:</p><p>　　1.1 The Origins of Java</p><p

4、>　　Computer language innovation is driven forward by two factors: improvements in the art of programming and changes in the computing environment. Java is no exception. Building upon the rich legacy inherited from C a

5、nd C++, Java adds refinements and features that reflect the current state of the art in programming. Responding to the rise of the online environment, Java offers features that streamline programming for a highly distrib

6、uted architecture.</p><p>　　Java was conceived by James Gosling, Patrick Naughton, Chris Warth, Ed Frank, and Mike Sheridan at Sun Microsystems in 1991. This language was initially called “Oak” but was renam

7、ed “Java” in 1995. Somewhat surprisingly, the original impetus for Java was not the Internet! Instead, the primary motivation was the need for a platform-independent language that could be used to create software to be e

8、mbedded in various consumer electronic devices, such as toasters, microwave ovens, and remote control</p><p>　　Although it is possible to compile a C++ program for just about any type of CPU, to do so requir

9、es a full C++ compiler targeted for that CPU. The problem, however, is that compilers are expensive and time-consuming to create. In an attempt to find a better solution, Gosling Java Fundamentals and others worked on a

10、portable, cross-platform language that could produce code that would run on a variety of CPUs under differing environments. This effort ultimately led to the creation of Java.</p><p>　　About the time that th

11、e details of Java were being worked out, a second, and ultimately more important, factor emerged that would play a crucial role in the future of Java. This second force was, of course, the World Wide Web. Had the Web not

12、 taken shape at about the same time that Java was being implemented, Java might have remained a useful but obscure language for programming consumer electronics. However, with the emergence of the Web, Java was propelled

13、 to the forefront of computer language</p><p>　　Most programmers learn early in their careers that portable programs are as elusive as they are desirable. While the quest for a way to create efficient, porta

14、ble (platform-independent) programs is nearly as old as the discipline of programming itself, it had taken a back seat to other, more pressing problems. However, with the advent of the Internet and the Web, the old probl

15、em of portability returned with a vengeance. After all, the Internet consists of a diverse, distributed universe populate</p><p>　　By 1993 it became obvious to members of the Java design team that the proble

16、ms of portability frequently encountered when creating code for embedded controllers are also found when attempting to create code for the Internet. This realization caused the focus of Java to switch from consumer elect

17、ronics to Internet programming. So, while it was the desire for an architecture-neutral programming language that provided the initial spark, it was the Internet that ultimately led to Java’s large-scale </p><

18、p>　　How Java Relates to C and C++</p><p>　　Java is directly related to both C and C++. Java inherits its syntax from C. Its object model is adapted from C++. Java’s relationship with C and C++ is importan

19、t for several reasons. First, many programmers are familiar with the C/C++ syntax. This makes it easy for a C/C++ programmer to learn Java and, conversely, for a Java programmer to learn C/C++. </p><p>　　Sec

20、ond, Java’s designers did not “reinvent the wheel.” Instead, they further refined an already highly successful programming paradigm. The modern age of programming began with C. It moved to C++, and now to Java. By inheri

21、ting and building upon that rich heritage, Java provides a powerful, logically consistent programming environment that takes the best of the past and adds new features required by the online environment. Perhaps most imp

22、ortant, because of their similarities, C, C++, and Java d</p><p>　　One of the central design philosophies of both C and C++ is that the programmer is in charge! Java also inherits this philosophy. Except for

23、 those constraints imposed by the Internet environment, Java gives you, the programmer, full control. If you program well, your programs reflect it. If you program poorly, your programs reflect that, too. Put differently

24、, Java is not a language with training wheels. It is a language for professional programmers. </p><p>　　Java has one other attribute in common with C and C++: it was designed, tested, and refined by real, wo

25、rking programmers. It is a language grounded in the needs and experiences of the people who devised it. There is no better way to produce a top-flight professional programming language.</p><p>　　Because of t

26、he similarities between Java and C++, especially their support for objectoriented programming, it is tempting to think of Java as simply the “Internet version of C++.” However, to do so would be a mistake. Java has signi

27、ficant practical and philosophical differences. Although Java was influenced by C++, it is not an enhanced version of C++. For example, it is neither upwardly nor downwardly compatible with C++. Of course, the similariti

28、es with C++ are significant, and if you are a C+</p><p>　　How Java Relates to C#</p><p>　　Recently a new language called C# has come on the scene. Created by Microsoft to support its .NET Framew

29、ork, C# is closely reated to Java. In fact, many of C#’s features were directly adapted from Java. Both Java and C# share the same general C++-style syntax, support distributed programming, and utilize the same object mo

30、del. There are, of course, differences between Java and C#, but the overall “l(fā)ook and feel” of these languages is very similar. This means that if you already know C#, then lea</p><p>　　1.2 Java’s Contributi

31、on to the Internet</p><p>　　The Internet helped catapult Java to the forefront of programming, and Java, in turn, has had a profound effect on the Internet. The reason for this is quite simple: Java expands

32、the universe of objects that can move about freely in cyberspace. In a network, there are two very broad categories of objects that are transmitted between the server and your personal computer: passive information and d

33、ynamic, active programs. For example, when you read your e-mail, you are viewing passive data. Even w</p><p>　　As desirable as dynamic, networked programs are, they also present serious problems in the areas

34、 of security and portability. Prior to Java, cyberspace was effectively closed to half of the entities that now live there. As you will see, Java addresses those concerns and, in doing so, has defined a new form of progr

35、am: the applet.</p><p>　　Java Applets and Applications</p><p>　　Java can be used to create two types of programs: applications and applets. An application is a program that runs on your computer

36、, under the operating system of that computer. An application created by Java is more or less like one created using any other type of computer language, such as Visual Basic or C++. When used to create applications, Jav

37、a is not much different from any other computer language. Rather, it is Java’s ability to create applets that makes it important. An applet is an appl</p><p><b>　　Security</b></p><p>

38、;　　As you are almost certainly aware, every time you download a “normal” program, you are risking a viral infection. Prior to Java, most users did not download executable programs frequently, and those that did, scanned

39、them for viruses prior to execution. Even so, most users still worried about the possibility of infecting their systems with a virus or allowing a malicious program to run wild in their systems. (A malicious program migh

40、t gather private information, such as credit card numbers, bank</p><p>　　When using a Java-compatible web browser, it is possible to safely download Java applets without fear of viral infection. The way that

41、 Java achieves this is by confining a Java program to the Java execution environment and not allowing it access to other parts of the computer. (You will see how this is accomplished, shortly.) Frankly, the ability to do

42、wnload applets with confidence that no harm will be done to the client computer is the single most important aspect of Java.</p><p>　　Portability</p><p>　　As discussed earlier, many types of com

43、puters and operating systems are connected to the Internet. For programs to be dynamically downloaded to all of the various types of platforms, some means of generating portable executable code is needed. As you will soo

44、n see, the same mechanism that helps ensure security also helps create portability. Indeed, Java’s solution to these two problems is both elegant and efficient.</p><p><b>　　外文翻譯</b></p>&l

45、t;p><b>　　JAVA的基礎(chǔ)</b></p><p>　　互聯(lián)網(wǎng)和萬維網(wǎng)的崛起已經(jīng)從根本上重塑了計(jì)算。僅短短幾年前，網(wǎng)絡(luò)景觀的主導(dǎo)力量還是獨(dú)立的個(gè)人電腦。而今天，幾乎所有的電腦都連接到互聯(lián)網(wǎng)。互聯(lián)網(wǎng)本身也得到轉(zhuǎn)化，原本提供一個(gè)方便的途徑來共享文件和信息，而今天它是一個(gè)巨大的，分布式計(jì)算宇宙。因特網(wǎng)就像它本身的深度一樣迅速的變化，因?yàn)樵谝蛱鼐W(wǎng)之后，產(chǎn)生了一種新的語言進(jìn)行編程：Jav

46、a語言。</p><p>　　Java是互聯(lián)網(wǎng)的杰出的語言，但它不止于此。 Java具有革命性編程，改變了我們思考程序形式和功能的方式。今天要成為一名專業(yè)程序員今日意味著在Java的能力，它已成為這一重要計(jì)劃。在這本書的過程中，你將學(xué)習(xí)掌握它需要的技能。</p><p>　　本單元目的是向你介紹Java中，包括它的歷史，其設(shè)計(jì)理念，其最重要的特征數(shù)。到目前為止，有關(guān)學(xué)習(xí)一種編程語言最難的事

47、情是沒有孤立存在的元素。相反，語言的組成部分之間相互關(guān)聯(lián)。這在Java語言中尤為特別。事實(shí)上，很難討論Java的一個(gè)方面而不卷入Java的另外一些方面。為了幫助解決這個(gè)問題，這個(gè)模塊提供了一些Java特性，包括一個(gè)Java程序的一般形式簡(jiǎn)要概述，一些基本的控制結(jié)構(gòu)和運(yùn)算符。它不會(huì)進(jìn)入太多的細(xì)節(jié)，而是集中在任何Java程序都會(huì)有的一些共性。</p><p>　　1.1 Java的起源</p><

48、p>　　計(jì)算機(jī)語言創(chuàng)新是由兩個(gè)因素驅(qū)動(dòng)著：在編程藝術(shù)的改進(jìn)和計(jì)算環(huán)境的改變。 Java也沒有例外。Java從C和C++繼承傳統(tǒng)的基礎(chǔ)之上增加了豐富的改進(jìn)和功能，反映在編程的藝術(shù)現(xiàn)狀。為了響應(yīng)在線環(huán)境的增長(zhǎng)，Java提供了高度分布式架構(gòu)的流線編程。</p><p>　　Java是1991年由James Gosling，Patrick Naughton，Chris Warth，Ed Frank 和 Mike S

49、heridan在Sun公司構(gòu)想出來的。這種語言最初被稱為“Oak”，但在1995年改名為“Java”。奇怪的是，構(gòu)思Java的原始動(dòng)力竟然不是互聯(lián)網(wǎng)，相反，在主要的動(dòng)機(jī)是一個(gè)平臺(tái)無關(guān)的語言，可用于創(chuàng)建需要在各種消費(fèi)電子設(shè)備的嵌入式程序例如烤面包機(jī)，微波爐，遠(yuǎn)程控制。正如你可能猜到，許多不同類型的CPU都被作為控制器。麻煩的是，大多數(shù)計(jì)算機(jī)語言的目的是為特定目標(biāo)的編制。例如，C++就是。</p><p>　　雖然可

50、以編譯一個(gè)C++程序的幾乎所有類型的CPU，但是這樣需要一個(gè)完整的C++編譯器來對(duì)應(yīng)這個(gè)CPU。但問題是，創(chuàng)建編譯器昂貴而且費(fèi)時(shí)。James Gosling在試圖找到更好的解決辦法，他和他的同事們致力于一種便攜的，跨平臺(tái)的語言，它能產(chǎn)生在不同環(huán)境的cpu下都能運(yùn)行的代碼。這一努力最終導(dǎo)致了Java的產(chǎn)生。</p><p>　　正當(dāng)Java的細(xì)節(jié)正在擬定的時(shí)候，第二個(gè)因素，并最終顯得更重要的因素出現(xiàn)，并在在Java

51、的未來中起著重要的角色作用。這第二個(gè)推動(dòng)力量當(dāng)然是萬維網(wǎng)了。如果該網(wǎng)頁沒有和Java在同一時(shí)間出現(xiàn)并嶄露頭角，Java雖然仍然會(huì)是有用的編程語言但是不會(huì)作為為消費(fèi)電子編程的語言而著名。然而，隨著互聯(lián)網(wǎng)的出現(xiàn)，Java推動(dòng)對(duì)計(jì)算機(jī)語言設(shè)計(jì)的前沿，因?yàn)閃eb的出現(xiàn)，也要求便攜的編程方式。</p><p>　　大多數(shù)程序員在其職業(yè)生涯早期的學(xué)習(xí)中知道可移植程序是多么難以實(shí)現(xiàn)，因?yàn)樗鼈兪抢硐氲?。雖然尋求創(chuàng)造高效，可移植（

52、平臺(tái)無關(guān)）程序的方式幾乎和編程它自己一樣古老了，但是這必須解決諸多問題。然而，隨著互聯(lián)網(wǎng)和Web的發(fā)展，老問題的出現(xiàn)就像是報(bào)復(fù)一樣。畢竟，互聯(lián)網(wǎng)由一個(gè)多樣化的，分布式的計(jì)算機(jī)宇宙，包含了各種各樣的電腦，操作系統(tǒng)和CPU.曾經(jīng)非常棘手的問題現(xiàn)在不得不成為一個(gè)必須解決的問題了。</p><p>　　到了1993年，在可移植過程中經(jīng)常遇到的問題，對(duì)于Java的可移植性設(shè)計(jì)團(tuán)隊(duì)成員已經(jīng)能解決了。當(dāng)創(chuàng)造的嵌入式控制器的代碼

53、的同時(shí)，也在試圖創(chuàng)建互聯(lián)網(wǎng)的代碼。這一點(diǎn)認(rèn)識(shí)把Java的重點(diǎn)從消費(fèi)類電子的嵌入式開關(guān)過渡到互聯(lián)網(wǎng)編程了。因此，盡管Java設(shè)計(jì)為結(jié)構(gòu)中立的編程語言，提供最初的火花，但是這是最終導(dǎo)致Java在因特網(wǎng)大規(guī)模成功的原因。</p><p>　　Java與c和c++有何關(guān)聯(lián)</p><p>　　Java是直接關(guān)系到C和C + +。 Java的繼承了它從C語法的對(duì)象模型是從C + +改寫。 Java的

54、C和C + +的關(guān)系是很重要的幾個(gè)原因。第一，許多程序員用C / C + +語法熟悉。這就需要一個(gè)C / C + +程序員容易學(xué)習(xí)Java，相反，為Java程序員學(xué)習(xí)C / C + +的。</p><p>　　其次，Java的設(shè)計(jì)者并沒有“另起爐灶?！毕喾矗麄冞M(jìn)一步完善了已經(jīng)非常成功的編程范例。當(dāng)今時(shí)代的節(jié)目開始C.它移動(dòng)到C + +，現(xiàn)在到Java。通過繼承遺產(chǎn)，并呼吁富有建設(shè)，Java提供了一個(gè)強(qiáng)大的，在邏

55、輯上一致的編程環(huán)境，把過去的最好的，并增加了在線環(huán)境所需的新功能。也許最重要的，因?yàn)樗麄兊南嗨菩远x，C語言，C + +和Java的一個(gè)共同的，為專業(yè)程序員的概念框架。程序員不從一種語言時(shí)所面臨的切換到另一個(gè)重大分歧。</p><p>　　對(duì)C和C + +的核心設(shè)計(jì)理念之一是，程序員要負(fù)責(zé)！ Java也繼承這一理念。除通過互聯(lián)網(wǎng)環(huán)境施加的限制，讓你的Java，程序員，完全控制。如果你的方案好，它反映了你的方案。如

56、果方案不好，您的程序反映這一點(diǎn)。把不同的，Java是不是一個(gè)輪子的語言培訓(xùn)。這是一個(gè)專業(yè)的程序員的語言。</p><p>　　Java有一個(gè)共同的C和C + +其他屬性：它是設(shè)計(jì)，測(cè)試，以及真實(shí)的，精致的程序員工作。它是在需要和人民誰發(fā)明它的經(jīng)驗(yàn)為基礎(chǔ)的語言。有沒有更好的方法來生產(chǎn)一流的專業(yè)的編程語言。</p><p>　　由于Java與C + +的相似之處，特別是他們對(duì)面向?qū)ο缶幊讨С郑?/p>

57、這是很有誘惑力的爪哇看成簡(jiǎn)單的“C + +的網(wǎng)絡(luò)版?！比欢?，這樣做將是一個(gè)錯(cuò)誤。 Java具有重大現(xiàn)實(shí)和哲學(xué)的差異。雖然Java是由C + +的影響，它不是一個(gè)對(duì)C + +的增強(qiáng)版。例如，它既不向上也不向下兼容的C + +。當(dāng)然，用C + +的相似性是重要的，如果你是一個(gè)C + +程序員，你會(huì)覺得在權(quán)利與Java的家。另外一點(diǎn)：Java是不是要取代C + +。 Java的目的是要解決的問題的某些設(shè)置。 C + +的目的是為了解決不同的問

58、題。兩者將共存多年來。</p><p>　　Java與c#有何關(guān)聯(lián)</p><p>　　最近，一個(gè)新的語言稱為C＃對(duì)現(xiàn)場(chǎng)來。微軟支持其創(chuàng)建的。NET框架，C＃是Java的緊密reated。事實(shí)上，C＃的許多功能是直接改編自爪哇。 Java和C＃都共享相同的一般的C + +風(fēng)格的語法，支持分布式程序設(shè)計(jì)，并使用相同的對(duì)象模型。當(dāng)然有，Java和C之間的差異＃，但總的“外觀和感覺這些語言的”非

59、常相似。這意味著，如果你已經(jīng)知道C＃，那么學(xué)習(xí)Java將特別容易。反之，如果C＃是你的未來，那么你的Java知識(shí)能派上用場(chǎng)。由于在Java和C＃相似，人們可能會(huì)自然地問：“請(qǐng)問C＃中取代Java嗎？”答案是Java和C＃號(hào)是兩個(gè)不同類型的計(jì)算環(huán)境優(yōu)化。正如C + +和Java將合作很長(zhǎng)一段時(shí)間來存在，因此將C＃和Java。</p><p>　　1.2 Java對(duì)因特網(wǎng)的貢獻(xiàn)</p><p>

60、;　　互聯(lián)網(wǎng)幫助彈射Java來的節(jié)目的前列，和Java，反過來，已在互聯(lián)網(wǎng)上產(chǎn)生深遠(yuǎn)的影響。其原因是相當(dāng)簡(jiǎn)單：擴(kuò)大了的Java對(duì)象，可以在網(wǎng)絡(luò)空間中自由走動(dòng)宇宙的原因。在網(wǎng)絡(luò)中，有兩個(gè)非常廣泛的是在服務(wù)器之間和個(gè)人電腦：被動(dòng)的信息和動(dòng)態(tài)，積極傳播節(jié)目的各類文物。例如，當(dāng)你讀你的電子郵件，您正在查看的被動(dòng)數(shù)據(jù)。即使當(dāng)您下載一個(gè)程序，該程序的代碼還只是被動(dòng)的數(shù)據(jù)，直到你執(zhí)行它。然而，第二種類型的對(duì)象可以傳輸?shù)侥挠?jì)算機(jī)：一個(gè)動(dòng)態(tài)的，自動(dòng)執(zhí)行

61、程序。這種方案是在客戶端計(jì)算機(jī)活性劑，但它是由服務(wù)器發(fā)起的。例如，一個(gè)程序可能是由服務(wù)器提供正確顯示數(shù)據(jù)，這是發(fā)送。</p><p>　　作為理想的，動(dòng)態(tài)的，聯(lián)網(wǎng)方案，他們也出席在安全性和便攜性方面的嚴(yán)重問題。在此之前，到Java，網(wǎng)絡(luò)空間得到了有效封閉的實(shí)體，現(xiàn)在生活在那里的一半。正如你將看到，Java的解決這些問題，并在這樣做，已經(jīng)確定了新形式的節(jié)目：小程序。</p><p>　　Ja

62、va小程序和應(yīng)用</p><p>　　Java可以被用于創(chuàng)建兩種類型的程序：應(yīng)用程序和applet。應(yīng)用程序是一種程序，在您的計(jì)算機(jī)運(yùn)行在該計(jì)算機(jī)的操作系統(tǒng)。 Java是由或多或少像一個(gè)創(chuàng)建使用如Visual Basic或C + +計(jì)算機(jī)語言的任何其他類型的應(yīng)用軟件。當(dāng)用于創(chuàng)建應(yīng)用程序，Java沒有太大的任何其他計(jì)算機(jī)語言不同。相反，它是Java的創(chuàng)造能力，使小程序很重要。一個(gè)applet是一種應(yīng)用程序設(shè)計(jì)為在互

63、聯(lián)網(wǎng)上傳輸和Java的兼容的Web瀏覽器執(zhí)行。雖然任何計(jì)算機(jī)語言可以用來創(chuàng)建應(yīng)用程序，只有Java可以被用于創(chuàng)建一個(gè)applet。原因是，Java的小程序解決了兩個(gè)與有關(guān)的最棘手的問題：安全性和可移植性。在繼續(xù)之前，讓我們定義這兩個(gè)詞是什么意思相對(duì)于互聯(lián)網(wǎng)。</p><p><b>　　安全</b></p><p>　　如你幾乎可以肯定知道，每一次你下載一個(gè)“正?！钡?/p>

64、計(jì)劃，你是冒著一種病毒感染。在此之前爪哇，大多數(shù)用戶沒有下載可執(zhí)行程序頻繁，那些沒有，他們進(jìn)行了病毒掃描之前執(zhí)行。即便如此，大多數(shù)用戶仍然擔(dān)心的是感染了病毒或惡意程序，允許在其系統(tǒng)中運(yùn)行他們的系統(tǒng)野生的可能性。 （惡意程序可能會(huì)收集私人信息，如信用卡號(hào)碼，銀行賬戶余額和密碼通過搜索您的計(jì)算機(jī)的本地文件系統(tǒng)的內(nèi)容。）渣的答案提供了一個(gè)網(wǎng)絡(luò)應(yīng)用程序之間和你的電腦防火墻這些問題。</p><p>　　當(dāng)使用一個(gè)Java

65、兼容的網(wǎng)絡(luò)瀏覽器，它可以安全地下載不擔(dān)心感染病毒的Java小程序。爪哇的方式實(shí)現(xiàn)這一禁錮Java程序的Java執(zhí)行環(huán)境，不允許它訪問計(jì)算機(jī)的其他部分。 （你會(huì)看到這是如何完成，不久）。坦率地說，能夠下載滿懷信心地說，這樣做會(huì)不會(huì)傷害到客戶端計(jì)算機(jī)小程序是一個(gè)最重要的Java方面。</p><p><b>　　可移植性</b></p><p>　　在之前的討論中提到過，