【正文】 ow long will it be before you can roll your own? If you buy it, you will have to climb the learning curve— and how long is that going to take? There is no right answer here, but most observers would agree that frameworks such as Struts provide a significant return on investment pared to starting from scratch, especially for larger projects. Other types of frameworks: The idea of a framework applies not only to applications but to application ponentsas well. Throughout this article, we introduce other types of frameworks that you can use with Struts. These include the Lucene search engine, the Scaffold toolkit, the Struts validator, and the Tiles tag library. Like application frameworks, these tools provide semiplete versions of a subsystem that can be specialized to provide a custom ponent. Some frameworks have been linked to a proprietary development environment. This is not the case with Struts or any of the other frameworks shown in this book. You can use any development environment with Struts: Visual Age for Java, JBuilder, Eclipse, Emacs, and Textpad are all popular choices among Struts developers. If you can use it with Java, you can use it with Struts. Enabling technologies: Applications developed with Struts are based on a number of enabling ponents are not specific to Struts and underlie every Java web application. A reason that developers use frameworks like Struts is to hide the nasty details behind acronyms like HTTP, CGI, and JSP. As a Struts developer, you don’t need to be an alphabet soup guru, but a working knowledge of these base technologies can help you devise creative solutions to tricky problems. Hypertext Transfer Protocol (HTTP): When mediating talks between nations, diplomats often follow a formal protocol. Diplomatic protocols are designed to avoid misunderstandings and to keep negotiations from breaking down. In a similar vein, when puters need to talk, they also follow a formal protocol. The protocol defines how data is transmitted and how to decode it once it arrives. Web applications use the Hypertext Transfer Protocol (HTTP) to move data between the browser running on your puter and the application running on the server. Many server applications municate using protocols other than HTTP. Some of these maintain an ongoing connection between the puters. The application server knows exactly who is connected at all times and can tell when a connection is dropped. Because they know 畢業(yè)設(shè)計(jì)外文翻譯 16 the state of each connection and the identity of each person using it, these are known as stateful protocols. By contrast, HTTP is known as a stateless protocol. An HTTP server will accept any request from any client and will always provide some type of response, even if the response is just to say no. Without the overhead of negotiating and retaining a connection, stateless protocols can handle a large volume of requ。t understand servlet programming. 3. Some tasks are better acplished by servlets than by JSP. JSP is good at generating pages that consist of large sections of fairly well structured HTML or other character data. Servlets are better for generating binary data, building pages with highly variable structure, and performing tasks (such as redirection) that involve little or no output. 4. Some tasks are better acplished by a bination of servlets and JSP than by either servlets or JSP alone. Versus JavaScript JavaScript, which is pletely distinct from the Java programming language, is normally used to dynamically generate HTML on the client, building parts of the Web page as the browser loads the document. This is a useful capability and does not normally overlap with the capabilities of JSP (which runs only on the server). JSP pages still include SCRIPT tags for JavaScript, just as normal HTML pages do. In fact, JSP can even be used to dynamically generate the JavaScript that will be sent to the client. So, JavaScript is not a peting technology。 you aren39。它提供一個(gè)控制器servlet 來(lái)處理導(dǎo)航流和一些特殊類來(lái)幫助數(shù)據(jù)訪問(wèn)。一個(gè)頁(yè)面的動(dòng)態(tài)數(shù)據(jù)可以使用一個(gè) JavaBean來(lái)傳遞，并且 JSP 標(biāo)記可以隨后使用 bean的屬性來(lái)定制頁(yè)面的輸出。屬性名的首字母必須大寫。例如，對(duì) Double 類型的屬性 weight 的 mutator 方法體可能是： public void setWeight(Double weight) 相似的設(shè)計(jì)模式也用于訪問(wèn)器方法的創(chuàng)建。 4．這個(gè)語(yǔ)句導(dǎo)入將在本頁(yè)中使用的標(biāo)簽庫(kù)，并分配給它一個(gè)前綴。要編寫 JavaBean，類必須是具體類和公共類，并且具有無(wú)參數(shù)的構(gòu)造器（ NONARGS CONSTRUCTOR）。當(dāng)一個(gè)客戶請(qǐng)求 JSP 頁(yè)面時(shí)，容器將頁(yè)面翻譯成 Java servlet 源代 碼文件，并將它編譯成 Java 類文件 —— 就象你寫的servlet 文件一樣。 它們喜歡 HTML設(shè)計(jì)人員處理表現(xiàn)層的工作，而 Java 工程師則專注于業(yè)務(wù)邏輯。 JavaServer Pages： 雖然 servlets 對(duì) CGI 程序來(lái)說(shuō)前進(jìn)了一大步，但它也不是萬(wàn)能靈藥。但和 CGI 程序不同，并不是針對(duì)每個(gè)請(qǐng)求都要?jiǎng)?chuàng)建一個(gè)新的 servlet。它接受請(qǐng)求并產(chǎn)生響應(yīng)。 CGI 定義了一套關(guān)于什么信息將作為環(huán)境變量傳遞，以及它希望怎樣使用標(biāo)準(zhǔn)輸入和輸出的慣例。 定義： 靜態(tài)內(nèi)容直接來(lái)自于文本或數(shù)據(jù)文件，比如 HTML或者 JPEG 文件。 URL重寫是在頁(yè)面地址中存儲(chǔ)一個(gè)特殊的標(biāo)記， Java 服務(wù)器可以用它來(lái)跟蹤用戶 。 一旦服務(wù)器接收到請(qǐng)求，它就要產(chǎn)生一個(gè) HTTP 響應(yīng)。這使應(yīng)用程序很容易創(chuàng)建 HTTP 請(qǐng)求。因?yàn)樗鼈冎烂恳粋€(gè)連接的狀態(tài)，以及每一個(gè)使用它的人。 超文本傳輸協(xié)議 (HTTP)： 當(dāng)兩個(gè)國(guó)家之間進(jìn)行調(diào)解時(shí)，外交官們總是遵循一定的正式協(xié)議。某些框 架被限制于專門的開發(fā)環(huán)境中。開發(fā)傳統(tǒng)桌面應(yīng)用的開發(fā)人員更習(xí)慣于那些可以涵蓋應(yīng)用開發(fā)同一性的工具包和開發(fā)環(huán)境。 JSP 頁(yè)面僅在修改后第一次被訪問(wèn)時(shí)，才會(huì)被轉(zhuǎn)換成 servlet 并進(jìn)行編譯；載入到內(nèi)存中、初始化和執(zhí)行遵循 servlet 的一般規(guī)則。 瀏覽器根本不 “ 支持 ” JSP它們看到的只是 JSP 頁(yè)面的輸出。因此： 我如何將 Swing組件用到 JSP 頁(yè)面呢？ 畢業(yè)設(shè)計(jì)外文翻譯 4 所有 JSP 兼容的服務(wù)器必須支持這些標(biāo)準(zhǔn)。因此，在后續(xù)版本中，這項(xiàng)技術(shù)能夠得到協(xié)調(diào)的改進(jìn)。和常規(guī) HTML 頁(yè)面一樣， JSP 頁(yè)面依舊可以包括用于JavaScript 的 SCRIPT 標(biāo)簽。 畢業(yè)設(shè)計(jì)外文翻譯 3 （ 2） JSP 由靜態(tài) HTML、專用的 JSP 標(biāo)簽和 Java 代碼組成。 JSP 的一項(xiàng)優(yōu)勢(shì)是動(dòng)態(tài)部分用 Java 編寫，而 Java 已經(jīng)在聯(lián)網(wǎng)、數(shù)據(jù)庫(kù)訪問(wèn)、分布式對(duì)象等方面擁有廣泛的 API，而 PHP 需要學(xué)習(xí)全新的、應(yīng)用相對(duì)廣泛的語(yǔ)言。例如，盡管 .NET的 C語(yǔ)言設(shè)計(jì)優(yōu)良，且和 Java 類似，但熟悉核心 C語(yǔ)法和眾多工具庫(kù)的程序員很少。 與 .NET 和 Active Server Pages (ASP)相比 .NET 是 Microsoft 精心設(shè)計(jì)的一項(xiàng)技術(shù)。 ” 在此 , Gosling的抱怨顯示出，他感到這個(gè)公司會(huì)從其他公司那里拿走技術(shù) ,用于他們自己的目的 .但你猜這次怎么樣 ?這次鞋子穿在了另一只腳上。依據(jù)開發(fā)團(tuán)隊(duì)的大小，及項(xiàng)目的復(fù)雜程度，可以對(duì)靜態(tài) HTML和動(dòng)態(tài)內(nèi)容進(jìn)行弱分離（ weaker separation）和強(qiáng)分離（ stronger separation）。 畢業(yè)設(shè)計(jì)外文翻譯 1 中文翻譯 JSP 技術(shù)概述與應(yīng)用框架 作者 : Zambon, Giulio/ Sekler, Michael 出處 : SpringerVerlag New York Inc 一、 JSP 的好處 JSP 頁(yè)面最終會(huì)轉(zhuǎn)換成 servler。 JSP 中可以使用常規(guī)的 HTML：沒有額外的反斜杠，沒有額外的雙引號(hào)，也沒有暗含的 Java 語(yǔ)法。對(duì)于大型的項(xiàng)目，這種劃分極為重要。在討論過(guò)程中 ,研討會(huì)的主席提出了 Jini 的議題 ,這在當(dāng)時(shí)是一項(xiàng)新的 Java技術(shù) .主席向該經(jīng)理詢問(wèn)他的想法