【正文】 使用 JSP技術(shù)可以很方便地將一大堆 JSP頁面組合成為一個(gè) Web應(yīng)用程序。 和傳統(tǒng)的 CGI相比較 ,JSP有相當(dāng)?shù)膬?yōu)勢(shì)。這樣 ,當(dāng)網(wǎng)站的訪問者請(qǐng)求一個(gè) JSP頁時(shí) ,在它不知道的情況下 ,一個(gè)已經(jīng)生成的、預(yù)編譯過的 Servlet實(shí)際上將完成所有的工作 ,非常隱蔽而又高效。 Beans可以是 JavaBeans或 EJB組件。 Java開發(fā)者不僅可以創(chuàng)建和使用 JavaBeans,還能在 JSP頁中使用 Java語言來更精密地控制基于底層 JavaBeans的表達(dá)邏輯。 作為一種以組件為中心的開發(fā)平臺(tái) ,JSP出現(xiàn)了。簡(jiǎn)而言之 ,隨著Web應(yīng)用程序的復(fù)雜性不斷提升 ,以頁面為中心的開發(fā)方式的局限性變得明顯起來。在腳本環(huán)境中書寫的表達(dá)邏輯被鎖在頁面內(nèi) ,只有通過剪切和粘貼才能被重用。 D. JSP的機(jī)制 要理解 JSP怎樣聯(lián)合以上各種所提到的技術(shù)的優(yōu)點(diǎn) ,來輕而易舉地實(shí)現(xiàn)各種效果 ,用戶必須首先了解“組件為中心的網(wǎng)頁開發(fā)”和“頁面為中心的網(wǎng)頁開發(fā)”的區(qū)別。解釋式的動(dòng)態(tài)網(wǎng)頁開發(fā)工具如 ASP、 PHP3等由于速度等原因已經(jīng)滿足不了當(dāng)前大型電子商務(wù)應(yīng)用的需要了 ,傳統(tǒng)的開發(fā)技 術(shù)都在向編譯執(zhí)行的方式改變 ,如 ASP→ ASP+； PHP3→PHP4。分開內(nèi)容和顯示邏輯的好處是 ,更新頁面外觀的人員不必懂得 Java代碼 ,而更新 JavaBeans類的人員也不必是設(shè)計(jì)網(wǎng)頁的行家里手 ,就可以用帶 JavaBeans類的JSP 頁面來定義 Web模板 ,以建立一個(gè)由具有相似的外觀的頁面組成的網(wǎng)站。JSP把 Java作為默認(rèn)的腳本語言 ,然而 ,就像 ASP可以使用其他語言 (如 JavaScript和VBScript)一樣 ,JSP規(guī)范也允許使用其他語言。甚至 ASP(來自于前述經(jīng)理所在公司 的一項(xiàng)產(chǎn)品 )都在 JSP 出現(xiàn)之前推廣了這種方式。在討論過程中 ,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)理詢問他的想法 .他繼續(xù)說 ,他們會(huì)持續(xù)關(guān)注這項(xiàng)技術(shù) ,如果這項(xiàng)技術(shù)變得流行起來 ,他們會(huì)遵循公司的“接受并擴(kuò)充 (embrace and extend)”的策略 .此時(shí) , Gosling隨意地插話說“你的意思其實(shí)就是不接受且不擴(kuò)充(disgrace and distend)。 但 Java Servlet也不是沒有缺點(diǎn) ,和傳統(tǒng)的 CGI、 ISAPI、 NSAPI 方式相同 ,JavaServlet是利用輸出 HTML 語句來實(shí)現(xiàn)動(dòng)態(tài)網(wǎng)頁的 ,如果用 Java Servlet來開發(fā)整個(gè)網(wǎng)站 ,動(dòng)態(tài)部分和靜態(tài)頁面的整合過程簡(jiǎn)直就是一場(chǎng)惡夢(mèng)。 Servlet其實(shí)和傳統(tǒng)的 CGI、 ISAPI、 NSAPI 等 Web程序開發(fā)工具的作用是相同的 ,在使用 Java Servlet以后 ,用戶不必再使用效率低下的 CGI方式 ,也不必使用只能在某個(gè)固定 Web 服務(wù)器平臺(tái)運(yùn)行的 API 方式來動(dòng)態(tài)生成 Web頁面。我們總是希望用適當(dāng)?shù)墓ぞ咄瓿上鄬?duì)應(yīng)的工作 ,僅僅是 servlet并不能填滿您的工具箱。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)。 可以對(duì)開發(fā)團(tuán)隊(duì)進(jìn)行劃分。和單獨(dú)使用 servler相比 ,JSP提供下述好處 : JSP中 HTML的編寫與維護(hù)更為簡(jiǎn)單。因而 ,從根本上 ,JSP頁面能夠執(zhí)行的任何任務(wù)都可以用 servler來完成。 JSP與Microsoft的 ASP 技術(shù)非常相似。 JSP為創(chuàng)建高度動(dòng)態(tài)的 Web應(yīng)用提供了一個(gè)獨(dú)特的開發(fā)環(huán)境。 hand over with each other, and the manifestation result in dynamic state bornly, mixing with the HTML page of the static state HTML code. The Beans can be JavaBeans or module of EJBs. Moreover, the more plicated claim model can see make from is request other JSP pages of the page call sign or Java Servlets. The engine of JSP wants to chase the code of Java that the label of JSP, code of Java in the JSP page even all converts into the big piece together with the static state HTML contents actually. These codes piece was anized the Java Servlet that customer can not see to go to by the engine of JSP, then the Servlet edits and translate them automatically byte code of Java. Thus, the visitant that is the website requests a JSP page, under the condition of it is not knowing, an already born, the Servlet actual full general that prepared to edit and translate pletes all works, very concealment but again and efficiently. The Servlet is to edit and translate of, so the code of JSP in the web page does not need when the every time requests that page is explain. The engine of JSP need to be edit and translate after Servlet the code end is modify only once, then this Servlet that editted and translate can be carry out. The in view of the fact JSP engine auto is born to edit and translate the Servlet also, need not procedure member begins to edit and translate the code, so the JSP can bring vivid sex that function and fast developments need that you are efficiently. Compared with the traditional CGI, the JSP has the equal advantage. First, on the speed, the traditional procedure of CGI needs to use the standard importation of the system to output the equipments to carry out the dynamic state web page born, but the JSP is direct is mutually the connection with server. And say for the CGI, each interview needs to add to add a progress to handle, the progress build up and destroy by burning constantly and will be a not small burden for calculator of be the server of Web. The next in order, the JSP is specialized to develop but design for the Web of, its purpose is for building up according to the Web applied procedure, included the norm and the tool of a the whole set. Use the technique of JSP can bine a lot of JSP pages to bee a Web application procedure very expediently. 譯 文 介紹 Java Server Pages(JSP)是一種基于 web 的腳本編程技術(shù) ,類似于網(wǎng)景公司的服務(wù)器端 Java 腳本語言 serverside JavaScript(SSJS)和微軟的 Active Server Pages(ASP)。s usual embrace and extend strategy. At this point, Gosling lightheartedly interjected You mean disgrace and distend. Now, the grievance that Gosling was airing was that he felt that this pany would take technology from other panies and suborn it for their own purposes. But guess what? The shoe is on the other foot here. The Java munity did not invent the idea of designing pages as a mixture of static HTML and dynamic code marked with spec