【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 Web 應用程序。 和傳統(tǒng)的 CGI 相比較， JSP 有相當?shù)膬?yōu)勢。這樣，當網(wǎng)站的訪問者請求一個 JSP 頁時，在它不知道的情況下，一個已經(jīng)生成的、預編譯過的 Servlet 實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 的表達邏輯。 作為一種以組件為中心的開發(fā)平臺， JSP 出現(xiàn)了。簡而言之，隨著 Web 應用程序的復雜性不斷提升，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)境中書寫的表達邏輯被鎖在頁面內(nèi)，只有通過剪切和粘貼才能被重用。 JSP 的機制 要理解 JSP怎樣聯(lián)合以上各種所提到的技術(shù)的優(yōu)點，從而輕而易舉地實現(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)滿足不了當前大型電子商務應用的需要了，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→PHP 4。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，以建立一個由具有相似的外觀的頁面組 成的網(wǎng)站。JSP 把 Java 作為默認的腳本語言，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)理所在公司的一項產(chǎn)品 )都在 JSP 出現(xiàn)之前推廣了這種方式。 他們會持續(xù)關(guān)注這項技術(shù) ,如果這項技術(shù)變得流行起來 ,他們會遵循公司的 “ 接受并擴充 (embrace and extend)” 的策略 .此時 , Gosling 隨意地插話說 “ 你的意思其實就是不接受且不擴充 (disgrace and distend)。 許多年前， Marty 受到邀請 ,參加一個有關(guān)軟件技術(shù)的小型研討會 .坐 在 Marty 旁邊的人是 James Gosling Java 編程語言的發(fā)明者。得益于 Java 的跨平臺的特性， Servlet 也是平臺無關(guān)的，實際上，只 要符合 Java Servlet 規(guī)范， Servlet 是完全與平臺無關(guān)且是與 Web 服務器無關(guān)的。使用 JSP 標識或者小腳本來生成頁面上的動態(tài)內(nèi)容 (內(nèi)容是根據(jù)請求來變化的 )。事實上， 幾乎所有 8 的項目都會同時用到這兩種技術(shù)。 Web 開發(fā)人員可以將經(jīng)理集中在表示層（ presentation layer）上。 能夠使用標準的網(wǎng)站開發(fā)工具。問題不在于技術(shù)的能力，而是二 者在便利性、生產(chǎn)率和可維護性上的不同。下面我們簡單的對它進行介紹。 本文將介紹 JSP 相關(guān)的知識，以及 JavaBean 的相關(guān)內(nèi)容，當然都是比較粗略的介紹其中的基本內(nèi)容，僅僅起到拋磚引玉的作用，如果讀者需要更詳細的信息，請參考相應的JSP 的書籍。盡管 JSP 規(guī)范是由 Sun 公司制定的，但任何廠商都可以在自己的系統(tǒng)上實現(xiàn) JSP。PHP3 → PHP4. In the JSP norm book, did not request the procedure in the JSP code part( be called the Scriptlet) and must write with the Java definitely. Actually, have some engines of JSP are adoptive other script languages such as the EMAC Script, etc., but actually this a few script languages also are to set up on the Java, edit and translate for the Servlet to carry out of. Write according to the norm of JSP, have no Scriptlet of relation with Java also is can of, however, mainly lie in the ability and JavaBeans, the Enterprise JavaBeanses because of the JSP strong function to work together, so even is the Scriptlet part not to use the Java, edit and translate of performance code also should is related with Java. MECHANISM To prehend the JSP how unite the technical advantage that above various speak of, e to carry out various result easily, the customer must understand the differentiation of the module develops for the web page of the center and the page develops for the web page of the center first. The SSJS and ASP are all in several year ago to release, the work of that time is still very young, no one knows to still have in addition to making all business, datas and the expression logic enter the original web page entirely heap what better solve the method. This 5 kind of model that take page as the center studies and gets the very fast developme nt easily. However, along with change of time, the people know that this kind of method is unwell in set up large, the Web that can upgrade applies the procedure. The expression logic write in the script environment was lock in the page, only passing to shear to slice and glue to stick then can drive heavy use. Express the logic to usually mix together with business and the data logics, when this makes be the procedure member to try to change an external appearance that applies the procedure but do not want to break with its llied business logic, apply the procedure of maintenance be like to walk the similar difficulty on the eggshell. In fact in the business enterprise, heavy use the application of the module already through very mature, no one would like to rewrite those logics for their applied and sketch the designer handed over to the implement work of their design the Web plait the one who write, make they have to double work Usually is the handicraft plait to write, because have no fit tool and can carry the script and the HTML contents knot to the server to put together. Chien but speech, apply the plexity of the procedure along with the Web to promote continuously, the development method that take page as the center limits sex to bee to get up obviously. At the same time, the people always at look for the better method of build up the Web application procedure, the module spreads in customer39。s concern. JSP provided a special development environment for the Web application that establishes the high dynamic state. According to the Sun parlance, the JSP can adapt to include the Apache WebServer,