【正文】 它們用在航空業(yè)、電子商務(wù)、在線銀行、 web 搜索引擎、門(mén)戶、大型金融網(wǎng)站、以及成百上千您日常光顧的其他網(wǎng)站。 問(wèn)題的第二個(gè)來(lái)源是，一些 CGI程序用不自動(dòng)檢查數(shù)組和字符串邊界的語(yǔ)言編寫(xiě)而成 。如果項(xiàng)目變得極為龐大，錯(cuò)綜復(fù)雜，他們或許希望使用Enterprise JavaBeans 來(lái)封裝他們的商業(yè)邏輯。其次，這兩個(gè)國(guó)家的貨幣對(duì)美元的匯率都極為不利。因此，通過(guò)使用 servelt 和 jsp，我們可以從免費(fèi)或廉價(jià)的服務(wù)器開(kāi)始，在項(xiàng)目獲得初步成功后，在移植到更高性能或高級(jí)管理工具的昂貴的服務(wù)器上。 現(xiàn)在的趨勢(shì)是凡使用 B/S 架構(gòu)的應(yīng)用管理軟件，只需安裝在 Linux 服務(wù)器上即可，而且安全性高。 目前，軟件系統(tǒng)的改進(jìn)和升級(jí)越來(lái)越頻繁， B/S 架構(gòu)的產(chǎn)品明顯體現(xiàn)著更為方便的特性。它是隨著 Inter技術(shù)的興起，對(duì) C/S 結(jié)構(gòu)的一種變化或者改進(jìn)的結(jié)構(gòu)。所有主要的 Web 服務(wù)器。 Servlet 和 Jsp 技術(shù)概要 軟件工程 081 婁文 520813130116 13 便利 Servelt 提供大量的基礎(chǔ)構(gòu)造，可以自動(dòng)分析和解碼 HTML 的表單數(shù)據(jù)，讀取和設(shè)置 HTTP 報(bào)頭，處理 cookie，跟蹤會(huì)話，以及其他次類(lèi)高級(jí)功能。如果 CGI 程序自身相對(duì)比較簡(jiǎn)短，那么啟動(dòng)進(jìn)程的開(kāi)銷(xiāo)會(huì)占用大部分執(zhí)行時(shí)間。顯然，這樣很愚蠢；這種情況下，我們需要與數(shù)據(jù)庫(kù)進(jìn)行會(huì)話。 頁(yè)面由頻繁改變的數(shù)據(jù)導(dǎo)出。 動(dòng)態(tài)構(gòu)建網(wǎng)頁(yè)的原因 預(yù)先建立的文檔可以滿足客戶的許多請(qǐng)求，服務(wù)器無(wú)需調(diào)用 servlet 就可以處理這些請(qǐng)求。 （ 4） 向客戶發(fā)送顯式數(shù)據(jù)（即文檔）。 HTTP 信息包括 cookie、瀏覽器所能識(shí)別的媒體類(lèi)型和壓縮模式等。 關(guān)鍵字 ： JSP 技術(shù)， Servlet， HTTP 服務(wù) 的功能 Servlets 是運(yùn)行在 Web 或應(yīng)用服務(wù)器上的 Java 程序，它是一個(gè)中間層，負(fù)責(zé)連接來(lái)自 Web瀏覽器或其他 HTTP客戶程序的請(qǐng)求和 HTTP服務(wù)器上的數(shù)據(jù)庫(kù)或應(yīng)用程序。 you need to talk to the database. Going from the client to the Web tier to the database (a threetier approach) instead of from an applet directly to a database (a twotier approach) provides increased flexibility and security with little or no performance penalty. After all, the database call is usually the ratelimiting step, so going through the Web server does not slow things down. In fact, a threetier approach is often faster because the middle tier can perform caching and connection pooling. Servlet 和 Jsp 技術(shù)概要 軟件工程 081 婁文 520813130116 4 In principle, servlets are not restricted to Web or application servers that handle HTTP requests but can be used for other types of servers as well. For example, servlets could be embedded in FTP or mail servers to extend their functionality. And, a servlet API for SIP (Session Initiation Protocol) servers was recently standardized (see In practice, however, this use of servlets has not caught on, and we39。t speak HTTP or return results in HTML, so the Web browser can39。 If need differently only, server connection specially , realize longrange maintenance and upgrading and share. So client puter more and more thin , and server more and more fat is the direction of main stream of future informative development. In the future, software upgrading and maintenance will be more and more easy , and use can more and more simple, this is for user manpower , material resources, time and cost save is obvious , it is astonishing. Therefore defend and escalate revolutionary way is the client puter it is thin , is fat server. ( 2 ) Cost reduction, it is more to select. All know windows in the puter of top of a table on nearly one Tong world, browser has bee standard disposition, but on server operating system, windows is in absolute dominance position not. Current tendency is the application management software that uses the configuration of B/S all , need to install only in Linux server on , and safety is high. The so server option of operating system is many, no matter choosing those operating system, can let the most of ones use windows in order to the puter of top of a table of operating system does not get influence, this for make most popular free Linux operating system develop fast, Linux except operating system is free besides, it is also free to link database, this kind of option is very pupular. Say, many persons on daily, Sina website s , so long as having installed browser for can , and what need not know the server of Sina website to use is that what operating system, and in fact the most of websites do not use windows operating system really, but the puter of user is most of as installing to be windows operating system. ( 3 ) Application server operation data load value paratively. Servlet 和 Jsp 技術(shù)概要 軟件工程 081 婁文 520813130116 7 Since B/S configures management, software installation in server end ( Server ) on, it is been all right that work administrator need to manage server only, the user interface major logic of general affairs in server ( Server ) end pass through WWW browser pletely realization, lose the logic of general affairs very much in front( Browser) realization, all customer ends has only browser, work administrator need to do hardware maintenance only. But application server operation data load is heavier, once occuring server collapse to wait for problem, consequence is unimaginable. Therefore a lot of units have database to stock server , are ready for any eventuality. 5． Inexpensive A number of free or very inexpensive Web servers are good for development use or deployment of low or mediumvolume Web sites. Thus, with servlets and JSP you can start with a free or inexpensive server and migrate to more expensive servers with highperformance capabilities or advanced administration utilities only after your project meets initial success. This is in contrast to many of the other CGI alternatives, which require a significant initial investment for the purchase of a proprietary package. Price and portability are somewhat connected. For example, Marty tries to keep track of the countries of readers that send him questions by . India was near the top of the list, probably 2 behind the . Marty also taught one of his JSP and servlet training courses (see in Manila, and there was great interest in servlet an