【導(dǎo)讀】JSP是由SunMicrosystems公司倡導(dǎo)、許多公司參與一起。建立的一種動態(tài)網(wǎng)頁技術(shù)標(biāo)準(zhǔn)。JSP技術(shù)有點類似ASP技術(shù)，它是在傳統(tǒng)的網(wǎng)。頁HTML文件中插入Java程序段和JSP標(biāo)記，從。網(wǎng)頁還能通過tags和scriptlets訪問存在于服務(wù)端的資源的應(yīng)。JSP將網(wǎng)頁邏輯與網(wǎng)頁設(shè)計和顯示分離，支持可重用的基于組件的設(shè)計，使基于Web的應(yīng)用程序的開發(fā)變得迅速和容易。行結(jié)果連同JSP文件中的HTML代碼一起返回給客戶。以操作數(shù)據(jù)庫、重新定向網(wǎng)頁等，以實現(xiàn)建立動態(tài)網(wǎng)頁所需要的功能。JSP的1999年9月推出的，12月又推出了。JSP頁面由HTML代碼和嵌入其中的Java代碼所組成。JavaServlet是JSP的技術(shù)基礎(chǔ)，而且大型的Web應(yīng)用程序的開發(fā)需。要JavaServlet和JSP配合才能完成。JSP具備了Java技術(shù)的簡單易用，完全。的面向?qū)ο?，具有平臺無關(guān)性且安全可靠，主要面向因特網(wǎng)的所有特點。在這一點上Java比PHP更出色，除了系統(tǒng)之外，多臺服務(wù)器進行集群和負(fù)載均衡，到多臺Application進行事務(wù)處理，消息處理，一臺服務(wù)器到無數(shù)臺服務(wù)器，Java顯示了一個巨大的生命力。器結(jié)束，被稱為一個會話。

　　

【正文】 er. JSP technology vulnerable (1) and the same ASP, Java is the advantage of some of its fatal problem. It is precisely because in order to crossplatform functionality, in order to extreme stretching capacity, greatly increasing the plexity of the product. (2) Java39。s speed is class to plete the permanent memory, so in some cases by the use of memory pared to the number of users is indeed a minimum cost performance. On the other hand, it also needs disk space to store a series of. Java documents and. Class, as well as the corresponding versions of documents. JSP six builtin objects: request, response, out, session, application, config, pagecontext, page, exception. 1. Request for: The object of the package of information submitted by users, by calling the object corresponding way to access the information package, namely the use of the target users can access the information. 2. Response object: The customer39。s request dynamic response to the client sent the data. 三 . session object 1. What is the session: session object is a builtin objects JSP, it in the first JSP pages loaded automatically create, plete the conversation of management. From a customer to open a browser and connect to the server, to close the browser, leaving the end of this server, known as a conversation. When a customer visits a server, the server may be a few pages link between repeatedly, repeatedly refresh a page, the server should be through some kind of way to know this is the same client, which requires session object. 2. session object ID: When a customer39。s first visit to a server on the JSP pages, JSP engines produce a session object, and assigned a String type of ID number, JSP engine at the same time, the ID number sent to the client, stored in Cookie, this session objects, and customers on the establishment of a onetoone relationship. When a customer to connect to the server of the other pages, customers no longer allocated to the new session object, until, close your browser, the clientserver object to cancel the session, and the conversation, and customer relationship disappeared. When a customer reopen the browser to connect to the server, the server for the customer to create a new session object. 四 . aplication target 1. What is the application: Servers have launched after the application object, when a customer to visit the site between the various pages here, this application objects are the same, until the server is down. But with the session difference is that all customers of the application objects are the same, that is, all customers share this builtin application objects. 2. application objects monly used methods: (1) public void setAttribute (String key, Object obj): Object specified parameters will be the object obj added to the application object, and to add the subject of the designation of a keyword index. (2) public Object getAttribute (String key): access to application objects containing keywords for. 五 . out targets out as a target output flow, used to client output data. out targets for the output data. 六 . Cookie 1. What is Cookie: Cookie is stored in Web server on the user39。s hard drive section of the text. Cookie allow a Web site on the user39。s puter to store information on and then get back to it. For example, a Web site may be generated for each visitor a unique ID, and then to Cookie in the form of documents stored in each user39。s machine. If you use IE browser to visit Web, you will see all stored on your hard drive on the Cookie. They are most often stored in places: c: \ windows \ cookies (in Window2021 is in the C: \ Documents and Settings \ your user name \ Cookies) Cookie is keyword key = value value to preserve the format of the record. 2. Targets the creation of a Cookie, Cookie object called the constructor can create a Cookie. Cookie object constructor has two string parameters: Cookie Cookie name and value. Cookie c = new Cookie ( username, john)。 3. If the JSP in the package good Cookie object to send to the client, the use of the response addCookie () method. Format: (c) 4. Save to read the client39。s Cookie, the use of the object request getCookies () method will be implemented in all client came to an array of Cookie objects in the form of order, to meet the need to remove the Cookie object, it is necessary to pare an array cycle Each target keywords.