【正文】 來(lái)處理。使用 JSP 比用 Servlet 更簡(jiǎn)單。而且， Servlet使用線程，因而可以開(kāi)發(fā)出效率更高的 Web應(yīng)用。 Servlet處理請(qǐng)求的過(guò)程是這樣的：當(dāng)收到來(lái)自客戶端的請(qǐng)求后，調(diào)用 service 方法，該方法中 Servlet先判斷到來(lái)的請(qǐng) 求是什么類型的（ GET/POST/HEAD?），然后調(diào)用相應(yīng)的處理方法（ doGet/doPost/doHead?）并生成響應(yīng)。 與 CGI相似， Servlet支持請(qǐng)求 /響應(yīng)模型。這就是隨意開(kāi)發(fā)的弊端。 Java 開(kāi)發(fā)者喜歡使用它有多種原因，其一是對(duì)于已經(jīng)熟悉 Java 語(yǔ)言的開(kāi)發(fā)者來(lái)說(shuō)這個(gè)技術(shù)容易學(xué)習(xí)；其二是 Java 把“一次編寫，到處運(yùn)行”的理念帶入到 Web應(yīng)用中，實(shí)現(xiàn)了“一次編寫，到處實(shí)現(xiàn)”。s easy to fet to include the access control code in new pages. 10 This is clearly an application that can benefit from using a bination of JSP pages and the ponent types defined by the servlet specification for the MVC roles. Let39。t yet support this version of the specification, I39。 the HttpServlet class already takes care of HEAD, OPTIONS, and TRACE requests in a way that39。 in other words, it lets you use the most appropriate ponent type for the roles of Model, View and Controller. Servlets, Filters, and Listeners A servlet is a Java class that extends a server with functionality for processing a request and producing a response. It39。s request, calling service methods, the method of Servlet arrival of the first judgement is what type of request (GET / POST / HEAD…), then calls the appropriate treatment (DoGet / doPost / doHead…) and generate a response. Although such a plex, in fact, simply said to Servlet is a Java class. And the general category of the difference is that this type operating in a Servlet container, which can provide session management and targeted lifecycle management. So that when you use the Servlet, you can get all the benefits of the Java platform, including the safety of the management, use JDBC access the database and crossplatform capability. Moreover, Servlet using thread, and can develop more efficient Web applications. JSP technology is a key J2EE technology, it at a higher level of abstraction of a Servlet. 4 It allows conventional static and dynamic HTML content generated by bining an HTML page looks like, but as a Servlet to run. There are many mercial application server support JSP technology, such as BEA WebLogic, IBM WebSphere, JRun, and so on. JSP and Servlet use more than simple. If you have a JSP support for Web servers, and a JSP document, you can put it Fangdao any static HTML files can be placed, do not have to pile, do not have to pack, do not have to ClassPath settings, you can visit as ordinary Web It did visit, the server will automatically help you to do other work. JSP document looks like an ordinary static HTML document, but inside contains a number of Java code. It uses. Jsp the suffix, used to tell the server this document in need of special treatment. When we visit a JSP page, the document will first be translated into a JSP engine Java source files, is actually a Servlet, and piler, and then, like other Servlet, from Servlet engine to handle. Servlet engine of this type loading, handling requests from customers, and the results returned to the customer. After another visit this page to the customer, as long as the paper there have been no changes, JSP engine has been loaded directly call the Servlet. If you have already been modified, it will be once again the implementation of the above process, translate, pile and load. In fact, this is the socalled first person to punishment. Because when the first visit to the implementation of a series of the above process, so will spend some time after such a visit would not. Java servlets offer a powerful API that provides access to all the information about the 5 request, the session, and the application. bining JSP with servlets lets you clearly separate the application logic from the presentation of the application。t implement these methods。re using a container that doesn39。s sent to the client. This makes it easy to centralize tasks that apply to all requests, such as access control, logging, and charging for the content or the services offered by the application. A filter has full access to the body 8 and headers of the request and response, so it can also perform various transformations. One example is pressing the response body if the AcceptLanguage request header indicates that the client can handle a pressed response. A filter can be applied to either a specific servlet or to all requests matching a URL pattern, such a