1、1 Combining JSP and Servlets The technology of JSP and Servlet is the most important technology which use Java technology to exploit request of server, and it is also the standard which exploit business application .Java developers prefer to use it for a variety of reasons, one of which is already f
2、amiliar with the Java language for the development of this technology are easy to learn Java to the other is a preparation, run everywhere to bring the concept of Web applications, To achieve a one-prepared everywhere realized. And more importantly, if followed some of the principles of good design,
3、 it can be said of separating and content to create high-quality, reusable, easy to maintain and modify the application. For example, if the document in HTML embedded Java code too much (script), will lead the developed application is extremely complex, difficult to read, it is not easy reuse, but a
4、lso for future maintenance and modification will also cause difficulties. In fact, CSDN the JSP / Servlet forum, can often see some questions, the code is very long, can logic is not very clear, a large number of HTML and Java code mixed together. This is the random development of the defects. Early
5、 dynamic pages mainly CGI (Common Gateway Interface, public Gateway Interface) technology, you can use different languages of the CGI programs, such as VB, C / C + + or Delphi, and so on. Though the technology of CGI is developed and powerful, because of difficulties in programming, and low efficien
6、cy, modify complex shortcomings, 2 it is gradually being replaced by the trend. Of all the new technology, JSP / Servlet with more efficient and easy to program, more powerful, more secure and has a good portability, they have been many people believe that the future is the most dynamic site of the
7、future development of technology. Similar to CGI, Servlet support request / response model. When a customer submit a request to the server, the server presented the request Servlet, Servlet responsible for handling requests and generate a response, and then gave the server, and then from the server
8、sent to the customer. And the CGI is different, Servlet not generate a new process, but with HTTP Server at the same process. It threads through the use of technology, reduce the server costs. Servlet handling of the request process is this: When received from the clients request, calling service me
9、thods, 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 complex, in fact, simply said to Servlet is a Java class. And the general category of the d
10、ifference is that this type operating in a Servlet container, which can provide session management and targeted life-cycle 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 cross-p
11、latform 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. 3 It allows conventional static and dynamic HTML content generated by combining an HTML page looks like, but
12、 as a Servlet to run. There are many commercial 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 pl
13、aced, do not have to compile, 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
14、 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 compiler, 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, as shown below: Figure 1: Calling the process of JSP pages
