Servlet and JSP
1 like822 views
This document provides an overview of servlets and JSPs. It discusses how servlets were developed to address disadvantages of CGI programs. Servlets run within a web container and have a lifecycle of init(), service(), and destroy() methods. The document also covers implementing a simple servlet, using HttpServletRequest and HttpServletResponse objects, and configuring servlets in web.xml. It describes how JSPs work by being converted to servlets and discusses JSP directives, actions, and scripting elements.
Ad
More Related Content
What's hot (20)
Similar to Servlet and JSP (20)
Ad
More from Gary Yeh (10)
Ad
Recently uploaded (20)
![Get & Download Wondershare Filmora Crack Latest [2025]](https://cdn.slidesharecdn.com/ss_thumbnails/revolutionizingresidentialwi-fi-250422112639-60fb726f-250429170801-59e1b240-thumbnail.jpg?width=560&fit=bounds)
![Pixologic ZBrush Crack Plus Activation Key [Latest 2025] New Version](https://cdn.slidesharecdn.com/ss_thumbnails/fashionevolution2-250322112409-f76abaa7-250428124909-b51264ff-250504160528-fc2bb1c5-thumbnail.jpg?width=560&fit=bounds)
Servlet and JSP
- 2. Question • Blocking I/O如何處理多個read? • I/O – Blocking I/O – Non-blocking I/O – Asynchronous I/O – Synchronous I/O
- 3. Question • Blocking I/O model recvfrom application System call Process datagram Process blocks in call to recvfrom Wait for data Copy data from kernel to user No datagram ready Datagram ready Copy datagram Copy complete Return OK kernel
- 4. Question • Non-Blocking I/O model recvfrom application System call Process datagram Process repeatedly calls recvfrom waiting for an OK return(polling) Wait for data Copy data from kernel to user No datagram ready Datagram ready Copy datagram Copy complete Return OK kernel EWOULDBLOCK recvfrom System call No datagram readyEWOULDBLOCK
- 5. Question • Asynchronous I/O model recvfrom application System call Signal handler process datagram Process continues executing Wait for data Copy data from kernel to user No datagram ready Datagram ready Copy datagram Copy complete Deliver signal specofied in recvfrom kernel return
- 6. Question • Synchronous I/O • Definition – A synchronous I/O operation causes the requesting process to be blocked until that I/O operation completes.
- 7. Question • How to solve multiple I/O devices? • Use select() A B A Select() device
- 8. Question • 手動讓process休眠 DEFINE_WAIT(my_wqentry); 初始化一個待命佇列項目 void prepare_to_wait(wait_queue_head_t *queue, wait_queue_t *my_wqentry, int state); 將待命佇列項目加進佇列 prepare_to_wait(); 可以開始休眠 schedule(); 重新加入排程 void finish_wait(wait_queue_head_t *queue, wait_queue_t *my_wqentry); 把柱列項目清除
- 9. Question • Asynchronous Notification – 當新資料進來時獲得通知 – 執行優先度低，無法使用輪詢 fcntl(STDIN_FILENO, F_SETOWN, getpid()); 讓核心知道通知對象是誰 fcntl(STDIN_FILENO, FSETFL, oflags | FASYNC); 啟動臨時通知
- 10. Question • 同時存取database – Locking – Timestamp – Multiversion concurrency control
- 11. Outline • Introduction • CGI • Servlet • Implement of Servlet • JSP • Conclusion
- 12. Introduction • You can use JSP or servlet to solve dynamic web page needs. JSP is web page design oriented, and servlet is program designed oriented. Knowing their character can cooperate two expertise and make the achievement better.
- 13. CGI • Common Gateway Interface • A standard method for web server software to delegate the generation of web content to executable files. • Web server send request to external program, and the program response with static file.
- 14. CGI Web Server CGI Program Database Web Browser 1. Request 2. Input data 3. May access database 4. Response as HTML doc Figure: CGI workflow
- 15. CGI • CGI can designed as any computer language. Perl is the most popular. • When server receive a request, it produce a new process to execute CGI program. • Consume many memory. • Each CGI program is isolated.
- 16. Servlet • In order to solve the disadvantage of CGI, servlet is developed. • Servlet is designed to substitute CGI. • The word servlet is composed of “server” and “let”. In Java, “let” means small application. • Servlet is run in server side, and applet is run in client side.
- 17. Servlet Client Browser Web Server Servlet Container Servlet 1. Browser requests page 2. Web server delegates to container 3. Container executes servlet, creating instance if required 4. Servlet executes, generates response 5. Server returns response Figure: Servlet workflow
- 18. Servlet • Web container – Execute JSP and servlet. – Like Java only recognizes JVM, servlet/JSP only recognizes web container. – Parsing HTTP request, create instance like HttpServletRequest、 HttpServletResponse、 HttpSession
- 19. Servlet • Servlet life cycle – void init() • When servlet is first loaded, initialize servlet status – void service() • Serve a request. Can be called multiple times. – void destroy() • Dispose servlet.
- 20. Servlet • Since the output of servlet is HTML, the usage of servlets doesn’t constrain by browser. • No matter how many requests, only one servlet will be loaded into JVM. • When there is a request, there is a thread, not process. • Servlets is persistent until be deystroyed.
- 21. Implement of Servlet • Environment – oracle java jdk 1.7.0 • Add path to environment variables – JAVA_HOME – PATH – CLASSPATH
- 22. Implement of Servlet • Download Apache-Tomcat-7.0.42 • Use tomcat as web server and web container
- 24. Implement of Servlet • javax.servlet – The javax.servlet package contains a number of classes and interfaces that describe and define the contracts between a servlet class and the runtime environment provided for an instance of such a class by a conforming servlet container
- 25. Implement of Servlet • javax.servlet.http – The javax.servlet.http package contains a number of classes and interfaces that describe and define the contracts between a servlet class running under the HTTP protocol and the runtime environment provided for an instance of such a class by a conforming servlet container.
- 26. Implement of Servlet • javax.servlet
- 27. Implement of Servlet • javax.servlet.http
- 28. Implement of Servlet • service() can handle doGet() and doPost() • Get – The request parameter shows on URL – Not proper for password – Not too long data – Good for setting as tags or bookmarks – Don’t change the status of server
- 29. Implement of Servlet • Post – The request parameter is in Body – Good for password – Good for long data – Not proper for tags or bookmarks – May change content of database
- 30. Implement of Servlet • HttpServletRequest – The object of client sending request to server – E.g. Form input data • HttpServletResponse – The object of server responding to client – E.g. Show HTML doc on browser
- 31. Implement of Servlet • HttpServletResponseObjectName.setContentType(“ContentType”) • E.g. res.serContentTyoe(“text/html;charset=Big5”)
- 32. Implement of Servlet • In order to show information on web page, use HttpServletResponse object create a PrintWriter object. • And use PrintWriter to write HTML tags.
- 33. Implement of Servlet • Write web.xml • /WEB-INF/ /classes/ | |HelloServlet.class |web.xml
- 34. Implement of Servlet • Web.xml – Used to configure welcome page、 servlet 、 filter – Run before load servlet url-pattern servlet-name servlet-class
- 35. Implement of Servlet • The result
- 37. JSP • HelloWorld.jsp • A JSP page is basically a web page with traditional HTML and bits of Java code.
- 39. JSP • When a JSP file is accessed, the container converts it into a Java class that implements the javax.servlet.jsp.HttpJspPage interface. The various JSP building blocks are translated into Java code and compiled into a Servlet.
- 40. JSP • The element of JSP can be divided into three kinds – Directive • Definite the static information of web page. – Action • Send data according to the request of client. – Scripting • Small piece of java code. Only execute if client request.
- 42. JSP • Implicit object • Corresponds to an object in servlet • out – corresponds to JspWriter, which associates PrintWriter • Request – corresponds to HttpServletRequest • Response – corresponds to HttpServletResponse
- 43. JSP
- 44. Conclusion • Deal with JSP is easier than with servlet. • Knowing how to write JSP code is helpful in developing server-side web design.