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Servlets & jsp Overview
- 1. By Bhargava
- 3. • Introduction • Servlet Life Cycle • Servlet Loading • Servlet Config and Context • Web.xml (Servlet Definition) • Servlet Session Management (Http Session and Cookies) • Servlet Filters and Listeners • jsp life Cycle • Jsp loading • jsp Implicit Objects • Webcontainer - Tomcat • Servlet/jsp Web Application • Assignments
- 4. Introduction
- 6. Servlet Loading 1. Load on Startup 2. Using URL pattern 3. From Another Servlet/jsp
- 7. Servlet Config and Context - Servlet Config is per Servlet public class SimpleServlet extends GenericServlet { protected String myParam = null; public void init(ServletConfig servletConfig) throws ServletException{ this.myParam = servletConfig.getInitParameter("myParam"); } public void service(ServletRequest request, ServletResponse response) throws ServletException, IOException { response.getWriter().write("<html><body>myParam = " + this.myParam + "</body></html>"); } }
- 9. Servlet Context – This is per web application and these parameters will be shared across the application <web-app> ...... <context-param> <param-name>parametername</param-name> <param-value>parametervalue</param-value> </context-param> ...... </web-app>
- 10. import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class DemoServlet extends HttpServlet{ public void doGet(HttpServletRequest req,HttpServletResponse res) throws ServletException,IOException { res.setContentType("text/html"); PrintWriter pw=res.getWriter(); //creating ServletContext object ServletContext context=getServletContext(); //Getting the value of the initialization parameter and printing it String driverName=context.getInitParameter("dname"); pw.println("driver name is="+driverName); pw.close(); }}
- 11. web.xml
- 13. Remaining Tags in Web.xml https://docs.oracle.com/cd/E14571_01/web.1111/e13712/web_xml.htm#WBA PP515
- 14. Session Management 1. HTML Hidden Field 2. URL Rewriting 3. Cookies 4. Session Management API
- 15. Servlet Filters and Listeners e.g. For Request and Response trackers..
- 16. Listeners Useful when any kind of action needs to be done when certain action taken place
- 17. jsp life cycle
- 18. JSP tags 1. Declaration <%! %> == init Method 2. Script let <% %> == Service Method in Serlvet executes for each request 3. Display <%= %>
- 19. Jsp loading
- 20. Jsp Impilict Objects 1. Request 2. Response 3. Session 4. Page 5. exception 6. Application 7. Out 8. Config
- 21. Web Container – Tomcat
- 22. Assignments 1. Write Web Application for login page should accept user name and password and display the Login Success message. 2. Write web application that accepts the Resume of .docx file and save it in the Web Server. 3. Write web app using jsp’s that should communicate to Servlets.
Editor's Notes
- Cookies are small piece of information that is sent by web server in response header and gets stored in the browser cookies. When client make further request, it adds the cookie to the request header and we can utilize it to keep track of the session. We can maintain a session with cookies but if the client disables the cookies, then it won’t work. Session Management API is built on top of above methods for session tracking. Some of the major disadvantages of all the above methods are:Most of the time we don’t want to only track the session, we have to store some data into the session that we can use in future requests. This will require a lot of effort if we try to implement this. All the above methods are not complete in themselves, all of them won’t work in a particular scenario. So we need a solution that can utilize these methods of session tracking to provide session management in all cases.