Servlets & jsp Overview

• 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

Servlet Loading
1. Load on Startup
2. Using URL pattern
3. From Another Servlet/jsp

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>");
}
}

<servlet>
<servlet-name>hello</servlet-name>
<servlet-class>ReadInitParamValues</servlet-class>
<init-param>
<param-name>pearlcity</param-name>
<param-value>Hyderabad</param-value>
</init-param>
<init-param>
<param-name>monument</param-name>
<param-value>Charminar</param-value>
</init-param>
<init-param>
<param-name>mangoCost</param-name>
<param-value>250.5</param-value>
</init-param>
<init-param>
<param-name>numberOfMangoes</param-name>
<param-value>30</param-value>
</init-param>
</servlet>
<servlet-mapping>
<url-pattern>/bharat</url-pattern>
</servlet-mapping>

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>

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();
}}

<servlet>
<servlet-class>ReadInitParamValues</servlet-class>
<init-param>
<param-name>pearlcity</param-name>
<param-value>Hyderabad</param-value>
</init-param>
<init-param>
<param-name>monument</param-name>
<param-value>Charminar</param-value>
</init-param>
<init-param>
<param-name>mangoCost</param-name>
<param-value>250.5</param-value>
</init-param>
<init-param>
<param-name>numberOfMangoes</param-name>
<param-value>30</param-value>
</init-param>
</servlet>
<servlet-mapping>
<url-pattern>/ftd</url-pattern>
</servlet-mapping>
Defining a Servlet

Remaining Tags in Web.xml
https://docs.oracle.com/cd/E14571_01/web.1111/e13712/web_xml.htm#WBA
PP515

Session Management
1. HTML Hidden Field
2. URL Rewriting
3. Cookies
4. Session Management API

Servlet Filters and Listeners
e.g. For Request and Response trackers..

Listeners
Useful when any kind of action needs to be done when certain action taken
place

JSP tags
1. Declaration <%! %> == init Method
2. Script let <% %> == Service Method in Serlvet executes for each request
3. Display <%= %>

Jsp Impilict Objects
1. Request
2. Response
3. Session
4. Page
5. exception
6. Application
7. Out
8. Config

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.

Servlets & jsp Overview

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