Example of ServletContext to get the initialization parameter

Example of ServletContext to get the initialization parameter

we are getting the initialization parameter from the web.xml file and printing the value of the initialization parameter. Notice that the object of ServletContext represents the application scope. So if we change the value of the parameter from the web.xml file, all the servlet classes will get the changed value. So we don't need to modify the servlet. So it is better to have the common information for most of the servlets in the web.xml file by context-param element. Let's see the simple example:

DemoServlet.java

1.     import java.io.*;  

2.     import javax.servlet.*;  

3.     import javax.servlet.http.*;  

4.       

5.       

6.     public class DemoServlet extends HttpServlet{  

7.     public void doGet(HttpServletRequest req,HttpServletResponse res)  

8.     throws ServletException,IOException  

9.     {  

10.   res.setContentType("text/html");  

11.   PrintWriter pw=res.getWriter();  

12.     

13.   //creating ServletContext object  

14.   ServletContext context=getServletContext();  

15.     

16.   //Getting the value of the initialization parameter and printing it  

17.   String driverName=context.getInitParameter("dname");  

18.   pw.println("driver name is="+driverName);  

19.     

20.   pw.close();  

21.     

22.   }}  

web.xml

1.     <web-app>  

2.       

3.     <servlet>  

4.     <servlet-name>sonoojaiswal</servlet-name>  

5.     <servlet-class>DemoServlet</servlet-class>  

6.     </servlet>  

7.       

8.     <context-param>  

9.     <param-name>dname</param-name>  

10.   <param-value>sun.jdbc.odbc.JdbcOdbcDriver</param-value>  

11.   </context-param>  

12.     

13.   <servlet-mapping>  

14.   <servlet-name>sonoojaiswal</servlet-name>  

15.   <url-pattern>/context</url-pattern>  

16.   </servlet-mapping>  

17.     

18.   </web-app>  

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