request.getparameter(), Retrieve Parameters

    Example of request.getparameter(), Retrieve Parameters from HTML Form

. index.html

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<font face="verdana" size="2px">    <form action="sum" method="post">        Number1:<input type="text" name="n1"><br>        Number2:<input type="text" name="n2"><br>        <input type="submit" value="Calculate Sum">   </form> </font>

OngetParameter.java

package java4s;

 import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

public class OngetParameter extends HttpServlet  

{

    protected void doPost(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException

            {

                        PrintWriter pw=res.getWriter();

                        res.setContentType("text/html");

                        String n1=req.getParameter("n1");

                        String n2=req.getParameter("n2");

                        int result=Integer.parseInt(n1)+Integer.parseInt(n2);            

                        pw.println("Sum of two numbers " +result);

                        pw.close();

            }

}

web.xml

<web-app>

     <servlet>

       <servlet-name>sumOfTwoNumbers</servlet-name>

       <servlet-class>java4s.OngetParameter</servlet-class>

    </servlet>

    <servlet-mapping>

       <servlet-name>sumOfTwoNumbers</servlet-name>

       <url-pattern>/sum</url-pattern>

    </servlet-mapping>

    <welcome-file-list>

       <welcome-file>index.html</welcome-file>

    </welcome-file-list>

 </web-app>