Create Servlet Program using post method with HTML Form

Create Servlet Program using post method using HTML Form:-

mostly we design HTML form on the JSP Web page but it is an example to design HTML form elements under servlet.

Example for addition:-

Create servlet and first design User-interface on doGet() and Write code on doPost():-

package scs;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

@WebServlet("/DesignExample")

public class DesignExample extends HttpServlet {

private static final long serialVersionUID = 1L;

           /**

     * @see HttpServlet#HttpServlet()

     */

    public DesignExample() {

        super();

        // TODO Auto-generated constructor stub

    }

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

PrintWriter out = response.getWriter();

out.write("<form action='' method='post'>");

out.write("<input type='text' name='txtnum1' placeholder='Enter p' /><br>");

out.write("<input type='text' name='txtnum2' placeholder='Enter r' /><br>");

out.write("<input type='submit' name='btnsubmit' value='Click' />");

out.write("</form>");

}

/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

PrintWriter out = response.getWriter();

if(request.getParameter("btnsubmit")!=null)

{

int a = Integer.parseInt(request.getParameter("txtnum1"));

int b = Integer.parseInt(request.getParameter("txtnum2"));

int c = a+b;

out.print(c);

}

}

}

Step-1st:-  Create Servlet and Define doGet() and doPost()
Step-2nd:  Design Form  under doGet() and Write Action Code under doPost()
Step3rd:-  Code of doGet():-
 public void doGet(HttpServletRequest request,HttpServletResponse response) throws IOException
    {
           response.setContentType("text/html");
           PrintWriter out = response.getWriter();
           out.write("<form action='' method='post'>");
           out.write("<input type='text' name='txtnum1' placeholder='enter P' /><br><br>");
           out.write("<input type='text' name='txtnum2' placeholder='enter R' /><br><br>");
           out.write("<input type='text' name='txtnum3' placeholder='enter T' /><br><br>");
           out.write("<input type='submit' name='btnsubmit' value='click' />");
           out.write("</form>");      
         }
Step4th:-  code of doPost():-
 public void doPost(HttpServletRequest request,HttpServletResponse response) throws IOException
    {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        float p,r,t,si;
        p = Float.parseFloat(request.getParameter("txtnum1"));
        r = Float.parseFloat(request.getParameter("txtnum2"));
        t = Float.parseFloat(request.getParameter("txtnum3"));
        si = (p*r*t)/100;
        response.sendRedirect("SiServlet?q="+si);
       // out.print("Result is "+si);
         }
Step5th:-
    Code to display output in the text field:-\
     if(request.getParameter("q")!=null)
           {
               out.print("<input type='text' value='"+request.getParameter("q")+"'/>");
           }