Dr R Anurekha: servlet

Showing posts with label servlet. Show all posts

Form data and Servlets - Factorial of a number

Simple program to demonstrate accessing form data in servlets. Factorial of a number

// Form to submit number to server

<html>

<head>

<title>HTML Forms and Servlets</title>

<style>

label

{

font-family:vivaldi;

font-size:x-large;

letter-spacing:2px;

line-height:40px;

}

</style>

</head>

<body>

<h2>HTML and Servlets</h2></br>

<label>Enter Number </label>

</br> </br>

<button class="btn" type="button " >Calculate!!! </button>

</center>

</form>

</body>

</html>

// Servlet to access form data and generate response to client browser

import javax.servlet.http.*;

import javax.servlet.*;

import java.io.*;

import java.util.*;

public class Fact extends HttpServlet

{

public void doGet(HttpServletRequest req,HttpServletResponse res)

throws ServletException, IOException

{

//setting the content type

res.setContentType("text/html");

//create the stream to write the data

PrintWriter pw=res.getWriter();

int N = Integer.parseInt(req.getParameter("Num"));

int f = 1;

//writing html in the stream

pw.println("<html><body>");

for(int i=1;i<=N;i++)

f = f*i;

pw.println("<H2>Factorial of "+N+" is "+ f +"</H2>");

pw.println("</body></html>");

//closing the stream

pw.close();

}

Servlet and request object

Simple program to display elements and values in request object

import javax.servlet.http.*;

import javax.servlet.*;

import java.io.*;

import java.util.*;

public class Req_parameters extends HttpServlet

{

public void doGet(HttpServletRequest req,HttpServletResponse res)

throws ServletException, IOException

{

//setting the content type

res.setContentType("text/html");

//create the stream to write the data

PrintWriter pw=res.getWriter();

String addr = req.getRemoteAddr();

String host = req.getRemoteHost();

String pl = req.getProtocol();

boolean sec = req.isSecure();

StringBuffer req_url = req.getRequestURL();

//writing html in the stream

pw.println("<html><body>");

pw.println("<h2>Client Address = "+addr+"</br>");

pw.println("Client Name = "+host+"</br>");

pw.println("Protocol = "+pl+"</br>");

pw.println("Security = "+sec+"</br>");

pw.println("Request URL = "+req_url+"</br>");

pw.println("</br>");

pw.println("Header Fields: </br></h2>");

pw.println("<h3>");

String HdrName, HdrVal;

Enumeration Hdr = req.getHeaderNames();

if(Hdr==null)

pw.println("Unable to access Header...</br>");

else

{

while(Hdr.hasMoreElements())

{

HdrName = (String)Hdr.nextElement();

HdrVal = req.getHeader(HdrName);

pw.println(HdrName + " : " + HdrVal + "</br>");

}

pw.println("</h3>");

pw.println("</body></html>");

//closing the stream

pw.close();

}

Form data and servlets

Simple program to demonstrate accessing a form data in a servlet

// Form to submit user name

<html>

<head>

<title>HTML Forms and Servlets</title>

<style>

label

{

font-family:vivaldi;

font-size:x-large;

letter-spacing:2px;

line-height:40px;

}

</style>

</head>

<body>

<h2>HTML and Servlets</h2></br>

<label>First Name </label>

</br> </br>

<button class="btn" type="button " >Click me!!! </button>

</center>

</form>

</body>

</html>

// Servlet to access form data and display a welcome message

import javax.servlet.http.*;

import javax.servlet.*;

import java.io.*;

import java.util.*;

public class formdata extends HttpServlet

{

public void doGet(HttpServletRequest req,HttpServletResponse res)

throws ServletException, IOException

{

//setting the content type

res.setContentType("text/html");

//create the stream to write the data

PrintWriter pw=res.getWriter();

String N = (String)req.getParameter("UsrName");

//writing html in the stream

pw.println("<html><body>");

if(N.length()==0)

pw.println("<H2>Welcome Guest.</H2>");

else

pw.println("<H2>Welcome "+N+".</H2>");

pw.println("</body></html>");

//closing the stream

pw.close();

}

Hit Counter

Simple program to demonstrate accessing a servlet in Apache Tomcat Server

Hit counter program

import javax.servlet.http.*;

import javax.servlet.*;

import java.io.*;

public class HitCounter extends HttpServlet

{

private int counter = 0;

public void doGet(HttpServletRequest req,HttpServletResponse res)

throws ServletException, IOException

{

//setting the content type

res.setContentType("text/html");

//create the stream to write the data

PrintWriter pw=res.getWriter();

counter++;

//writing html in the stream

pw.println("<html><body>");

pw.println("<h2>Hit Count = "+counter+"</h2>");

pw.println("</body></html>");

//closing the stream

pw.close();

}