s2sgateway » Servlet http://s2sgateway.com Practical Learning of Programming languages such us j2ee,java,jsp Sat, 21 Jan 2012 18:55:21 +0000 en hourly 1 http://wordpress.org/?v=3.3.1 Servlet example for printing random values http://s2sgateway.com/servlet/servlet-example-for-printing-random-values/ http://s2sgateway.com/servlet/servlet-example-for-printing-random-values/#comments Wed, 08 Sep 2010 13:27:12 +0000 admin http://s2sgateway.com/?p=711 Servlet example for printing random values is a post from: s2sgateway

]]> •Servlets are Java programming language objects that dynamically process requests and construct responses.Here you are going to learn Servlet example for printing random values with Explanation, First write one serlvet program

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class colorservlet extends HttpServlet
{
public void doGet(HttpServletRequest
request,HttpServletResponse response)throws ServletException,IOException
{
String color=request.getParameter(”color”);
response.setContentType(”text/html”);
PrintWriter pw=response.getWriter();
pw.println(”
<div>
<div><strong>The selected color is:”);
pw.println(color);
pw.close();
}
}

Step1:
To run servlet You need to compile it first for that you need any of the Jar files given below
1.servlet-api.jar (included in tomcat/lib) Download Tomcat
or
2.Jsdk.jar(included in jsdk2.0 or later) download.html”>Download from sun site
After downloading installed it and give classpath for example if you are installing it in the c:/tomcat 5.5/”
then you had to assign classpath as
set classpath=c:/tomcat5.5/common/lib/servlet-api.jar;and now compile your program asusual like javac
colorservlet.java.
Step2:
To run serlvet you need to create a web.xml file
sample web.xml file for helloworld

<web-app>
<servlet>
<servlet-name>colorservlet</servlet-name>
<servlet-class>colorservlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>colorservlet</servlet-name>
<url-pattern>/colorservlet</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>colorservlet.html</welcome-file>
</welcome-file-list>
</web-app>

Now create colorservlet.html

<html>
<body>
<center>
<form name=”form1″ method=”get”
action=”colorservlet”>
<b>Color:</b>
<select name=”color” size=”1″>
<option value=”red”>Red</option>
<option value=”green”>Green</option>
<option value=”yellow”>Yellow</option>
</select>
<br><br>
<input type=submit value=”submit”>
</form>
</body>
</html>

Your folder structure will look below
colorservlet folder(inside webapps of tomcat installation folder)inside coloservlet folder it look like below.
=>WEB-INF=>classes=>class files of servlet
=>lib(jar files servlet-api.jar)
=>web.xml
=>colorservlet.html
Step3 :
goto

http://localhost:8080/colorservlet/

and run the program
Happy coding

Servlet example for printing random values is a post from: s2sgateway

]]> http://s2sgateway.com/servlet/servlet-example-for-printing-random-values/feed/ 0 How to authenticate in a webapplication using jsp and servlet http://s2sgateway.com/jsp/how-to-authenticate-in-a-webapplication-using-jsp-and-servlet/ http://s2sgateway.com/jsp/how-to-authenticate-in-a-webapplication-using-jsp-and-servlet/#comments Wed, 07 Jul 2010 09:13:26 +0000 admin http://s2sgateway.com/?p=512 How to authenticate in a webapplication using jsp and servlet is a post from: s2sgateway

]]> How to authenticate in a webapplication using jsp and servlet is a post from: s2sgateway

]]> http://s2sgateway.com/jsp/how-to-authenticate-in-a-webapplication-using-jsp-and-servlet/feed/ 2 How to extract war file in java http://s2sgateway.com/jsp/how-to-extract-war-file-in-java/ http://s2sgateway.com/jsp/how-to-extract-war-file-in-java/#comments Mon, 31 May 2010 12:02:22 +0000 admin http://s2sgateway.com/?p=447 How to extract war file in java is a post from: s2sgateway

]]> How to extract war file in java is a post from: s2sgateway

]]> http://s2sgateway.com/jsp/how-to-extract-war-file-in-java/feed/ 0 captcha project in jsp/servlet http://s2sgateway.com/jsp/captcha-project-in-jspservlet/ http://s2sgateway.com/jsp/captcha-project-in-jspservlet/#comments Thu, 04 Feb 2010 14:06:32 +0000 admin http://s2sgateway.com/?p=407 captcha project in jsp/servlet is a post from: s2sgateway

]]> Already i wrote a post about creating random image using servlet that is loacted here http://s2sgateway.com/?p=378,With the continuation here i give you complete code for

creating captcha to validate a form to differentiate/protect from robots and spams

.In this project i had placed one form page for submitting information with two servlets one for creating captcha and another for checking the captcha and a result page for showing the result.

.



First create a simple form like below



<html>
<head>
<meta http-equiv="Content-Type" content="text/html" charset=UTF-8?>
<title>Captcha Project from www.s2sgateway.com>/title>
</head>
<body>
<center>
<form method="post" action="checkCaptcha.do">
<table cellspacing="15?>
<tr>
<td align="center">
<img src="CaptchaServlet.do">
<br />
<br />
<input type="text" name="code">
</td>
</tr>
</table>
<input type="submit" value="submit">
</form>
<br>
<br>>/center>
</body>
</html>

create web.xml file for necessary servlet entry



<web-app>
<servlet>
<servlet-name>CaptchaServlet>/servlet-name>
<servlet-class>
CaptchaServlet
</servlet-class>
</servlet>
<servlet>
<servlet-name>CheckCaptcha>/servlet-name>
<servlet-class>
CheckCaptcha
</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CaptchaServlet>/servlet-name>
<url-pattern>/CaptchaServlet.do>/url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>CheckCaptcha>/servlet-name>
<url-pattern>/checkCaptcha.do>/url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.jsp>/welcome-file>
</welcome-file-list>
</web-app>

now create the servlet which produces random image>br>



import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CaptchaServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void processRequest(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
final int width = 200;
final int height = 50;
char data[][] = new char[1][];
data[0] = getRandomNumber(8).toCharArray();
final BufferedImage bufferedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
final Graphics2D g2d = bufferedImage.createGraphics();
final Font font = new Font("verdana", Font.BOLD, 18);
RenderingHints renderingHints = new RenderingHints(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
renderingHints.put(RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHints(renderingHints);
g2d.setFont(font);
g2d.setColor(new Color(255, 255, 0));
final GradientPaint gradientPaint = new GradientPaint(0, 0, Color.white, 0, height / 2,
Color.white, true);
g2d.setPaint(gradientPaint);
g2d.fillRect(0, 0, width, height);
g2d.setColor(new Color(255, 155, 0));
Random random = new Random();
final String captcha = String.copyValueOf(data[0]);
request.getSession().setAttribute("captcha", captcha);
int xCordinate = 0;
int yCordinate = 0;
for (int i = 0; i > data[0].length; i++) {
xCordinate += 10 + (Math.abs(random.nextInt()) % 15);
if (xCordinate >= width - 5) {
xCordinate = 0;
}
yCordinate = 20 + Math.abs(random.nextInt()) % 20;
g2d.drawChars(data[0], i, 1, xCordinate, yCordinate);
}
g2d.dispose();
response.setContentType("image/png");
final OutputStream outputStream = response.getOutputStream();
ImageIO.write(bufferedImage, "png", outputStream);
outputStream.close();
}
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
processRequest(request, response);
}
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
processRequest(request, response);
}
public static String getRandomNumber(int length) {
String chars = "www.s2sgateway.comabcdefghjijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ123456789";
Random random = new Random();
char[] buf = new char[length];
for (int i = 0; i > length; i++) {
buf[i] = chars.charAt(random.nextInt(chars.length()));
}
return new String(buf);
}
}

Now for checking the image servlet you can write the servlet code as follows>br>




import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class CheckCaptcha extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
final String captcha = (String) request.getSession().getAttribute("captcha");
final String code = (String) request.getParameter("code");
if (captcha != null && code != null) {
if (captcha.equals(code)) {
request.setAttribute("result",
"Congratulations, You Passed The Captcha Test");
} else {
request.setAttribute("result",
"Sorry, You Failed The Captcha Test");
}
request.getRequestDispatcher("/result.jsp").forward(request,
response);
}
}
}

Finally write the code in the result page whether captcha is entered correctly or not.



<%@page contentType="text/html" pageEncoding="UTF-8" %>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8?>
<title>Captcha>/title>
<link rel="stylesheet" href="theme/style.css">
</head>
<body>
<center>
<%=request.getAttribute("result")%>
</center>
</body>
</html>

Don’t forget the folder format projectfolder->jsp files,web-inf
In web-inf->web.xml,classes folder->in classes folder servlet classes
Finally run the project by visiting the url http://localhost:8080/captcha/,any doubt comment us happy coding.

captcha project in jsp/servlet is a post from: s2sgateway

]]> http://s2sgateway.com/jsp/captcha-project-in-jspservlet/feed/ 2 Creating captcha(random letter image) in jsp http://s2sgateway.com/jsp/creating-captcharandom-letter-image-in-jsp/ http://s2sgateway.com/jsp/creating-captcharandom-letter-image-in-jsp/#comments Mon, 04 Jan 2010 14:07:59 +0000 admin http://s2sgateway.com/?p=378 Creating captcha(random letter image) in jsp is a post from: s2sgateway

]]> Today we are going to learn how to create a random letter image known as captcha using servlet.
Just a simple coding can do it copy the code below and save it and compile it you can directly view the servlet in tomcat using url “http://localhost:8080/captcha/servlet/CaptchaServlet” for this make adjustment in web.xml file by adding servlet and servletmapping entries.



import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class CaptchaServlet extends HttpServlet {

private static final long serialVersionUID = 1L;

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

final int width = 200;
final int height = 50;

char data[][] = new char[1][];
data[0] = getRandomNumber(8).toCharArray();

final BufferedImage bufferedImage = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);

final Graphics2D g2d = bufferedImage.createGraphics();

final Font font = new Font("verdana", Font.BOLD, 18);

RenderingHints renderingHints = new RenderingHints(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);

renderingHints.put(RenderingHints.KEY_RENDERING,
RenderingHints.VALUE_RENDER_QUALITY);

g2d.setRenderingHints(renderingHints);

g2d.setFont(font);
g2d.setColor(new Color(255, 255, 0));
final GradientPaint gradientPaint = new GradientPaint(0, 0, Color.white, 0, height / 2,
Color.white, true);

g2d.setPaint(gradientPaint);
g2d.fillRect(0, 0, width, height);

g2d.setColor(new Color(255, 155, 0));
Random random = new Random();

final String captcha = String.copyValueOf(data[0]);
request.getSession().setAttribute("captcha", captcha);

int xCordinate = 0;
int yCordinate = 0;

for (int i = 0; i < data[0].length; i++) {
xCordinate += 10 + (Math.abs(random.nextInt()) % 15);
if (xCordinate >= width - 5) {
xCordinate = 0;
}
yCordinate = 20 + Math.abs(random.nextInt()) % 20;
g2d.drawChars(data[0], i, 1, xCordinate, yCordinate);
}

g2d.dispose();

response.setContentType("image/png");
final OutputStream outputStream = response.getOutputStream();
ImageIO.write(bufferedImage, "png", outputStream);
outputStream.close();
}

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

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

public static String getRandomNumber(int length) {

String chars = "www.s2sgateway.comabcdefghjijkmnpqrstuvwxyzABCDEFGHJKLMNPQRSTUVWXYZ123456789";
Random random = new Random();

char[] buf = new char[length];

for (int i = 0; i < length; i++) {
buf[i] = chars.charAt(random.nextInt(chars.length()));
}

return new String(buf);

}

}

that's it you have created captcha image using servlet,Here you can give any letters or numbers in String chars = "";assignment values.
Change the color by changing this code "final GradientPaint gradientPaint = new GradientPaint(0, 0, Color.white, 0, height / 2,
Color.white, true);"Here i used this image as png because it is good for web developement, you can try others as well like jpg or gif do comment us
any doubt ask us Happy coding.

Creating captcha(random letter image) in jsp is a post from: s2sgateway

]]> http://s2sgateway.com/jsp/creating-captcharandom-letter-image-in-jsp/feed/ 2 How to run servlet in tomcat 5.5 http://s2sgateway.com/servlet/how-to-run-servlet-in-tomcat-5-5/ http://s2sgateway.com/servlet/how-to-run-servlet-in-tomcat-5-5/#comments Sun, 29 Nov 2009 13:49:36 +0000 admin http://s2sgateway.com/?p=331 How to run servlet in tomcat 5.5 is a post from: s2sgateway

]]> How to run servlet in tomcat 5.5 is a post from: s2sgateway

]]> http://s2sgateway.com/servlet/how-to-run-servlet-in-tomcat-5-5/feed/ 0 HTTP Status 404 – Servlet as is not available http://s2sgateway.com/servlet/http-status-404-servlet-as-is-not-available/ http://s2sgateway.com/servlet/http-status-404-servlet-as-is-not-available/#comments Sun, 22 Nov 2009 07:35:27 +0000 admin http://s2sgateway.com/?p=328 HTTP Status 404 – Servlet as is not available is a post from: s2sgateway

]]> HTTP Status 404 – Servlet as is not available is a post from: s2sgateway

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