s2sgateway » captcha creation 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 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