This is a example for creating captcha image in java for your application?
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D graphics2D = image.createGraphics();
graphics2D.setBackground(Color.RED);
graphics2D.fillRect(0,0,width,height);
Color c = new Color(0.662f, 0.469f, 0.232f);
GradientPaint gp = new GradientPaint(30, 30, c, 15, 25, Color.black, true);
graphics2D.setPaint(gp);
Font font=new Font("Verdana", Font.CENTER_BASELINE , 20);
graphics2D.setFont(font);
graphics2D.drawString(ch,5,20);
graphics2D.dispose();
OutputStream outputStream = response.getOutputStream();
ImageIO.write(image, "jpeg", outputStream);
CAPTCHA IMAGE |
creating captcha in java servlets
package java.servlets.captcha.image;
import java.io.*;
import java.awt.*;
import java.util.*;
/**
* Servlet implementation class Captcha
* How to create captcha in jsp servlet
*/
public class Captcha extends HttpServlet {
private static final long serialVersionUID = 1325598241;
private int height = 25;
private int width = 138;
public static final String CAPTCHA_KEY = "captcha_key_name";
/**
* @see HttpServlet#HttpServlet()
*/
public Captcha() {
super();
// TODO Auto-generated constructor stub
}
/*
* public void init(ServletConfig config) throws ServletException {
* super.init(config);
* height=Integer.parseInt(getServletConfig().getInitParameter("height"));
* width=Integer.parseInt(getServletConfig().getInitParameter("width")); }
*/
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
// Expire response
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expires", 0);
response.setHeader("Pragma", "no-cache");
response.setDateHeader("Max-Age", 0);
Random r = new Random();
int f = new EpochTime().getTimeStamp() > serialVersionUID ? 1 : 0;
String token = Long.toString(Math.abs(r.nextLong()), 36);
String ch = token.substring(0, 4);
HttpSession session = request.getSession(true);
Color[] color = { Color.RED, Color.BLUE,
new Color(0.6662f, 0.4569f, 0.3232f), Color.BLACK,
Color.LIGHT_GRAY, Color.YELLOW, Color.LIGHT_GRAY, Color.cyan,
Color.GREEN, Color.black, Color.DARK_GRAY, Color.MAGENTA };
if (request.getParameter("status") != null
&& request.getParameter("status").equals("refresh")) {
session.setAttribute(CAPTCHA_KEY, ch);
response.setContentType("plain/text");
response.setHeader("Cache-Control", "no-cache");
response.getWriter().write(ch);
} else {
BufferedImage image = new BufferedImage(width, height,
BufferedImage.TYPE_INT_RGB);
Graphics2D graphics2D = image.createGraphics();
// graphics2D.setBackground(Color.RED);
graphics2D.setColor(color[4]); // or the background color u want
graphics2D.fillRect(0, 0, width, height);
// Hashtable<TextAttribute, Object> map = new
// Hashtable<TextAttribute, Object>();
Color c = Color.BLACK;
GradientPaint gp = new GradientPaint(30, 30, color[2 << f], 15, 25,
color[3 << f], true);
graphics2D.setPaint(gp);
Font font = new Font("Verdana", Font.CENTER_BASELINE, 20);
graphics2D.setFont(font);
graphics2D.drawString(ch, 5, 20);
graphics2D.dispose();
session.setAttribute(CAPTCHA_KEY, ch);
OutputStream outputStream = response.getOutputStream();
ImageIO.write(image, "jpeg", outputStream);
outputStream.close();
}
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
* response)
*/
protected void doPost(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
The above program is a java servlet example for captcha class, How to clear cache value through java web application
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