Create captcha image in java with value - by Dustbiin

Captcha is use for human validation and you can make an costume captcha image in java-

Example:

import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

public class Captcha
    extends HttpServlet
{
    private static final long   serialVersionUID  = -4687606895768367L;
    private int                 height            = 0;
    private int                 width             = 0;
    public static final String  CAPTCHA_KEY       = "captcha_key_name";
    private String              severIP           = null;

    public void init( ServletConfig config )
        throws ServletException
    {
        super.init( config );
        height = Integer.parseInt( getServletConfig().getInitParameter( "height" ) );
        width = Integer.parseInt( getServletConfig().getInitParameter( "width" ) );
    }

    protected void doGet( HttpServletRequest req, HttpServletResponse response )
        throws IOException, ServletException
    {
        //Expire response
        response.setHeader( "Cache-Control", "no-cache" );
        response.setDateHeader( "Expires", 0 );
        response.setHeader( "Pragma", "no-cache" );
        response.setDateHeader( "Max-Age", 0 );
        BufferedImage image = new BufferedImage( width, height, BufferedImage.TYPE_INT_RGB );
        Graphics2D graphics2D = image.createGraphics();
        Random r = new Random();
        int ch = 0;
        int x = r.nextInt(32) ;
        int y = r.nextInt(32);
        ch = x+y;
        String drawCh = x + " + " + y ;
        Color c = new Color( 228, 0 , 0 );
        Color c1 = new Color(237, 239, 241);
        GradientPaint gp = new GradientPaint( 30, 30, c, 15, 25, Color.GRAY, true );
        //set background color
        graphics2D.setColor( c1 );
        //fill background color
        graphics2D.fillRect(0, 0, width, height);
        graphics2D.setPaint( gp );
        Font font = new Font( "opensans_regular", Font.BOLD,13 );
        graphics2D.setFont( font );
        graphics2D.drawString( drawCh,5,21);
        graphics2D.dispose();
        HttpSession session = req.getSession( true );
        session.setAttribute( CAPTCHA_KEY, ch );
        OutputStream outputStream = response.getOutputStream();
        ImageIO.write( image, "jpeg", outputStream );
        outputStream.close();
    }   
}