select 인증번호 방식

package com.zyen.servlet;


import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
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;


/**
 *         
 * 
 * @author zyen
 * 
 */
public class RandCodeImageServlet extends HttpServlet {
    private static final long serialVersionUID = -1257947018545327308L;
    private static final String SESSION_KEY_OF_RAND_CODE = "randCode"; // todo      
    
    //private static final int count = 200;//     
    private static final int width = 73;//      
	private static final int height = 21;//      
	//private Font mFont = new Font("Arial Black", Font.PLAIN, 15); //    
	//private static final int lineWidth = 2;//      =1.414*lineWidth
	
	
	//  get post
	@Override
	public void service(final HttpServletRequest request,final HttpServletResponse response) 
			throws ServletException,IOException {
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);

		//int width = 60;
		//int height = 20;
		BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);

		Graphics g = image.getGraphics();
		Random random = new Random();

		g.setColor(getRandColor(200, 250));
		g.fillRect(0, 0, width, height);

		g.setFont(new Font("Times New Roman", Font.PLAIN, 20));

		g.setColor(getRandColor(160, 200));
		for (int i = 0; i < 155; i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			g.drawLine(x, y, x + xl, y + yl);
		}

		String sRand = "";
		for (int i = 0; i < 4; i++) {
			String rand = String.valueOf(random.nextInt(10));
			sRand += rand;

			g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
			//g.drawString(rand, 13 * i + 6, 16);
			g.drawString(rand, 15 * i + 8, 16);
		}
		//session
		request.getSession().setAttribute(SESSION_KEY_OF_RAND_CODE,sRand); 
		g.dispose();
		ImageIO.write(image, "JPEG", response.getOutputStream());
	}

	
	/**
	 *   ： 
	 * @param fc   ：
	 * @param bc   ： 
	 * @return   ：
	 */
	private Color getRandColor(int fc, int bc) { //           
		final Random random = new Random();
		if (fc > 255) {
			fc = 255;
		}
		if (bc > 255) {
			bc = 255;
		}
		final int r = fc + random.nextInt(bc - fc);
		final int g = fc + random.nextInt(bc - fc);
		final int b = fc + random.nextInt(bc - fc);

		return new Color(r, g, b);
	}


}

	
	
		RandCodeImage
		com.zyen.servlet.RandCodeImageServlet
	
	
		RandCodeImage
		/randCodeImage