safecode.java

struts2 spring2.5 hibernate3.0 eclipse投票管理系统实例

package sunyang.vote.util;

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.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

@SuppressWarnings("serial")
public class SafeCode extends HttpServlet {
	public SafeCode() {
	}

	public void init() throws ServletException {
		super.init();
	}

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("image/jpeg");
		response.setHeader("Cache-Control", "no-cache");
		response.setHeader("Pragma", "No-cache");
		response.setDateHeader("Expires", 0L);
		HttpSession session = request.getSession();
		int width = 60;
		int height = 20;
		BufferedImage image = new BufferedImage(width, height, 1);
		Graphics g = image.getGraphics();
		Random random = new Random();
		g.setColor(getRandColor(200, 250));
		g.fillRect(0, 0, width, height);
		g.setFont(new Font("Arial", 0, 19));
		g.setColor(getRandColor(160, 200));
		for (int i = 0; i < 155; i++) {
			int x = random.nextInt(width + 100);
			int y = random.nextInt(height + 100);
			int xl = random.nextInt(10);
			int yl = random.nextInt(12);
			g.drawOval(x, y, x + xl, y + yl);
		}

		String sRand = "";
		for (int i = 0; i < 4; i++) {
			String rand = getRandChar(random.nextInt(36));
			sRand = 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);
		}

		session.setAttribute("rand", sRand);
		g.dispose();
		javax.servlet.ServletOutputStream imageOut = response.getOutputStream();
		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(imageOut);
		encoder.encode(image);
	}

	public void destroy() {
	}

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

	private String getRandChar(int randNumber) {
		return CHARARRAY[randNumber];
	}

	//private static final String CONTENT_TYPE = "image/jpeg";
	private static final String CHARARRAY[] = { "0", "1", "2", "3", "4", "5",
			"6", "7", "8", "9", "a", "b", "c", "d", "e", "f", "g", "h", "i",
			"j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v",
			"w", "x", "y", "z" };

}