Servlet验证码

package com.baiyang.lc.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.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.log4j.Logger;import com.sun.image.codec.jpeg.JPEGCodec;import com.sun.image.codec.jpeg.JPEGImageEncoder;/** * 验证码 */public class VerifyCodeServlet extends HttpServlet {private final Logger logger = Logger.getLogger(VerifyCodeServlet.class);private static final long serialVersionUID = 1L;/** * @see HttpServlet#HttpServlet() */public VerifyCodeServlet() {super();}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);}@Overrideprotected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);int width = 76, height = 34;BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);// 对访问的图片色调为RGB格式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.ROMAN_BASELINE, 25));g.setColor(getRandColor(160, 200));int lineNum = 0;while (lineNum < 100) {lineNum = random.nextInt(200);}for (int i = 0; i < lineNum; 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 = "";String chars = "1234567890QWERTYUIPLKJHGFDSAZXCVBNMqwertyuioplkjhgfdsazxcvbnm";for (int i = 0; i < 5; i++) {String rand = chars.charAt(random.nextInt(chars.length())) + "";sRand += rand;g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));g.drawString(rand, 13 * i + 5, 24);}request.getSession().setAttribute("verifyCode", sRand);logger.debug("验证码：" + sRand);g.dispose();JPEGImageEncoder encode = JPEGCodec.createJPEGEncoder(response.getOutputStream());encode.encode(image);}}