一、编写生成英文，数字和中文混合的彩色验证码的Servlet实现类
（1）创建名称为PictureCheckCode.java的Servlet。
public class PictureCheckCode extends HttpServlet {public PictureCheckCode() {super();}public void destroy() {super.destroy(); }public void init() throws ServletException {super.init();}public void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { }
}
(2)编写随机生成RGB颜色的方法getRandColor()
// 获取随机颜色public Color getRandColor(int s, int e) {Random random = new Random();if (s > 255) s = 255;if (e > 255) e = 255;int r = s + random.nextInt(e - s); //随机生成RGB颜色中的r值int g = s + random.nextInt(e - s); //随机生成RGB颜色中的g值int b = s + random.nextInt(e - s); //随机生成RGB颜色中的b值return new Color(r, g, b);}
（3）在Service()方法中编写生成彩色验证码的代码
public void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "No-cache");response.setDateHeader("Expires", 0);// 指定生成的响应是图片response.setContentType("image/jpeg");int width = 86;int height = 22;BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics();Graphics2D g2d = (Graphics2D) g;Random random = new Random();Font mFont = new Font("黑体", Font.BOLD, 17);g.setColor(getRandColor(200, 250));g.fillRect(0, 0, width, height);g.setFont(mFont);g.setColor(getRandColor(180, 200));// 画随机的线条for (int i = 0; i < 100; i++) {int x = random.nextInt(width - 1);int y = random.nextInt(height - 1);int x1 = random.nextInt(6) + 1;int y1 = random.nextInt(12) + 1;BasicStroke bs = new BasicStroke(2f, BasicStroke.CAP_BUTT,BasicStroke.JOIN_BEVEL);Line2D line = new Line2D.Double(x, y, x + x1, y + y1);g2d.setStroke(bs);g2d.draw(line);}String sRand = "";// 输出随机的验证文字String ctmp = "";int itmp = 0;for (int i = 0; i < 4; i++) {//random = new Random(new java.util.Date().getTime() + i);switch (random.nextInt(4)) {case 1:itmp = random.nextInt(26) + 65; // 生成A~Z的字母ctmp = String.valueOf((char) itmp);break;case 2: // 生成汉字String[] rBase = { "0", "1", "2", "3", "4", "5", "6", "7", "8","9", "a", "b", "c", "d", "e", "f" };// 生成第1位的区码int r1 = random.nextInt(3) + 11; //生成11到14之间的随机数String str_r1 = rBase[r1];// 生成第2位的区码int r2;if (r1 == 13) {r2 = random.nextInt(7); //生成0到7之间的随机数} else {r2 = random.nextInt(16); //生成0到16之间的随机数}String str_r2 = rBase[r2];// 生成第1位的位码int r3 = random.nextInt(6) + 10; //生成10到16之间的随机数String str_r3 = rBase[r3];// 生成第2位的位码int r4;if (r3 == 10) {r4 = random.nextInt(15) + 1; //生成1到16之间的随机数} else if (r3 == 15) {r4 = random.nextInt(15); //生成0到15之间的随机数} else {r4 = random.nextInt(16); //生成0到16之间的随机数}String str_r4 = rBase[r4];System.out.println(str_r1 + str_r2 + str_r3 + str_r4);// 将生成机内码转换为汉字byte[] bytes = new byte[2];//将生成的区码保存到字节数组的第1个元素中String str_r12 = str_r1 + str_r2;int tempLow = Integer.parseInt(str_r12, 16);bytes[0] = (byte) tempLow;//将生成的位码保存到字节数组的第2个元素中String str_r34 = str_r3 + str_r4;int tempHigh = Integer.parseInt(str_r34, 16);bytes[1] = (byte) tempHigh;ctmp = new String(bytes); //根据字节数组生成汉字//System.out.println("生成汉字:" + ctmp);break;default:itmp = random.nextInt(10) + 48; // 生成0~9的数字ctmp = String.valueOf((char) itmp);break;}sRand += ctmp;Color color = new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110));g.setColor(color);/** **随机缩放文字并将文字旋转指定角度* */// 将文字旋转指定角度Graphics2D g2d_word = (Graphics2D) g;AffineTransform trans = new AffineTransform();trans.rotate(random.nextInt(45) * 3.14 / 180, 15 * i + 8, 7);// 缩放文字float scaleSize = random.nextFloat() +0.8f;if (scaleSize > 1f) scaleSize = 1f;trans.scale(scaleSize, scaleSize);g2d_word.setTransform(trans);/** ********************* */g.drawString(ctmp, 15 * i + 18, 14);}// 将生成的验证码保存到Session中HttpSession session = request.getSession(true);session.setAttribute("randCheckCode", sRand);g.dispose();ImageIO.write(image, "JPEG", response.getOutputStream());}
二、配置servlet
<servlet><description>This is the description of my J2EE component</description><display-name>This is the display name of my J2EE component</display-name><servlet-name>PictureCheckCode</servlet-name><servlet-class>com.PictureCheckCode</servlet-class></servlet><servlet-mapping><servlet-name>PictureCheckCode</servlet-name><url-pattern>/PictureCheckCode</url-pattern></servlet-mapping>
