【原创】Strtus实现验证码
1.CheckCode 生成验证码类package com.zwj.tools;import javax.servlet.http.HttpServlet;import java.io.*;import javax.servlet.*;import javax.servlet.http.*;import java.awt.*;import java.awt.image.*;import javax.imageio.ImageIO;/** * 模块功能: 生成验证码 */@SuppressWarnings("serial")public class CheckCode extends HttpServlet {private static int WIDTH = 60;private static int HEIGHT = 25;public void doGet(HttpServletRequest request, HttpServletResponse response) {try {HttpSession session = request.getSession();response.setContentType("image/jpeg");ServletOutputStream sos = response.getOutputStream();// 设置浏览器不要缓存此图片response.setHeader("Pragma", "No-cache");response.setHeader("Cache-Control", "no-cache");response.setDateHeader("Expires", 0);// 创建内存图象并获得其图形上下文BufferedImage image = new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics();// 产生随机的认证码char[] rands = generateCheckCode();// 产生图像drawBackground(g);drawRands(g, rands);// 结束图像 的绘制 过程， 完成图像g.dispose();// 将图像输出到客户端ByteArrayOutputStream bos = new ByteArrayOutputStream();ImageIO.write(image, "JPEG", bos);byte[] buf = bos.toByteArray();response.setContentLength(buf.length);// 下面的语句也可写成： bos.writeTo(sos);sos.write(buf);bos.close();sos.close();// 将当前验证码存入到 Session 中session.setAttribute("check_code", new String(rands));// 直接使用下面的代码将有问题， Session 对象必须在提交响应前获得// request.getSession().setAttribute("check_code",new// String(rands));} catch (Exception e) {e.printStackTrace();}}/** * 定义验证码的字符表 ** @return */private char[] generateCheckCode() {String chars = "123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";char[] rands = new char;for (int i = 0; i < 4; i++) {int rand = (int) (Math.random() * 61);rands = chars.charAt(rand);}return rands;}/** * 划出随机数值 ** @param * @param rands */private void drawRands(Graphics g, char[] rands) {g.setColor(Color.BLUE);g.setFont(new Font(null, Font.PLAIN | Font.PLAIN, 18));g.drawString("" + rands, 1, 17);g.drawString("" + rands, 16, 15);g.drawString("" + rands, 31, 18);g.drawString("" + rands, 46, 16);// System.out.println(rands);}/** * 画图片背景 ** @param g */private void drawBackground(Graphics g) {g.setColor(new Color(0xDCDCDC));g.fillRect(0, 0, WIDTH, HEIGHT);// 随机产生 120 个干扰点for (int i = 0; i < 120; i++) {int x = (int) (Math.random() * WIDTH);int y = (int) (Math.random() * HEIGHT);int red = (int) (Math.random() * 255);int green = (int) (Math.random() * 255);int blue = (int) (Math.random() * 255);g.setColor(new Color(red, green, blue));g.drawOval(x, y, 1, 0);}}/** * 验证用户输入的验证码 ** @param request * @param response * @return */public static boolean checkLook(HttpServletRequest request,HttpServletResponse response, String check) {response.setContentType("text/html;charset=GB2312");try {// PrintWriter out = response.getWriter();HttpSession session = request.getSession(false);check = check.toLowerCase(); // 把用户输入的验证码转换成小写if (session == null)return false;String savedCode = (String) session.getAttribute("check_code");savedCode = savedCode.toLowerCase(); // 把存到session里的值转换成小写if (savedCode == null)return false;if (!savedCode.equals(check))return false;} catch (Exception e) {e.printStackTrace();}return true;}}2. 配置web.xml
<!-- 验证码 --> <servlet> <servlet-name>CheckCode</servlet-name> <servlet-class>com.zwj.tools.CheckCode</servlet-class> </servlet> <servlet-mapping> <servlet-name>CheckCode</servlet-name> <url-pattern>/CheckCode</url-pattern> </servlet-mapping>
3. 在action用调用验证码类
// 验证用户输入的验证码if (CheckCode.checkLook(request, response, validateChar)) { System.out.println("验证码成功！");/*** 当用户操作成功后，注意把session中的验证码清空: 这样可以防止用户不停的做某个操作. **/ request.getSession(false).removeAttribute("check_code");}else{ System.out.println("验证码错误！"); return mapping.getInputForward();}
4. jsp页面的显示
验证码：<img align="middle" src="CheckCode" />
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