1、书写验证码产生程序：package com.bobo.shopping.common.util;/*** <p>Title:用于产生校验码的servlet类</p>* <p>Description:用于产生校验码的servlet类</p>* @version 1.0*/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;public class CheckCodeServlet extends HttpServlet { private static final long serialVersionUID = 1L; private static int codeLength = 4; //验证码位数 private static int imageWidth = 60; //图片宽度private static int imageHeight = 20; //图片高度 public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //设置页面不缓存 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); // 在内存中创建图象 BufferedImage image = new BufferedImage(imageWidth, imageHeight, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); //生成随机类 Random random = new Random(); // 设定背景色 g.setColor(getRandColor(200, 250)); g.fillRect(0, 0, imageWidth, imageHeight); //设定字体 g.setFont(new Font("Times New Roman", Font.PLAIN, 18)); //画边框 g.setColor(new Color(20,20,20)); g.drawRect(0, 0, imageWidth - 1, imageHeight - 1); // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到 g.setColor(getRandColor(160, 200));for (int i = 0; i < 155; i++) { int x = random.nextInt(imageWidth); int y = random.nextInt(imageHeight);int xl = random.nextInt(12); int yl = random.nextInt(12);g.drawLine(x,y,x+xl,y+yl);}// 取随机产生的认证码// 可以自己设置数字字母等，本例只是产生数字String sRand = "";for (int i = 0;i < codeLength; i++) {String rand = String.valueOf(random.nextInt(10));sRand += rand;// 将认证码显示到图象中// 调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));g.drawString(rand, 13 * i + 6, 16); }// 将认证码存入SESSION中// 获取方式 request.getSession().getAttribute("checkCode");request.getSession().setAttribute("checkCode", sRand);// 图象生效g.dispose();// 输出图象到页面ImageIO.write(image, "JPEG", response.getOutputStream());}/** * 获取随机颜色* @param fc* @param bc* @return*/privateColor 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);}}
2、web.xml配置servlet<!-- 验证码servlet start --><servlet><servlet-name>checkCodeServlet</servlet-name><servlet-class>com.bobo.shopping.common.util.CheckCodeServlet</servlet-class></servlet><servlet-mapping><servlet-name>checkCodeServlet</servlet-name><url-pattern>/checkCode.jpg</url-pattern></servlet-mapping><!-- 校验码servlet end -->
3、jsp页面调用方法：<img src="<%=basePath%>checkCode.jpg"/>
4、提交后 后台获取本来产生验证码方法：request.getSession().getAttribute("checkCode");与提交的验证码进行比较即可。
