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java随机产生验证码，可以随机生成数字、大写字母、小写字母。还可以随机生成文字字体、及大小。在图片上面可能字体都不不同、大小不等。package com.hoo.util;import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.util.Random;import javax.imageio.ImageIO; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * <b>function:</b> 验证码生成工具类 * @project NetWorkService * @package com.hoo.util * @fileName ValidCodeUtils.java * @createDate 2010-8-3 下午03:05:50 * @author hoojo */ @SuppressWarnings(“unused”) public class ValidCodeUtils { /********************************************************************* * 验证码宽度 WIDTH = 60; /*** * 验证码高度 HEIGHT = 20;/********************************************************************** * 验证码背景颜色COLOR_FC_BG 应当小于COLOR_BC_BG COLOR_FC_BG = 200; /*** * 验证码背景颜色COLOR_FC_BG 应当小于COLOR_BC_BG COLOR_BC_BG = 250;/********************************************************************** * 验证码背景干扰线颜色COLOR_FC_LINE 应当小于COLOR_BC_LINE COLOR_FC_LINE = 160; /*** * 验证码背景干扰线颜色COLOR_FC_LINE 应当小于COLOR_BC_LINE COLOR_BC_LINE = 200;/*************************************************************************** * 验证码颜色COLOR_FC_CODE 应当小于COLOR_BC_CODE COLOR_FC_CODE = 20; /*** * 验证码颜色COLOR_FC_CODE 应当小于COLOR_BC_CODE COLOR_BC_CODE = 170;/*************************************************************************** * 生成在指定范围内的颜色 * @param fc 范围fc color值 小于255 * @param bc 范围bc color值 小于255 * @return Color Color getRandColor(int fc, int bc) {Random random = new Random();if (fc < 0)fc = 0;if (bc < 0)bc = 1;if (fc > 255)fc = 255;if (bc > 255)bc = 255;if (bc == fc)bc += 10;int temp = 0;if (bc < fc) {temp = bc;bc = fc;fc = temp;}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); }/** * <b>function:</b> 生成图片方法 * @createDate 2010-8-3 下午03:06:22 * @author hoojo * @param request HttpServletRequest * @param response HttpServletResponse * @return boolean * @throws Exception getImage(HttpServletRequest request, HttpServletResponse response) throws Exception{response.reset();response.setContentType(“image/jpeg”);// 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(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);// 获取图形上下文 Graphics img = image.getGraphics();// 生成随机类 Random random = new Random();// 设定背景色 img.setColor(getRandColor(COLOR_FC_BG, COLOR_BC_BG));img.fillRect(0, 0, WIDTH, HEIGHT);// 设定字体 img.setFont(new Font(“Times New Roman”, Font.PLAIN, 18));// 画边框// g.setColor(new Color());// g.drawRect(0,0,width-1,height-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 img.setColor(getRandColor(COLOR_FC_LINE, COLOR_BC_LINE));for (int i = 0; i < 155; i++) {int x = random.nextInt(WIDTH);int y = random.nextInt(HEIGHT);int xl = random.nextInt(12);int yl = random.nextInt(12);img.drawLine(x, y, x + xl, y + yl);}// 取随机产生的认证码(4位数字) String codeValue = “”;for (int i = 0; i < 4; i++) {//String rand = String.valueOf(random.nextInt(10)); String rand = getRandomChar();codeValue = codeValue.concat(rand);img.setFont(getRandomFont());//随机字体// 将认证码显示到图象中 img.setColor(getRandColor(COLOR_FC_CODE, COLOR_BC_CODE));img.drawString(rand, 13 * i + 6, 16);}request.getSession().setAttribute(“codeValue”, codeValue);// 图象生效 img.dispose();ImageIO.write(image, “JPEG”, response.getOutputStream()); }/** * 随机生成字符，网站空间，香港虚拟主机，含大写、小写、数字 * <b>function:</b> 功能 * @createDate 2010-8-23 上午10:33:55 * @author hoojo * String getRandomChar() {int index = (int) Math.round(Math.random() * 2);String randChar = “”;switch (index) {case 0://大写字符 randChar = String.valueOf((char)Math.round(Math.random() * 25 + 65));break;case 1://小写字符 randChar = String.valueOf((char)Math.round(Math.random() * 25 + 97));break;default://数字 randChar = String.valueOf(Math.round(Math.random() * 9));break;}return randChar; }/** * <b>function:</b> 随机生成字体、文字大小 * @createDate 2010-8-23 上午10:44:22 * @author hoojo * Font getRandomFont() {String[] fonts = {“Georgia”, “Verdana”, “Arial”, “Tahoma”, “Time News Roman”, “Courier New”, “Arial Black”, “Quantzite”};int fontIndex = (int)Math.round(Math.random() * (fonts.length – 1));int fontSize = (int) Math.round(Math.random() * 4 + 16);return new Font(fonts[fontIndex], Font.PLAIN, fontSize); } }其中验证码的值是保存在session中：request.getSession().setAttribute(“codeValue”, codeValue); 比较用户输入的值和session中的codeValue是否相等即可；下面是jsp页面调用servlet：ValidCodeServlet.javaValidCodeServlet中调用了上面的ValidCodeUtils 验证码生成工具类package com.hoo.servlet;import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse;import com.hoo.util.ValidCodeUtils;@SuppressWarnings(“serial”) public class ValidCodeServlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {try {ValidCodeUtils.getImage(request, response);} catch (Exception e) {e.printStackTrace();} }public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response); } }jsp页面调用servlet方法即可js：reloadValidCode方法function reloadValidCode(o) { o.src = “${pageContext.request.contextPath }/validCodeServlet?timed=” + new Date().getMilliseconds(); } 这里的”timed=” + new Date().getMilliseconds();是需要防止IE缓存用的html标签： <img src=”${pageContext.request.contextPath }/validCodeServlet” title=”看不清，点击刷新”/> 直接跟Servlet名称配置的url即可，和web.xml配置对应。主要调用路径${pageContext.request.contextPath }/validCodeServlet这样会带上根目录，比较保险。web.xml中validCodeServlet配置 <servlet> <servlet-name>validCodeServlet</servlet-name> <servlet-class>com.hoo.servlet.ValidCodeServlet</servlet-class> </servlet><servlet-mapping> <servlet-name>validCodeServlet</servlet-name> <url-pattern>/validCodeServlet</url-pattern> </servlet-mapping>
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