目录：
1、验证码的工作原理：
2、Graphics类：
3、源代码：
4、运行结果：
1、验证码的工作原理：
答：（1）服务器端生成验证码——发送给客户端用户——在客户端显示——用户根据显示输入验证码——提交数据信息——服务器端进行对比验证——正确则通过验证，不正确则不通过验证
（2）验证码就是将一串随机产生的数字或符号，生成一幅图片，图片里加上一些干扰元素，由用户肉眼识别其中的验证码信息，然后输入表单提交网站验证，验证成功后才能使用某项功能。
2、Graphics类：
答：（1）Graphics类是所有图形上下文的抽象基类，允许应用程序在组件以及闭屏图像上进行绘制。
（2）常用方法：
①drawImage(Image img, int x, int y, ImageObserver observer) ：绘制指定图像中当前可用的图像。
②drawString(String str, int x, int y) ：使用此图形上下文的当前字体和颜色绘制由指定 string 给定的文本。
③setFont(Font font) ：将此图形上下文的字体设置为指定字体。
④setColor(Color c)：将此图形上下文的当前颜色设置为指定颜色。
⑤fillRect(int x, int y, int width, int height)：填充指定的矩形。
x：要填充矩形的 x 坐标。
y：要填充矩形的 y 坐标。
width：要填充矩形的宽度。
height：要填充矩形的高度。
⑥drawLine(int x1, int y1, int x2, int y2) ：在此图形上下文的坐标系中，使用当前颜色在点 (x1, y1) 和 (x2, y2) 之间画一条线。
x1：第一个点的 x 坐标。
y1：第一个点的 y 坐标。
x2：第二个点的 x 坐标。
y2：第二个点的 y 坐标。
⑦dispose() ：释放此图形的上下文以及它使用的所有系统资源。
3、源代码：
①CodeService.java接口
package com.remoa.code.service; public interface CodeService { public void changeYanzhengma()throws Throwable;//改变验证码 public String gainYanzhengma()throws Throwable;//获得验证码 } ②CodeServiceImp.java package com.remoa.code.service; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.File; import java.io.FileOutputStream; import java.util.Date; import java.util.Random; import javax.imageio.ImageIO; import org.springframework.stereotype.Service; @Service public class CodeServiceImp implements CodeService{ private String yanzhengma; public String getYanzhengma() { return yanzhengma; } public void setYanzhengma(String yanzhengma) { this.yanzhengma = yanzhengma; } @Override public void changeYanzhengma() throws Throwable { int width = 80;//宽 int height = 40;//高 int linesNumber = 8;//干扰线数量 BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics graphics = image.getGraphics(); //设置背景色为白色 graphics.setColor(Color.WHITE); //设置一个宽为80px，高为40px的矩形框 graphics.fillRect(0, 0, width, height); //设置字体为Arial，加粗，20px的大小 graphics.setFont(new Font("Arial", Font.BOLD, 20)); Date d = new Date(); System.out.println("时间为： " + d.getTime()); Random r = new Random(d.getTime()); //设置验证码内容 String base = "QWERTYUIOPLKJHGFDSAZXCVBNM1234567890"; System.out.print("验证码为："); StringBuffer sb = new StringBuffer(); for(int i = 0; i < 4; i++){ int number = r.nextInt(base.length()); int y = 15 + r.nextInt(20); Color c = new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)); graphics.setColor(c); String s = String.valueOf(base.charAt(number)); graphics.drawString(s, 5 + i * width / 4, y); sb.append(s); } this.setYanzhengma(sb.toString()); System.out.println(this.getYanzhengma()); System.out.println("颜色：" + graphics.getColor() + ", \n字体：" + graphics.getFont()); //设置干扰线 for(int i = 0; i < linesNumber; i++){ Color c = new Color(r.nextInt(255), r.nextInt(255), r.nextInt(255)); graphics.setColor(c); graphics.drawLine(r.nextInt(width), r.nextInt(height), r.nextInt(width), r.nextInt(height)); } graphics.dispose(); ImageIO.write(image, "JPG", new FileOutputStream(new File("D:/apps/yanzhengma.jpg"))); } @Override public String gainYanzhengma() throws Throwable { return this.getYanzhengma(); } } ③UserAction.java package com.remoa.user.action; import javax.servlet.http.HttpSession; import javax.validation.Valid; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.validation.BindingResult; import org.springframework.web.bind.annotation.ModelAttribute; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; import com.remoa.code.service.CodeService; import com.remoa.user.domain.UserVO; import com.remoa.user.domain.UserValidate; import com.remoa.user.service.UserService; @Controller @RequestMapping("/user") public class UserAction { @Autowired private UserService service; private UserVO user = new UserVO(); @Autowired private CodeService codeService; private String yanzhengma; public UserService getService() { return service; } public void setService(UserService service) { this.service = service; } public UserVO getUser() { return user; } public void setUser(UserVO user) { this.user = user; } public String getYanzhengma() { return yanzhengma; } public void setYanzhengma(String yanzhengma) { this.yanzhengma = yanzhengma; } public CodeService getCodeService() { return codeService; } public void setCodeService(CodeService codeService) { this.codeService = codeService; } @RequestMapping("toregister.action") public String toRegister(){ return "redirect:/user/changeyzm.action"; } @RequestMapping(value="doregister.action", method=RequestMethod.POST) public String register(@Valid @ModelAttribute("registerModel") UserValidate validate, BindingResult result, Model model, HttpSession session)throws Throwable{ System.out.println("----------------进入到完成注册操作的doregister.action了------------"); model.addAttribute("validate", validate); if(result.hasErrors()){ return "user/register"; }else{ String password = validate.getUserpassword(); String checkPassword = validate.getCheckpassword(); if(password.equals(checkPassword)){ user.setUserpassword(password); model.addAttribute("passwordNotMatch", null); }else{ model.addAttribute("passwordNotMatch", "两次密码输入不匹配"); return "user/register"; } String yanzhengma = validate.getYanzhengma().toUpperCase(); String checkYanzhengma = (String)session.getAttribute("checkYanzhengma"); if(yanzhengma.equals(checkYanzhengma)){ model.addAttribute("yanzhengmaNotMatch", null); }else{ model.addAttribute("yanzhengmaNotMatch", "验证码输入错误"); return "user/register"; } user.setUsermail(validate.getUsermail()); System.out.println(user); service.register(user); model.addAttribute("validate", null); return "redirect:/user/login.action"; } } @RequestMapping("changeyzm.action") public String demo(HttpSession session) throws Throwable{ codeService.changeYanzhengma(); this.yanzhengma = codeService.gainYanzhengma(); System.out.println("--------------进入到代表验证码changeyzm.action了----------" + this.yanzhengma); session.setAttribute("checkYanzhengma", this.yanzhengma); return "/user/register"; } } ④测试页面register.jsp <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@taglib prefix="form" uri="http://www.springframework.org/tags/form" %> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0" /> <script type="text/javascript" src="${path }/bootstrap/js/jquery.min.js" ></script> <script type="text/javascript" src="${path }/bootstrap/js/bootstrap.min.js" ></script> <link rel="stylesheet" href="${path }/bootstrap/css/bootstrap.min.css" /> <title>注册页面</title> <style> body { font-family: "Helvetica Neue", Helvetica, Arial, "Microsoft Yahei UI", "Microsoft YaHei", SimHei, "\5B8B\4F53", simsun, sans-serif; } .error{ color:red; } </style> </head> <body> <div class="col-md-7" style="text-align:center; font-size:25px"> 新用户注册: </div> <div class="col-md-7"> <form:form class="form" action="doregister.action" modelAttribute="registerModel" method="post" role="form" > <div class="form-group col-md-12"> <label for="usermail" class="col-md-2 control-label"> 邮箱： </label> <div class="col-md-7"> <input type="text" name="usermail" class="form-control" value="${validate.usermail }" placeholder="请输入邮箱地址" /> </div> <div class="col-md-3"> <form:errors path="usermail" class="error"></form:errors> </div> </div> <div class="form-group col-md-12"> <label for="userpassword" class="col-md-2 control-label"> 密码： </label> <div class="col-md-7"> <input type="password" name="userpassword" class="form-control" value="${validate.userpassword }" placeholder="设置您的登录密码" /> </div> <div class="col-md-3"> <form:errors path="userpassword" class="error"></form:errors> </div> </div> <div class="form-group col-md-12"> <label for="checkpassword" class="col-md-2 control-label"> 密码确认： </label> <div class="col-md-7"> <input type="password" name="checkpassword" class="form-control" value="${validate.checkpassword }" placeholder="请再次输入密码" /> </div> <div class="col-md-3"> <form:errors path="checkpassword" class="error"></form:errors> </div> </div> <div class="form-group col-md-12"> <label for="yanzhengma" class="col-md-2 control-label"> 验证码： </label> <div class="col-md-3"> <input type="text" name="yanzhengma" class="form-control" value="${validate.yanzhengma }" placeholder="请输入验证码"> </div> <div class="col-md-3"> <img src="/images/yanzhengma.jpg" alt="验证码"/> <a href="${path }/user/toregister.action">看不清</a> </div> <div class="col-md-4"> <form:errors path="yanzhengma" class="error"></form:errors> </div> </div> <input type="submit" class="btn btn-success col-md-offset-3" value="提交" /> <input type="reset" class="btn btn-primary col-md-offset-1" value="重置" /> <a href="${path }/user/login.action">点此返回登录界面</a> <p class="error">${passwordNotMatch }</p> <p class="error">${yanzhengmaNotMatch }</p> </form:form> </div> </body> </html> 4、运行结果： 图4.1 运行结果