这篇文章会从前台页面到后台实现完整的讲解，下面跟着小编一起来看看。
1、前台的代码，image.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%><!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"><title>获取图片验证码</title><script type="text/javascript" src="${pageContext.request.contextPath }/static/js/jquery-1.10.2.min.js"></script></head><body> <form action="##" method='post'> <input type="hidden" id="userId" name="userId" value=""> <div> <div> <input type="text" name='loginName' id="loginName" placeholder="用户名" value="" class='form-control'/> </div> </div> <div> <div> <input type="password" autocomplete="off" id="pwd" name="pwd" placeholder="密码" class='form-control'/> </div> </div> <div> <div> <input id="validateCode" onblur="checkImg(this.value)" name="validateCode" type="text" placeholder="输入验证码"/> </div> <span><img id="codeValidateImg" onClick="javascript:flushValidateCode();"/></span> <p><a href="javascript:flushValidateCode();" >换一张</a></p> </div> <div> <span></span> </div> <div> <div> <input type="checkbox" name="remember" value="1" class='icheck-me' data-skin="square" data-color="blue" id="remember"> <label for="remember">记住我</label> </div> <input type="button" value="登录" onclick="javascript:submitForm();" class='btn btn-primary'> </div> </form><script type="text/javascript">$(document).ready(function() { flushValidateCode();//进入页面就刷新生成验证码 });/* 刷新生成验证码 */function flushValidateCode(){var validateImgObject = document.getElementById("codeValidateImg");validateImgObject.src = "${pageContext.request.contextPath }/getSysManageLoginCode?time=" + new Date();}/*校验验证码输入是否正确*/function checkImg(code){ var url = "${pageContext.request.contextPath}/checkimagecode"; $.get(url,{"validateCode":code},function(data){ if(data=="ok"){ alert("ok!") }else{ alert("error!") flushValidateCode(); } })}</script></body></html>2、后台代码ImageGenController.java
package com.dufyun.springmvc.web.controller;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.springframework.stereotype.Controller;import org.springframework.util.StringUtils;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import com.dufy.javaweb.test.RandomValidateCode;@Controllerpublic class ImageGenController { @RequestMapping(value="/toImg") public String toImg(){ return "image/image"; } //登录获取验证码 @RequestMapping("/getSysManageLoginCode") @ResponseBody public String getSysManageLoginCode(HttpServletResponse response, HttpServletRequest request) { response.setContentType("image/jpeg");// 设置相应类型,告诉浏览器输出的内容为图片 response.setHeader("Pragma", "No-cache");// 设置响应头信息，告诉浏览器不要缓存此内容 response.setHeader("Cache-Control", "no-cache"); response.setHeader("Set-Cookie", "name=value; HttpOnly");//设置HttpOnly属性,防止Xss攻击 response.setDateHeader("Expire", 0); RandomValidateCode randomValidateCode = new RandomValidateCode(); try { randomValidateCode.getRandcode(request, response,"imagecode");// 输出图片方法 } catch (Exception e) { e.printStackTrace(); } return ""; } //验证码验证 @RequestMapping(value = "/checkimagecode") @ResponseBody public String checkTcode(HttpServletRequest request,HttpServletResponse response) { String validateCode = request.getParameter("validateCode"); String code = null; //1:获取cookie里面的验证码信息 Cookie[] cookies = request.getCookies(); for (Cookie cookie : cookies) { if ("imagecode".equals(cookie.getName())) { code = cookie.getValue(); break; } } //1:获取session验证码的信息 //String code1 = (String) request.getSession().getAttribute(""); //2:判断验证码是否正确 if(!StringUtils.isEmpty(validateCode) && validateCode.equals(code)){ return "ok"; } return "error"; //这里我没有进行字母大小模糊的验证处理，感兴趣的你可以去试一下！ }}3、生成验证码的工具类RandomValidateCode.java
package com.dufy.javaweb.test;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.image.BufferedImage;import java.io.ByteArrayOutputStream;import java.util.Random;import javax.imageio.ImageIO;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class RandomValidateCode { private Random random = new Random(); private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";// 随机产生的字符串 private int width = 80;// 图片宽 private int height = 26;// 图片高 private int lineSize = 40;// 干扰线数量 private int stringNum = 4;// 随机产生字符数量 /* * 获得字体 */ private Font getFont() { return new Font("Fixedsys", Font.CENTER_BASELINE, 18); } /* * 获得颜色 */ private Color getRandColor(int fc, int bc) { if (fc > 255) fc = 255; if (bc > 255) bc = 255; int r = fc + random.nextInt(bc - fc - 16); int g = fc + random.nextInt(bc - fc - 14); int b = fc + random.nextInt(bc - fc - 18); return new Color(r, g, b); } /* * 绘制字符串 */ private String drowString(Graphics g, String randomString, int i) { g.setFont(getFont()); g.setColor(new Color(random.nextInt(101), random.nextInt(111), random .nextInt(121))); String rand = String.valueOf(getRandomString(random.nextInt(randString .length()))); randomString += rand; g.translate(random.nextInt(3), random.nextInt(3)); g.drawString(rand, 13 * i, 16); return randomString; } /* * 绘制干扰线 */ private void drowLine(Graphics g) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(13); int yl = random.nextInt(15); g.drawLine(x, y, x + xl, y + yl); } /* * 获取随机的字符 */ public String getRandomString(int num) { return String.valueOf(randString.charAt(num)); } /** * 生成随机图片 */ public void getRandcode(HttpServletRequest request,HttpServletResponse response,String key) { // BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类 BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_BGR); Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作 g.fillRect(0, 0, width, height); g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18)); g.setColor(getRandColor(110, 133)); // 绘制干扰线 for (int i = 0; i <= lineSize; i++) { drowLine(g); } // 绘制随机字符 String randomString = ""; for (int i = 1; i <= stringNum; i++) { randomString = drowString(g, randomString, i); } //1：将随机生成的验证码放入Cookie中 Cookie cookie = new Cookie(key,randomString); response.addCookie(cookie); //2：将随机生成的验证码放入session中 String sessionid = request.getSession().getId(); request.getSession().setAttribute(sessionid+key, randomString); System.out.println("*************" + randomString); //总结：这两种方式都是很好， //（1）：使用cookie的方式，将验证码发送到前台浏览器，不安全！不建议使用。 //（2）：使用session的方式，虽然能解决验证码不发送到浏览器，安全性较高了，但是如果用户量太大，这样的存储方式会对服务器造成压力，影响服务器的性能。不建议使用。 //这里暂时实现用这种方式，好的办法是，在项目中使用的缓存，将生成的验证码存放到缓存中，设置失效时间，这样既可以实现安全性也能减轻服务器的压力。 g.dispose(); try { ByteArrayOutputStream tmp = new ByteArrayOutputStream(); ImageIO.write(image, "png", tmp); tmp.close(); Integer contentLength = tmp.size(); response.setHeader("content-length", contentLength + ""); response.getOutputStream().write(tmp.toByteArray());// 将内存中的图片通过流动形式输出到客户端 } catch (Exception e) { e.printStackTrace(); }finally{ try { response.getOutputStream().flush(); response.getOutputStream().close(); } catch (Exception e2) { e2.printStackTrace(); } } }}4、总结
本文的内容到这就结束了，如果对里面的地方有不懂的地方，可以留言讨论。希望本文的内容对大家的学习工作能有所帮助。