验证码工具类

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验证码

验证码实现流程图：

验证码工具类：

package cn.itsource._02_randomcode;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 java.util.UUID;import javax.imageio.ImageIO;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;/** *  验证码工具类 * */   public class RandomCodeUtil {private RandomCodeUtil(){}/** *   判断用户输入的验证码与session中的是否一致 *   codeName：表示session中存的验证码名称 * */public static Boolean equalsRandomCode(HttpServletRequest req,String codeName){String code = req.getParameter("code");String sessionCode = (String)req.getSession().getAttribute(codeName);//删除服务器中的session，删除了不占用内存req.getSession().removeAttribute(codeName);return code.equals(sessionCode);}/** *  生成验证码的方法 * */public static  void createRandomCode(HttpServletRequest req, HttpServletResponse resp,String codeName)throws IOException{//生成随机数String randomCode = UUID.randomUUID().toString().substring(0, 5);//把随机数放进Session中req.getSession().setAttribute(codeName, randomCode);//创建图片对象int width = 100;int height = 40;int imageType = BufferedImage.TYPE_INT_RGB;BufferedImage image = new BufferedImage(width, height, imageType);//画板Graphics g = image.getGraphics();g.setColor(Color.WHITE);//绘制一个实心的矩形g.fillRect(1, 1, width - 2, height - 2);//把随机数画进图片中g.setColor(Color.BLACK);//设置随机数的颜色Font font = new Font("宋体", Font.BOLD + Font.ITALIC, 20);g.setFont(font);//设置随机数的字体和大小g.drawString(randomCode, 10, 28);//干扰线g.setColor(Color.GRAY);Random r = new Random();for (int i = 0; i < 100; i++) {g.fillRect(r.nextInt(width), r.nextInt(height), 2, 2);}//关闭g.dispose();//把图片对象以流的方式保存出去ImageIO.write(image, "jpg", resp.getOutputStream());}}

调用验证码工具类：

package cn.itsource._02_randomcode;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 java.util.UUID;import javax.imageio.ImageIO;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/randomCode")public class RandomCodeServlet extends HttpServlet {private static final long serialVersionUID = 1L;protected void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {//调用验证码工具类RandomCodeUtil.createRandomCode(req, resp,"RANDOMCODE_IN_SESSION");}}

验证码的校验功能：

package cn.itsource._02_randomcode;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;@WebServlet("/login")public class LoginServlet extends HttpServlet{private static final long serialVersionUID = 1L;@Overrideprotected void service(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {req.setCharacterEncoding("UTF-8");/** *  1.从请求中拿到用户输入的验证码 *  2.从session中拿到真实的验证码 *  3.判断两个验证码是否相等 *  如果不相等（登录失败），返回登录页面 *    相等    正常执行代码 * *///String code = req.getParameter("code");//String sessionCode = (String)req.getSession().getAttribute("RANDOMCODE_IN_SESSION");////删除服务器中的session，删除了不占用内存//req.getSession().removeAttribute("RANDOMCODE_IN_SESSION");if(!RandomCodeUtil.equalsRandomCode(req,"RANDOMCODE_IN_SESSION")){//提示信息req.setAttribute("errorMsg", "您输入的验证码有误");req.getRequestDispatcher("/login.jsp").forward(req, resp);return;}System.out.println("正常执行代码");}}

login.jsp文件：

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>    <!DOCTYPE html><html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>登录</title><script type="text/javascript">//修改图片(修改之前需要先拿到这张图片)function changeImg(img){//console.debug(document.getElementById("myImg"));//如果请求相同，会找缓存中的数据，就不会重新发送 //每次请求产生不同的产生提交img.src = "/randomCode?code="+Math.random();}</script></head><body><span style="color:red;">${errorMsg}</span><form action="/login" method="post">姓名：<input type="text" name="username" /> <br />密码：<input type="password" name="password" /> <br />验证码:<input type="text" name="code" /> <img src="/randomCode" style="cursor:pointer;" title="点我替换.." onclick="changeImg(this)" /> <br /><input type="submit" value="登录" /></form></body></html>

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