进行一次性校验码的校验（session、时间戳、随机数、字符缓存、绘画）

来源：互联网发布：上海闵行奥特莱斯淘宝编辑：程序博客网时间：2024/06/03 14:53

<!DOCTYPE html><html><head><title>MyHtml.html</title><meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="this is my page"><meta http-equiv="content-type" content="text/html; charset=UTF-8"><!--<link rel="stylesheet" type="text/css" href="./styles.css">--><script type="text/javascript"> function changeimage(){ document.getElementById("imag").src="/J2EE/checkimagservlet?time="+new Date().getTime(); //由于没有改变路径，浏览器有缓存，自动加载缓存内的值,加上时间戳后每次路径不一样 } </script></head><body><form action="/J2EE/myhttpservlet" method="post">姓名 <input name="username" type="text"> 密码 <inputname="password" type="password"><div>验证码<input name="code" type="text"></div><div><img src="/J2EE/checkimagservlet" id="imag" onclick="changeimage()"></div><!-- //验证码生成的servlet --><input type="submit" name="提交"></form></body></html>

package javapack;import java.awt.Color;import java.awt.Font;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.IOException;import java.io.PrintWriter;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 checkimagservlet extends HttpServlet {/** *  */private static final long serialVersionUID = 1L;public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {int width=120;int height=30;//步骤一 绘制一张内存中的图片BufferedImage bi=new BufferedImage (width,height,BufferedImage.TYPE_INT_RGB);//表示一个图像，该图像具有整数像素的 8 位 RGB 颜色//步骤二 图片绘制背景颜色 ---通过绘图对象Graphics g=bi.getGraphics();//得到画图对象---画笔//绘制任何图形之前，都必须指定一个颜色g.setColor(getRandColor(200,250));g.fillRect(0, 0, width, height);//画填充矩形,前两个参数指的是矩形左上角的坐标，后两个参数是矩形的宽和高//步骤三 绘制边框g.setColor(Color.WHITE);g.drawRect(0, 0, width-1, height-1);//步骤四 四个随机数字Graphics2D g2=(Graphics2D) g;//设置输出字体g2.setFont(new Font("宋体",Font.BOLD,18));//参数为字体、风格、字号String words="ABCDEFGHIGKLMNOPQRSTUVWXYZ1234567890";Random random=new Random();//生成随机数//将生成的验证码保存到session中StringBuffer buffer=new StringBuffer();//定义X坐标int x=10;for(int i=0;i<4;i++){//随机颜色new corlor(r,g,b)g2.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//nextInt(n),生成一个0到n的数//旋转-30,---30度int jiaodu =random.nextInt(60)-30;//换算弧度double theta =jiaodu*Math.PI/180;//生成一个随机数字int index=random.nextInt(words.length());//从word中随便选取一个值//获得字母数字char c=words.charAt(index);//将生成的字加入到buffer中buffer.append(c);//将c输出到图片g2.rotate(theta, x, 20);g2.drawString(String.valueOf(c), x, 20);g2.rotate(-theta, x, 20);x+=30;}request.getSession().setAttribute("code", buffer.toString());//步骤五 绘制干扰线g.setColor(getRandColor(160,200));int x1;int x2;int y1;int y2;for(int i=0;i<30;i++){x1=random.nextInt(width);x2=random.nextInt(12);y1=random.nextInt(height);y2=random.nextInt(12);g.drawLine(x1, y1, x1+x2, y1+y2);}//将上面图片输出到浏览器g.dispose();//释放资源ImageIO.write(bi,"jpg",response.getOutputStream());}private Color getRandColor(int fc, int bc) {// TODO Auto-generated method stubRandom 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);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);}}

package javapack;import java.io.IOException;import java.io.PrintWriter;import java.sql.SQLException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class httpservlet extends HttpServlet {@Overridepublic void init() throws ServletException {// TODO Auto-generated method stub//初始化一个变量count值为0，用来记录登录的人数int count=0;//将这个值存入servletcontextthis.getServletContext().setAttribute("count", count);}public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html; charset=UTF-8");//解决向页面输出中文乱码,而且还可以写HTMLfinal long serialVersionUID=1L;//校验验证码String code1 = request.getParameter("code");String code2 = (String) request.getSession().getAttribute("code");request.getSession().removeAttribute("code");//清除sessionif(!code1.equalsIgnoreCase(code2))//忽略大小写{request.setAttribute("msg", "验证码输入错误");request.getRequestDispatcher("/html/login.jsp").forward(request,response);return;}//接收表单参数String username=request.getParameter("username");//通过input的name值获得输入的usernameString password=request.getParameter("password");//封装到实体对象User user=new User();user.setUsername(username);//将username与password封装到user对象中user.setPassword(password);//调用业务层处理数据userservice us=new userservice();try {User existuser=us.login(user);//将user传入到login方法判断用户是否在数据库中存在//根据处理结果显示信息（页面跳转）if(existuser==null){response.getWriter().println("<h1>登录失败</h1>");}else{//记录登录成功的人数int count=(Integer) this.getServletContext().getAttribute("count");count++;this.getServletContext().setAttribute("count", count);/*response.getWriter().println("<h1>登录成功，你好,"+existuser.getUsername()+"</h1></br>");response.getWriter().println("<h1>1s后页面跳转。。。。</h1>");response.setHeader("Refresh","1;url=/J2EE/countservlet");*//*response.setStatus(302);//状态码重定向response.setHeader("Location", "/J2EE/html/success.html");*/response.sendRedirect( "/J2EE/countservlet");return;}} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {doGet(request, response);//post方式和get方式执行同一方法}}

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