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JSP+servlet生成验证码并验证

发布时间：2025/3/20 javascript 80 豆豆
生活随笔 收集整理的这篇文章主要介绍了 JSP+servlet生成验证码并验证 小编觉得挺不错的,现在分享给大家,帮大家做个参考.



生成验证码的基本过程是：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@ page import="java.awt.*,java.awt.image.BufferedImage,javax.imageio.ImageIO" %><%response.setHeader("Cache-Control", "no-cache");int width=60,height=20;<!--实例化bufferdImage对象-->BufferedImage image=new BufferedImage( width,height,BufferedImage.TYPE_INT_RGB);//由bufferdImage对象获得画笔gGraphics g=image.getGraphics();//画笔填充矩形g.setColor(new Color(200,200,200));g.fillRect(0, 0, width, height);//生成随机数Random rd=new Random();int rdNum=rd.nextInt(8999)+1000;String rdstr=String.valueOf(rdNum);//把随机数放入session中session.setAttribute("rdStr", rdstr);//画笔g画随机数g.setColor(Color.BLUE);g.setFont(new Font("",Font.PLAIN,20));g.drawString(rdstr, 10, 20);//这里的坐标是一个字符的左下角基线 //画100个随机点g.setColor(Color.green);for(int i=0;i<100;i++){int x=rd.nextInt(width);int y=rd.nextInt(height);g.drawOval(x, y, 1, 1);}//用ImageIO的静态函数write输出图像ImageIO.write(image, "JPEG", response.getOutputStream());out.clear();out=pageContext.popBody(); %>

画图的基本思想是：

<!--loginform.jsp登录jsp--> <%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html><head><base href="<%=basePath%>"> <title>My JSP 'loginform.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">--></head> <body><script type="text/javascript">function refresh(){ document.loginform.imgcode.src="codes.jsp";}</script> <form name="loginform" action="/code/servlets/codeServlet" method="post"><h4 align="center"><b>欢迎登陆</b></h4><br> <table align="center" border="1"><tr><td align="right">请输入账号：</td><td><input name="zhanghao" type="text" > </td></tr><tr><td align="right">请输入密码：</td><td><input name="mima" type="password" size="21" > </td></tr><tr><td align="right">请输入验证码：</td><td ><input name="yanzhengma" type="text" size="10" ><img name="imgcode" src="codes.jsp" onclick="refresh()"> </td><!--验证码当图片处理，点击可刷新--></tr><tr><td></td><td><input type="submit" value="登录" > <input type="button" value="忘记密码？"></td></tr></table> </form></body> </html>

<!--codeServlet.java--> package servlets; import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class codeServlet extends HttpServlet {/*** The doPost method of the servlet. <br>** This method is called when a form has its tag value method equals to post.* * @param request the request send by the client to the server* @param response the response send by the server to the client* @throws ServletException if an error occurred* @throws IOException if an error occurred*/public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {//获取表单的验证码String code=request.getParameter("yanzhengma");//获取session中的验证码HttpSession session=request.getSession();String randstr=(String) session.getAttribute("rdStr");response.setCharacterEncoding("gb2312");//respons设为中文编码PrintWriter out=response.getWriter();//获得输出写出器if(code.equals(randstr)){//输入的验证码和session保存的验证码相比较out.println("恭喜你，验证码正确！"); }else{ //response.sendRedirect("/code/back.jsp");out.println("验证码错误！！");} } }

输入结果是：

总结

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