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JSP+servlet生成验证码并验证

發布時間：2025/3/20 javascript 64 豆豆

生活随笔收集整理的這篇文章主要介紹了 JSP+servlet生成验证码并验证小編覺得挺不錯的,現在分享給大家,幫大家做個參考.

生成驗證碼的基本過程是：

<%@ 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;BufferedImage image=new BufferedImage( width,height,BufferedImage.TYPE_INT_RGB);//由bufferdImage對象獲得畫筆gGraphics g=image.getGraphics();//畫筆填充矩形g.setColor(new Color(200,200,200));g.fillRect(0, 0, width, height);//生成隨機數Random rd=new Random();int rdNum=rd.nextInt(8999)+1000;String rdstr=String.valueOf(rdNum);//把隨機數放入session中session.setAttribute("rdStr", rdstr);//畫筆g畫隨機數g.setColor(Color.BLUE);g.setFont(new Font("",Font.PLAIN,20));g.drawString(rdstr, 10, 20);//這里的坐標是一個字符的左下角基線 //畫100個隨機點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的靜態函數write輸出圖像ImageIO.write(image, "JPEG", response.getOutputStream());out.clear();out=pageContext.popBody(); %>

畫圖的基本思想是：

<%@ 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"></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>歡迎登陸</b></h4><br> <table align="center" border="1"><tr><td align="right">請輸入賬號：</td><td><input name="zhanghao" type="text" > </td></tr><tr><td align="right">請輸入密碼：</td><td><input name="mima" type="password" size="21" > </td></tr><tr><td align="right">請輸入驗證碼：</td><td ><input name="yanzhengma" type="text" size="10" ><img name="imgcode" src="codes.jsp" onclick="refresh()"> </td></tr><tr><td></td><td><input type="submit" value="登錄" > <input type="button" value="忘記密碼？"></td></tr></table> </form></body> </html>

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 {//獲取表單的驗證碼String code=request.getParameter("yanzhengma");//獲取session中的驗證碼HttpSession session=request.getSession();String randstr=(String) session.getAttribute("rdStr");response.setCharacterEncoding("gb2312");//respons設為中文編碼PrintWriter out=response.getWriter();//獲得輸出寫出器if(code.equals(randstr)){//輸入的驗證碼和session保存的驗證碼相比較out.println("恭喜你，驗證碼正確！"); }else{ //response.sendRedirect("/code/back.jsp");out.println("驗證碼錯誤！！");} } }

輸入結果是：

總結

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