JSP实现验证码
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灯火互联
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 | 验证码的实现分为JSP页面和java类Servlet两部分： JSP页面： <!DOCTYPE html> <html> <head> <title>loginForm.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">--> </head> <body> <h3>带有验证码的登陆页面</h3> <form method="post" action="login.yan" > 用户名：<input type="text" name="usreName" size="10"><br><br/> 密 码：<input type="password" name="password" size="10"><br><br> 验证码：<input type="text" name="userNum" size="4"><img src="loginForm"/><br/><br/> <input type="submit" value="提交"> </form> </body> </html> java类： package com.csdn.session; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.image.BufferedImage; import java.io.ByteArrayOutputStream; import java.io.IOException; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.ServletOutputStream; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class loginForm extends HttpServlet { private static final long serialVersionUID = 1L; public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } private static int WIDTH = 80; private static int HEIGHT = 20; public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType("image/jpeg"); ServletOutputStream out=response.getOutputStream(); //PrintWriter out = response.getWriter(); response.setHeader("Pragma", "no-cache"); response.setHeader("Cache-Controll", "no-cache"); response.setIntHeader("Expires",0); //背景 BufferedImage bi = new BufferedImage(WIDTH, HEIGHT,BufferedImage.TYPE_INT_RGB); Graphics g = bi.getGraphics(); drawBackground(g); //随机产生验证码 char[] rands=generateCheckCode(); //System.out.println(fun(rands)); HttpSession session=request.getSession(); session.setAttribute("num",fun(rands)+"");//验证码==12-9=3；写入sesion对象 drawRands(g,rands); ByteArrayOutputStream bos=new ByteArrayOutputStream(); ImageIO.write(bi, "JPEG", bos); byte[] buf=bos.toByteArray();//将bi对象里面内容转化成字符 out.write(buf); response.setContentLength(buf.length); out.flush(); out.close(); } private int fun(char[] rands){ int num1=Integer.parseInt(rands[0]+"")*10+Integer.parseInt(rands[1]+""); int num2=Integer.parseInt(rands[2]+""); int num=0; if(rands[2]=='+'){ num=num1+num2; }else{ num=num1-num2; } return num; } private void drawRands(Graphics g, char[] rands) { g.setColor(Color.black); g.setFont(new Font(null,Font.ITALIC|Font.BOLD,18)); g.drawString(" "+rands[0],1,20); g.drawString(" "+rands[1],14,17); g.drawString(" "+rands[3],30,16); g.drawString(" "+rands[2],42,18); g.drawString(" "+rands[4],56,16); } private char[] generateCheckCode() { String chars="0123456789"; String char1="+-"; char[] rands=new char[5]; rands[0]=chars.charAt((int) (Math.random()*2)+1); rands[1]=chars.charAt((int) (Math.random()*10)); rands[2]=chars.charAt((int) (Math.random()*9)+1); rands[3]=char1.charAt((int) (Math.random()*2)); rands[4]='='; return rands; } private void drawBackground(Graphics g) { g.setColor(new Color(0XDCDCDC)); g.fillRect(0,0,WIDTH,HEIGHT); for(int i=0;i<20;i++){ int x=(int) (Math.random()*WIDTH); int y=(int) (Math.random()*HEIGHT); int red=(int) (Math.random()*255); int greed=(int) (Math.random()*255); int blue=(int) (Math.random()*255); g.setColor(new Color(red,greed,blue)); g.drawOval(x, y, 1, 0); } } } | |
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