jsp验证码代码

1、jsp验证码代码在开发中验证码是比较常用到有效防止这种问题对某一个特定注册用户用特定程序破解方式进行不断的登陆尝试的方式。此演示程序包括三个文件：code.jsp<%/ 在内存中创建图象int width=60, height=20;BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);/ 获取图形上下文Graphics g = image.getGraphics();/ 设定背景色g.setColor(new Color(0xDCDCDC);g.fillRect(0, 0, w

2、idth, height);/画边框g.setColor(Color.black);g.drawRect(0,0,width-1,height-1);/ 随机产生的认证码(4位数字)String rand =""+ (Math.random()*10000);rand = rand.substring(0,rand.indexOf(".");switch(rand.length()case 1: rand = "000"+rand; break;case 2: rand = "00"+rand; break;cas

3、e 3: rand = "0"+rand; break;default: rand = rand.substring(0,4); break;/ 将认证码存入SESSIONsession.setAttribute("rand",rand);/ 将认证码显示到图象中g.setColor(Color.black);Integer tempNumber = new Integer(rand);String numberStr = tempNumber.toString();g.setFont(new Font("Atlantic Inline&quo

4、t;,Font.PLAIN,18);String Str = numberStr.substring(0,1);g.drawString(Str,8,17);Str = numberStr.substring(1,2);g.drawString(Str,20,15);Str = numberStr.substring(2,3);g.drawString(Str,35,18);Str = numberStr.substring(3,4);g.drawString(Str,45,15);/ 随机产生88个干扰点，使图象中的认证码不易被其它程序探测到 Random random = new Rand

5、om();for (int i=0;i<20;i+)int x = random.nextInt(width);int y = random.nextInt(height);g.drawOval(x,y,0,0);/ 图象生效g.dispose();/ 输出图象到页面ImageIO.write(image, "JPEG", response.getOutputStream(); /在页面上调用 <img src="/yourPath/checkNum.jsp" />%>login.jsp程序代码 = <% page cont

6、entType="text/html;charset=gb2312" %><!DOCTYPE HTML PUBLIC "-/W3C/DTD HTML 4.01 Transitional/EN"> <html><head><title>认证码输入页面</title><meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV=

7、"Pragma" CONTENT="no-cache"><META HTTP-EQUIV="Cache-Control" CONTENT="no-cache"><META HTTP-EQUIV="Expires" CONTENT="0"></head><body><form method=post action="check.jsp"><table><tr><t

8、d align=left>系统产生的认证码：</td><td><img border=0 src="code.jsp"></td></tr><tr><td align=left>输入上面的认证码：</td><td><input type=text name=rand maxlength=4 value=""></td></tr><tr><td colspan=2 align=center&

9、gt;<input type=submit value="提交检测"></td> </tr></form></body></html>check.jsp程序代码 =<html><head><title>认证码验证页面</title><meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV

10、="Pragma" CONTENT="no-cache"><META HTTP-EQUIV="Cache-Control" CONTENT="no-cache"><META HTTP-EQUIV="Expires" CONTENT="0"></head><body><%String rand = (String)session.getAttribute("rand"); String input = request.getParameter("rand"); %>系统产生的认证码为： <%= rand %><br>您输入的认证码为： <%= input %><br><br><%if (rand