认证码输入页�?lt;/title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV="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> <td align=left>�pȝ��产生的认证码�Q?lt;/td> <td></td> </tr> <tr> <td align=left>输入上面的认证码�Q?lt;/td> <td><input type=text name=rand maxlength=4 value=""></td> </tr> <tr> <td colspan=2 align=center><input type=submit value="提交��?></td> </tr> </form> </body> </html> -----------------验证的页�?---------check.jsp <%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %> <html> <head> <title>认证码验证页�?lt;/title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV="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"); %> �pȝ��产生的认证码为： <%= rand %> 您输入的认证码�ؓ�Q?<%= input %> <% if (rand.equals(input)) { %> 输入相同�Q�认证成功！ <% } else { %> 输入不同�Q�认证失败！ <% } %> </body> </html> <div align=right><a style="text-decoration:none;" href="http://www.aygfsteel.com/kylixlu/" target="_blank">陆昱�?/a> 2008-04-24 23:50 <a href="http://www.aygfsteel.com/kylixlu/archive/2008/04/24/195762.html#Feedback" target="_blank" style="text-decoration:none;">发表评论</a></div> </article> </main></body></html>

Thu, 24 Apr 2008 15:50:00 GMT

生成�?个随机数字和杂�ؕ背景的图片，数字和背景颜色会改变�Q�服务器端刷斎ͼ�用history.go(-1)也会变）
原型参考ALIBABA http://china.alibaba.com/member/showimage
产生验证码图片的文�g-----image.jsp

<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
 <%!
 Color getRandColor(int fc,int bc){//�l�定范围获得随机颜色
 Random 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);
 }
 %>
 <%
 //讄��面不缓�?br /> response.setHeader("Pragma","No-cache");
 response.setHeader("Cache-Control","no-cache");
 response.setDateHeader("Expires", 0);

    // 在内存中创徏图象
    int width=60, height=20;
    BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

// 获取囑�Ş上下�?br /> Graphics g = image.getGraphics();

//生成随机�c?br /> Random random = new Random();

// 讑֮�背景�?br /> g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);

//讑֮�字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));

//画边�?br /> //g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);

// 随机产生155条干扰线�Q��图象中的认证码不易被其它�E�序探测�?br /> g.setColor(getRandColor(160,200));
 for (int i=0;i<155;i++)
 {
 int x = random.nextInt(width);
 int y = random.nextInt(height);
 int xl = random.nextInt(12);
 int yl = random.nextInt(12);
 g.drawLine(x,y,x+xl,y+yl);
 }

// 取随��Z�生的认证�?4位数�?
 String sRand="";
 for (int i=0;i<4;i++){
 String rand=String.valueOf(random.nextInt(10));
 sRand+=rand;
 // ��认证码昄��到图象中
 g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));//调用函数出来的颜色相同，可能是因为种子太接近�Q�所以只能直接生�?br /> g.drawString(rand,13*i+6,16);
 }

// ��认证码存入SESSION
session.setAttribute("rand",sRand);

// 图象生效
g.dispose();

// 输出图象到页�?br /> ImageIO.write(image, "JPEG", response.getOutputStream());

---------------使用验证码图片的文�g---------a.jsp------------------------------------

<%@ page contentType="text/html;charset=gb2312" %>



 认证码输入页�?lt;/title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV="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> <td align=left>�pȝ��产生的认证码�Q?lt;/td> <td></td> </tr> <tr> <td align=left>输入上面的认证码�Q?lt;/td> <td><input type=text name=rand maxlength=4 value=""></td> </tr> <tr> <td colspan=2 align=center><input type=submit value="提交��?></td> </tr> </form> </body> </html> -----------------验证的页�?---------check.jsp <%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %> <html> <head> <title>认证码验证页�?lt;/title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV="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"); %> �pȝ��产生的认证码为： <%= rand %> 您输入的认证码�ؓ�Q?<%= input %> <% if (rand.equals(input)) { %> 输入相同�Q�认证成功！ <% } else { %> 输入不同�Q�认证失败！ <% } %> </body> </html> <div align=right><a style="text-decoration:none;" href="http://www.aygfsteel.com/kylixlu/" target="_blank">陆昱�?/a> 2008-04-24 23:50 <a href="http://www.aygfsteel.com/kylixlu/archive/2008/04/24/195762.html#Feedback" target="_blank" style="text-decoration:none;">发表评论</a></div> </article> </main></body></html>

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