如何判段验证码是否正确？？
验证码的程序有了。。
就是不知道怎么判断
有代码就最好。
------解决方案--------------------
产生验证码图片的文件-----image.jsp
<%@ page contentType= "image/jpeg " import= "java.awt.*,java.awt.image.*,java.util.*,javax.imageio.* " %>
<%!
Color getRandColor(int fc,int bc){//给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);
}
%>
<%
//设置页面不缓存
response.setHeader( "Pragma ", "No-cache ");
response.setHeader( "Cache-Control ", "no-cache ");
response.setDateHeader( "Expires ", 0);
// 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();
//生成随机类
Random random = new Random();
// 设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font( "Times New Roman ",Font.PLAIN,18));
//画边框
//g.setColor(new Color());
//g.drawRect(0,0,width-1,height-1);
// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
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);
}
// 取随机产生的认证码(4位数字)
String sRand= " ";
for (int i=0;i <4;i++){
String rand=String.valueOf(random.nextInt(10));
sRand+=rand;
// 将认证码显示到图象中
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，所以只能直接生成
g.drawString(rand,13*i+6,16);
}
// 将认证码存入SESSION
session.setAttribute( "rand ",sRand);
// 图象生效
g.dispose();
// 输出图象到页面
ImageIO.write(image, "JPEG ", response.getOutputStream());
%>
---------------使用验证码图片的文件---------a.jsp------------------------------------
<%@ page contentType= "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= "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> 系统产生的认证码： </td>
<td> <img border=0 src= "image.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> <input type=submit value= "提交检测 "> </td>
</tr>
</form>
</body>
</html>
-----------------验证的页面----------check.jsp