wǒ小Ъц傻

1.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());
%>
//调用页面
2.Test.jsp
<form name="form" method="post" action="Pass.jsp">
<input  name=rand type=text id="rand"  size="6" maxlength="4">
        <img src="image.jsp" width="60" height="20">
<input name="ok" type="submit" value=" 注 册 ">
</form>
//验证页面
3.Pass.jsp
<%@ page 
language="java"
contentType="text/html;charset=gb2312"
import = "java.util.*"
import = "java.sql.*"
import = "java.text.*" 
import = "java.io.*"
%>
 <%request.setCharacterEncoding("gb2312");%>
<%String rand = (String)session.getAttribute("rand");
     String input = request.getParameter("rand");
  if (rand.equals(input)) {
   out.println("ok!");
  }else{
out.println("wrong!");
}
%>