<%@pagecontentType="image/jpeg"import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*"%>
<%!
ColorgetRandColor(intfc,intbc){//给定范围获得随机颜色
Randomrandom=newRandom();
if(fc>255)fc=255;
if(bc>255)bc=255;
intr=fc+random.nextInt(bc-fc);
intg=fc+random.nextInt(bc-fc);
intb=fc+random.nextInt(bc-fc);
returnnewColor(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
intwidth=60,height=20;
BufferedImageimage=newBufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取图形上下文
Graphicsg=image.getGraphics();
//生成随机类
Randomrandom=newRandom();
//设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0,0,width,height);
//设定字体
g.setFont(newFont("TimesNewRoman",Font.PLAIN,18));
//画边框
//g.setColor(newColor());
//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(inti=0;i<155;i++)
{
intx=random.nextInt(width);
inty=random.nextInt(height);
intxl=random.nextInt(12);
intyl=random.nextInt(12);
g.drawLine(x,y,x+xl,y+yl);
}
//取随机产生的认证码(4位数字)
//Stringrand=request.getParameter("rand");
//rand=rand.substring(0,rand.indexOf("."));
StringsRand="";
for(inti=0;i<4;i++){
Stringrand=String.valueOf(random.nextInt(10));
sRand+=rand;
//将认证码显示到图象中
g.setColor(newColor(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());
out.clear();
out=pageContext.pushBody();
%>
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