<%@?page?contentType="image/jpeg"?import="java.awt.*,?
java.awt.image.*,java.util.*,javax.imageio.*"?%>?
<%?
//?在內(nèi)存中創(chuàng)建圖象?
int?width=60,?height=20;?
BufferedImage?image?=?new?BufferedImage(width,?height,?
BufferedImage.TYPE_INT_RGB);?

//?獲取圖形上下文?
Graphics?g?=?image.getGraphics();?

//?設(shè)定背景色?
g.setColor(new?Color(0xDCDCDC));?
g.fillRect(0,?0,?width,?height);?

//畫邊框?
g.setColor(Color.black);?
g.drawRect(0,0,width-1,height-1);?

//?取隨機產(chǎn)生的認(rèn)證碼(4位數(shù)字)?
String?rand?=?request.getParameter("rand");?
rand?=?rand.substring(0,rand.indexOf("."));?
switch(rand.length())?
{?
case?1:?rand?=?"000"+rand;?break;?
case?2:?rand?=?"00"+rand;?break;?
case?3:?rand?=?"0"+rand;?break;?
default:?rand?=?rand.substring(0,4);?break;?
}?

//?將認(rèn)證碼存入SESSION?
session.setAttribute("rand",rand);?

//?將認(rèn)證碼顯示到圖象中?
g.setColor(Color.black);?
Integer?tempNumber?=?new?Integer(rand);?
String?numberStr?=?tempNumber.toString();?

g.setFont(new?Font("Atlantic?Inline",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);?

//?隨機產(chǎn)生88個干擾點，使圖象中的認(rèn)證碼不易被其它程序探測到?
Random?random?=?new?Random();?
for?(int?i=0;i<20;i++)?
{?
int?x?=?random.nextInt(width);?
int?y?=?random.nextInt(height);?
g.drawOval(x,y,0,0);?
}?

//?圖象生效?
g.dispose();?

//?輸出圖象到頁面?
ImageIO.write(image,?"JPEG",?response.getOutputStream());?
%>

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