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Posted on 2006-05-25 14:18 花 閱讀(249) 評論(0) 編輯 收藏 所屬分類: WEB Design
隨機(jī)碼的產(chǎn)生
<%
@?page?contentType?
=
?
"
?image/jpeg
"
?
import
=
"
java.awt.*?
"
?
%>
<%
@?page?
import
?
=
?
"
java.awt.image.*,java.util.*,javax.imageio.*
"
?
%>
<%!
 Color?getRandColor(
int
?fc,
int
?bc)
{
//
給定范圍獲得隨機(jī)顏色
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);
 }
%>
<%
//
設(shè)置頁面不緩存
response.setHeader(
"
Pragma
"
,
"
No-cache
"
);
response.setHeader(
"
Cache-Control
"
,
"
no-cache
"
);
response.setDateHeader(
"
Expires
"
,?
0
);
//
?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();
//
生成隨機(jī)類
Random?random?
=
?
new
?Random();
//
?設(shè)定背景色
g.setColor(getRandColor(
200
,
250
));
g.fillRect(
0
,?
0
,?width,?height);
//
設(shè)定字體
g.setFont(
new
?Font(
"
Times?New?Roman
"
,Font.PLAIN,
18
));
//
畫邊框
//
g.setColor(new?Color());
//
g.drawRect(0,0,width-1,height-1);
//
?隨機(jī)產(chǎn)生155條干擾線，使圖象中的認(rèn)證碼不易被其它程序探測到
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);
}
//
?取隨機(jī)產(chǎn)生的認(rèn)證碼(4位數(shù)字)
String?sRand
=
""
;
for
?(
int
?i
=
0
;i
<
4
;i
++
)
{
String?rand
=
String.valueOf(random.nextInt(
10
));
sRand
+=
rand;
//
?將認(rèn)證碼顯示到圖象中
g.setColor(
new
?Color(
20
+
random.nextInt(
110
),
20
+
random.nextInt(
110
),
20
+
random.nextInt(
110
)));
//
調(diào)用函數(shù)出來的顏色相同，可能是因?yàn)榉N子太接近，所以只能直接生成
g.drawString(rand,
13
*
i
+
6
,
16
);
}
//
?將認(rèn)證碼存入SESSION
session.setAttribute(
"
rand
"
,sRand);
//
?圖象生效
g.dispose();
//
?輸出圖象到頁面
ImageIO.write(image,?
"
JPEG
"
,?response.getOutputStream());
%>
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