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Posted on 2006-05-25 14:18 花 阅读(239) 评论(0) 编辑 收藏 所属分类: WEB Design
随机码的产生
<%
@ page contentType
=
"
image/jpeg
"
import
=
"
java.awt.*
"
%>
<%
@ page
import
=
"
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());
%>
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