汉字验证码
有时在注册论坛会员时，网页中的验证码是以汉字形式出现的。汉字验证码技术比字母和数字混合验证码技术更先进。通过汉字验证码，可以有效地防止非法用户灌水。本实例中主要通过生成的汉字区位码，将其转换成汉字。区位码是汉字一一对应的编码，用4位数字表示，前两位从01到94称为区码，后两位从01到94称为位码，一个汉字的前一半是ASC II码位“160+区码”的字符，后一半是ASC II码“160+位码”的字符。
今天把主要代码给贴出来供需要的朋友参考下：
在页面加载时调用相应的方法就可以了：
protected
void
Page_Load(
object
sender, EventArgs e)
{
GraphicsImage(
4
);
//
调用方法生成四位汉字验证码
}
private
void
GraphicsImage(
int
length)
{
System.Drawing.Bitmap image
=
new
System.Drawing.Bitmap((
int
)Math.Ceiling((GetString(length).Length
*
22.5
)),
22
);
Graphics g
=
Graphics.FromImage(image);
//
创建画布
try
{
//
生成随机生成器
Random random
=
new
Random();
//
清空图片背景色
g.Clear(Color.White);
//
画图片的背景噪音线
for
(
int
i
=
0
; i
<
1
; i
++
)
{
int
x1
=
random.Next(image.Width);
int
x2
=
random.Next(image.Width);
int
y1
=
random.Next(image.Height);
int
y2
=
random.Next(image.Height);
g.DrawLine(
new
Pen(Color.Black), x1, y1, x2, y2);
}
Font font
=
new
System.Drawing.Font(
"
Couriew New
"
,
12
, System.Drawing.FontStyle.Bold);
System.Drawing.Drawing2D.LinearGradientBrush brush
=
new
System.Drawing.Drawing2D.LinearGradientBrush
(
new
Rectangle(
0
,
0
, image.Width, image.Height), Color.Blue, Color.DarkRed,
1.2f
,
true
);
g.DrawString(GetString(length), font, brush,
2
,
2
);
//
画图片的前景噪音点
for
(
int
i
=
0
; i
<
50
; i
++
)
{
int
x
=
random.Next(image.Width);
int
y
=
random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
//
画图片的边框线
g.DrawRectangle(
new
Pen(Color.Silver),
0
,
0
, image.Width
-
1
, image.Height
-
1
);
System.IO.MemoryStream ms
=
new
System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType
=
"
image/Gif
"
;
Response.BinaryWrite(ms.ToArray());
}
catch
(Exception ms)
{
Response.Write(ms.Message);
}
}
private
string
GetString(
int
length)
{
Encoding gb
=
Encoding.GetEncoding(
"
gb2312
"
);
object
[] bytes
=
CreateString(length);
//
根据汉字字节解码出中文汉字
string
str1
=
gb.GetString((
byte
[])Convert.ChangeType(bytes[
0
],
typeof
(
byte
[])));
string
str2
=
gb.GetString((
byte
[])Convert.ChangeType(bytes[
1
],
typeof
(
byte
[])));
string
str3
=
gb.GetString((
byte
[])Convert.ChangeType(bytes[
2
],
typeof
(
byte
[])));
string
str4
=
gb.GetString((
byte
[])Convert.ChangeType(bytes[
3
],
typeof
(
byte
[])));
string
str
=
str1
+
str2
+
str3
+
str4;
Response.Cookies.Add(
new
HttpCookie(
"
CheckCode
"
, str));
return
str;
}
private
object
[] CreateString(
int
strlength)
{
//
定义一个数组存储汉字编码的组成元素
string
[] str
=
new
string
[
16
] {
"
0
"
,
"
1
"
,
"
2
"
,
"
3
"
,
"
4
"
,
"
5
"
,
"
6
"
,
"
7
"
,
"
8
"
,
"
9
"
,
"
a
"
,
"
b
"
,
"
c
"
,
"
d
"
,
"
e
"
,
"
f
"
};
Random ran
=
new
Random();
//
定义一个随机数对象
object
[] bytes
=
new
object
[strlength];
for
(
int
i
=
0
; i
<
strlength; i
++
)
{
//
获取区位码第一位
int
ran1
=
ran.Next(
11
,
14
);
string
str1
=
str[ran1].Trim();
//
获取区位码第二位并防止数据重复
ran
=
new
Random(ran1
*
unchecked
((
int
)DateTime.Now.Ticks)
+
i);
int
ran2;
if
(ran1
==
13
)
{
ran2
=
ran.Next(
0
,
7
);
}
else
{
ran2
=
ran.Next(
0
,
16
);
}
string
str2
=
str[ran2].Trim();
//
获取区位码第三位
ran
=
new
Random(ran2
*
unchecked
((
int
)DateTime.Now.Ticks)
+
i);
int
ran3
=
ran.Next(
10
,
16
);
string
str3
=
str[ran3].Trim();
//
获取区位码第四位
ran
=
new
Random(ran3
*
unchecked
((
int
)DateTime.Now.Ticks)
+
i);
int
ran4;
if
(ran3
==
10
)
{
ran4
=
ran.Next(
1
,
16
);
}
else
if
(ran3
==
15
)
{
ran4
=
ran.Next(
0
,
15
);
}
else
{
ran4
=
ran.Next(
0
,
16
);
}
string
str4
=
str[ran4].Trim();
//
定义字节变量存储产生的随机汉字区位码
byte
byte1
=
Convert.ToByte(str1
+
str2,
16
);
byte
byte2
=
Convert.ToByte(str3
+
str4,
16
);
byte
[] stradd
=
new
byte
[] { byte1, byte2 };
//
将产生的汉字字节放入数组
bytes.SetValue(stradd, i);
}
return
bytes;
}
以上就是生成汉字验证码的自定义方法。具体怎样在页面中使用可以QQ我