C#版本的混合的验证码

<%@ Page Language="C#" ContentType="text/html" ResponseEncoding="utf-8" Debug="true" %>

<%@ import namespace="System"%>

<%@ import namespace="System.IO"%>

<%@ import namespace="System.Drawing"%>

<%@ import namespace="System.Drawing.Imaging"%>

<script runat="server">

private void Page_Load(object sender, System.EventArgs e){

ValidateCode( RndNum(6) );;//测试

}

private void ValidateCode(string VNum) {

Bitmap Img = null;

Graphics g = null ;

MemoryStream ms = null ;

int gheight = VNum.Length*12;

Img = new Bitmap(gheight,20);

g = Graphics.FromImage(Img);

Font f = new Font( "新宋体",12 );

SolidBrush s = new SolidBrush( Color.Red );

g.DrawString(VNum,f,s,3,3);

ms=new MemoryStream();

Img.Save(ms,ImageFormat.Png);

Response.ClearContent() ;//更改http ContentType

Response.ContentType="image/Png";

Response.BinaryWrite(ms.ToArray());

//回收资源

g.Dispose();

Img.Dispose();

Response.End();

}

private string RndNum(int VcodeNum) {

string Vchar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z" ;

string[] VcArray = Vchar.Split(',') ;

string VNum = "" ;//由于字符串很短，就不用StringBuilder了

int temp = -1 ;//记录上次随机数值，尽量避免生产几个一样的随机数

//采用一个简单的算法以保证生成随机数的不同

Random rand =new Random();

for ( int i = 1 ; i < VcodeNum+1 ; i++ ) {

if ( temp != -1) {

rand =new Random(i*temp*unchecked((int)DateTime.Now.Ticks));

}

int t = rand.Next(35) ;

if (temp != -1 && temp == t) {

return RndNum( VcodeNum );

}

temp = t ;

VNum += VcArray[t];

}

return VNum ;

}

</script>