差不多生成图片就如下面.
<script language="C#" runat="server">
private Bitmap validateimage;
private Graphics g;
public void Page_Load(object Sender ,EventArgs e ){
if (!IsPostBack){
string vNum =MakeValidateCode( );
Session["code"]=vNum;
ValidateCode(vNum);}
}
public void ValidateCode(string vNum)
{
validateimage = new Bitmap(40, 15,PixelFormat.Format24bppRgb);
g = Graphics.FromImage(validateimage);
g.FillRectangle(new LinearGradientBrush(new Point(0,0), new Point(90,20), Color.FromArgb(240,255,255,255),Color.FromArgb(240,255,255,255)),0,0,40,15);
g.DrawString(vNum, new Font("tahoma", 10), new SolidBrush(Color.Blue), new PointF(4, 0));
g.Save();
MemoryStream ms=new MemoryStream();
validateimage.Save(ms,System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType="image/bmp";
Response.BinaryWrite(ms.ToArray());
Response.End();
}
string MakeValidateCode()
{
char[] s = new char[]{'0','1', '2','3','4','5','6','7','8','9'};
string num = "";
Random r = new Random();
for(int i = 0; i < 4; i++)
{
num =num+ s[r.Next(0, s.Length)].ToString();
}
return num;
}
</script>