随机生成图片验证码(C#)

代码

 

 

---ValidationCodeImg.aspx
<%@ import namespace="System"%>
<%@ import namespace="System.IO"%>
<%@ import namespace="System.Drawing"%>
<%@ import namespace="System.Drawing.Imaging"%>
<%@ import namespace="System.Drawing.Drawing2D"%>
<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["VNum"]=VNum;
       ValidateCode(VNum);
   }
}
public void  ValidateCode(string VNum)
{
    validateimage = new Bitmap(70, 20, PixelFormat.Format24bppRgb);
    g = Graphics.FromImage(validateimage);
    g.DrawString(VNum, new Font("Verdana",15),new SolidBrush(Color.White),new PointF(8,0));
    g.FillRectangle(new LinearGradientBrush(new Point(0,0), new Point(110,20), Color.FromArgb(0,0,0,0),Color.FromArgb(255,255,60,40)),0,0,120,30);
    g.Save();
    MemoryStream ms=new MemoryStream();
    validateimage.Save(ms,System.Drawing.Imaging.ImageFormat.Gif);
    Response.ClearContent();
    Response.ContentType="image/gif";
    Response.BinaryWrite(ms.ToArray());
    Response.End();
}
string MakeValidateCode()
{
   char[] s = new char[]{'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','v','w','x','y','z','A','B','C','D','E','F','G' ,'H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W' ,'X','Y','Z'};
   string num = "";
   Random r = new Random();
   for(int i = 0; i < 5; i++)
   {
      num += s[r.Next(0, s.Length)].ToString();
   }
   return num;
}
</script>
---ShowValidationCodeImg.aspx
<asp:Image id="Image1" runat="server" ImageUrl="ValidationCodeImg.aspx"></asp:Image>
使用方法
现在，已经生成了图片验证码，在需要进行验证时，将MakeValidateCode()生成的字符串传递给相应的验证函数即可。