C#验证码

界面展示
<img id="zsCode" />
<a id="id" style="cursor:pointer">换一张</a>

//验证码的生成
int verifyLength=6;
int width=100, height=20;
SizeF verifyTextSize;
Bitmap bitmap=new Bitmap(Server.MapPath("~/pic/img.jpg"),true);//干扰图片

TextureBrush brush=new TextureBrush (bitmap);

string verifyText=VerifyText(verifyLength)//获取验证码
Session["VerifyCode"]=verifyText.ToUpper();//存储验证码
Font font=new Font("Arial",14,FontStyle.Bold);
Bitmap image=new Bitmap(width,height);
Graphics gs=Graphics.FromImage(image);
gs.Clear(Color.White);//清空背景色

//绘制验证码

verifyTextSize=gs.MeasureString(verifyText,font,brush,(width-verifyTextSize.Width)/2,(height-verifyTextSize.Height)/2);

image.Save(Response.OutputStream,system.Drawing.Imaging.ImageFormat.Jpeg);

gs.DrawString(verifyText,font,);


public static string VerifyText(int length)
{
    char[] verify=new Char[length];
    Random rnd=new Random();
    char[] dic={'A','B','C','a','b','c','1','9'}; //想要出现在验证码中的字母数字 (区分大小写)    不一一全写了
    for(int i=0;i<length;i++)
  {
      verify[i]=dic[rnd.Next(dic.Length-1)];
  }
     return new string (verify);  
}


//换一张  

 $("#id").click(function(){
   $("#zsCode").attr("src","/user/verycode?"+ new Date());
})

//登录时验证

   if(Session["VerifyCode"]==null ||Session["VerifyCode"].ToString()=="")
return "验证码失效";
 else if(string.IsNUllOrEmpty(login.yzCode)||Session["VerifyCode"].ToString()!=login.yzCode.ToUpper());
 return "验证码错误";