C#生成圖形驗證碼

產生驗證碼圖片的源碼：

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing;
using System.IO;

public partial class CreatImage : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        string checkCode = CreateCode(4);
        Session["CheckCode"] = checkCode;
        CreateImage(checkCode);
    }

    /*產生驗證碼*/
    public string CreateCode(int codeLength)
    {
       
        string so = "1,2,3,4,5,6,7,8,9,0,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[] strArr=so.Split(',');
        string code = "";
        Random rand=new Random();
        for (int i = 0; i < codeLength; i++)
        {
            code+=strArr[rand.Next(0, strArr.Length)];
        }
        return code;
    }

    /*產生驗證圖片*/
    public void CreateImage(string code)
    {
       
        Bitmap image = new Bitmap(60, 20);
        Graphics g = Graphics.FromImage(image);
        WebColorConverter ww=new WebColorConverter();
        g.Clear((Color)ww.ConvertFromString("#FAE264"));