C# 生成简单验证码

网站登录总是会用到验证码，生成验证码对于C#来说很简单。因为有专门封装好的GDI+类可以直接调用使用具体代码如下

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Web;
 using System.Web.UI;
 using System.Web.UI.WebControls;
 using System.Drawing;

 namespace Ajax.验证码
 {
     public partial class Yanma : System.Web.UI.Page
     {
         private int CodeNum = ;
         private string codeNum = "";
         protected void Page_Load(object sender, EventArgs e)
         {
             VeriflcationCode();
             HuaCode(codeNum);
         }

         private void VeriflcationCode()
         {
             //生成验证码
             string AllChar = "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,W,X,Y,Z";
             string[] StrChar = AllChar.Split(',');
             Random rd = new Random();
             string Codes = "";
             for (int i = ; i < CodeNum; i++)
             {
                 Codes += StrChar[rd.Next(, )];
             }
             codeNum = Codes;
             Session["VerCode"] = Codes;
         }

         private void HuaCode(string Codes)
         {
             int iwidth = (int)(Codes.Length * );//定义画布的宽
             System.Drawing.Bitmap images = new System.Drawing.Bitmap(iwidth, );//声明一个画布类，初始化图片的宽和高

             Graphics g = Graphics.FromImage(images);
             Font f = new Font("Arial", );//定义文字类型
             Brush b = new System.Drawing.SolidBrush(Color.Black);//文字颜色 黑色
             Brush r = new System.Drawing.SolidBrush(Color.FromArgb(, , ));//文字颜色
             g.Clear(System.Drawing.ColorTranslator.FromHtml("#99C1CB"));//背景色

             char[] ch = Codes.ToCharArray();
             for (int i = ; i < ch.Length; i++)
             {
                 if (ch[i] >= '' && ch[i] <= '')
                 {
                     //数字用红色显示
                     g.DrawString(ch[i].ToString(), f, r,  + (i * ), );//将文字画出 文字、字体类型、字体颜色、字体间距、字体于顶部间距
                 }
                 else
                 {   //字母用黑色显示
                     g.DrawString(ch[i].ToString(), f, b,  + (i * ), );
                 }
             }

             //for循环用来生成一些随机的水平线
             Pen blackPen = new Pen(Color.Black, );
             Random rand = new Random();
             for (int i = ; i < ; i++)
             {
                 int y = rand.Next(images.Height);
                 g.DrawLine(blackPen, , y, images.Width, y);
             }

             System.IO.MemoryStream ms = new System.IO.MemoryStream();
             images.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
             //history back 不重复
             Response.Cache.SetNoStore();//这一句
             Response.ClearContent();
             Response.ContentType = "image/Jpeg";
             Response.BinaryWrite(ms.ToArray());
             g.Dispose();
             images.Dispose();
         }

效果为：