validatecode.cs

征服ASP.NET 2.0 Ajax 典型应用源码

using System.Text;
using System;
using System.Web;
using System.IO;
using System.Drawing;
using System.Drawing.Imaging;
	/// <summary>
	/// Cls_PicVcode生成图片
	/// </summary>
	public class ValidateCode
	{
        /// <summary>
        /// 该方法用于生成指定位数的随机数
        /// </summary>
        /// <param name="VcodeNum">参数是随机数的位数</param>
        /// <returns>返回一个随机数字符串</returns>
        private string RndNum(int VcodeNum)
        {
            //验证码可以显示的字符集合
            string Vchar = "1,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,p,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,P,P,Q" +
                ",R,S,T,U,V,W,X,Y,Z";
            string[] VcArray = Vchar.Split(new Char[] { ',' });//拆分成数组
            string VNum = "";//产生的随机数
            int temp = -1;//记录上次随机数值，尽量避避免生产几个一样的随机数

            Random rand = new Random();
            //采用一个简单的算法以保证生成随机数的不同
            for (int i = 1; i < VcodeNum + 1; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));//初始化随机类
                }
                int t = rand.Next(61);//获取随机数
                if (temp != -1 && temp == t)
                {
                    return RndNum(VcodeNum);//如果获取的随机数重复，则递归调用
                }
                temp = t;//把本次产生的随机数记录起来
                VNum += VcArray[t];//随机数的位数加一
            }
            return VNum;
        }
        
        /// <summary>
		/// 该方法是将生成的随机数写入图像文件
		/// </summary>
		/// <param name="VNum">VNum是一个随机数</param>
        public MemoryStream Create(out string VNum)
        {
         VNum = RndNum(4) ;
            Bitmap Img = null;
            Graphics g = null;
            MemoryStream ms = null;
            System.Random random = new Random();
            //验证码颜色集合
            Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
          //验证码字体集合
            string[] fonts ={ "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
           

            //定义图像的大小，生成图像的实例
            Img = new Bitmap((int)VNum.Length*18, 32);
            
            g = Graphics.FromImage(Img);//从Img对象生成新的Graphics对象  
          
            g.Clear(Color.White);//背景设为白色
            
            //在随机位置画背景点
            for (int i = 0; i < 100; i++)
            {
                int x = random.Next(Img.Width);
                int y = random.Next(Img.Height);
                g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
            }
            //验证码绘制在g中
            for (int i = 0; i < VNum.Length; i++)
            {
                int cindex = random.Next(7);//随机颜色索引值
                int findex = random.Next(5);//随机字体索引值
                Font f = new System.Drawing.Font(fonts[findex], 13, System.Drawing.FontStyle.Bold);//字体
                Brush b = new System.Drawing.SolidBrush(c[cindex]);//颜色
                int ii = 4;
                if ((i + 1) % 2 == 0)//控制验证码不在同一高度
                {
                    ii = 2;
                }
                g.DrawString(VNum.Substring(i, 1), f, b, 3 + (i * 12), ii);//绘制一个验证字符
            }
            ms = new MemoryStream();//生成内存流对象
            Img.Save(ms, ImageFormat.Jpeg);//将此图像以Png图像文件的格式保存到流中
           
            //回收资源
            g.Dispose();
            Img.Dispose();
            return ms;

        }

      
	}