ASP.Net MVC 生成安全验证码(例：用于登陆验证)

---------html　　　　　　

< td >验证码： td >
           < td >
               < img  src="/Login/CheckCode?ID=1" id="imgCode" alt="单击可刷新" onclick="ClickRemoveChangeCode()"  />
               < div  style="float:right; margin-top: 5px;">
                   < a  href="javascript:void(0)" onclick="ClickRemoveChangeCode();return false;">看不清，换一张 a >
               div >
           td >

 

-----------jquery

//单击重新改变验证码
function  ClickRemoveChangeCode() {
    var  code = $( "#imgCode" ).attr( "src" );
    $( "#imgCode" ).attr( "src" , code +  "1" );
}

 

 

------------asp.net mvc 返回文件地址　　　　

///
/// 验证码的校验
///
///
///
public  ActionResult CheckCode()
{
    //生成验证码
    ValidateCode validateCode =  new  ValidateCode();
    string  code = validateCode.CreateValidateCode(4);
    Session[ "ValidateCode" ] = code;
    byte [] bytes = validateCode.CreateValidateGraphic(code);
    return  File(bytes,  @"image/jpeg" );
}

 

----生成验证码和绘制背景的类

public  class  ValidateCode
    {
        public  ValidateCode()
        {
        }
        ///
        /// 验证码的最大长度
        ///
        public  int  MaxLength
        {
            get  {  return  10; }
        }
        ///
        /// 验证码的最小长度
        ///
        public  int  MinLength
        {
            get  {  return  1; }
        }
        ///
        /// 生成验证码
        ///
        /// 指定验证码的长度
        ///
        public  string  CreateValidateCode( int  length)
        {
            int [] randMembers =  new  int [length];
            int [] validateNums =  new  int [length];
            string  validateNumberStr =  "" ;
            //生成起始序列值
            int  seekSeek =  unchecked (( int )DateTime.Now.Ticks);
            Random seekRand =  new  Random(seekSeek);
            int  beginSeek = ( int )seekRand.Next(0, Int32.MaxValue - length * 10000);
            int [] seeks =  new  int [length];
            for  ( int  i = 0; i < length; i++)
            {
                beginSeek += 10000;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for  ( int  i = 0; i < length; i++)
            {
                Random rand =  new  Random(seeks[i]);
                int  pownum = 1 * ( int )Math.Pow(10, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for  ( int  i = 0; i < length; i++)
            {
                string  numStr = randMembers[i].ToString();
                int  numLength = numStr.Length;
                Random rand =  new  Random();
                int  numPosition = rand.Next(0, numLength - 1);
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
            }
            //生成验证码
            for  ( int  i = 0; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return  validateNumberStr;
        }

        //C# MVC 升级版
        ///
        /// 创建验证码的图片
        ///
        /// 要输出到的page对象
        /// 验证码
        public  byte [] CreateValidateGraphic( string  validateCode)
        {
            Bitmap image =  new  Bitmap(( int )Math.Ceiling(validateCode.Length * 12.0), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成随机生成器
                Random random =  new  Random();
                //清空图片背景色
                g.Clear(Color.White);
                //画图片的干扰线
                for  ( int  i = 0; i < 25; i++)
                {
                    int  x1 = random.Next(image.Width);
                    int  x2 = random.Next(image.Width);
                    int  y1 = random.Next(image.Height);
                    int  y2 = random.Next(image.Height);
                    g.DrawLine( new  Pen(Color.Silver), x1, y1, x2, y2);
                }
                Font font =  new  Font( "Arial" , 12, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush =  new  LinearGradientBrush( new  Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f,  true );
                g.DrawString(validateCode, font, brush, 3, 2);
                //画图片的前景干扰点
                for  ( int  i = 0; i < 100; i++)
                {
                    int  x = random.Next(image.Width);
                    int  y = random.Next(image.Height);
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
                }
                //画图片的边框线
                g.DrawRectangle( new  Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                //保存图片数据
                MemoryStream stream =  new  MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //输出图片流
                return  stream.ToArray();
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }

        ///
        /// 得到验证码图片的长度
        ///
        /// 验证码的长度
        ///
        public  static  int  GetImageWidth( int  validateNumLength)
        {
            return  ( int )(validateNumLength * 12.0);
        }
        ///
        /// 得到验证码的高度
        ///
        ///
        public  static  double  GetImageHeight()
        {
            return  22.5;
        }

    }