一个图片验证码的实现

来源：互联网发布：乐视网络电视怎么下载编辑：程序博客网时间：2024/05/19 19:43

转 http://blog.henryfan.net/post/2012/10/24/一个基于数字的图片验证码的实现.aspx

其实实现一个图片验证码并不是什么难的问题,主要讲究的时验证的实现上如何提高程序的识别难度.所以在实现过程参考了一下google的做法,由于数字或字母适当重叠对人自身识别并不成什么问题,但对于计算增加的难度相对来说就比较高些了.如果感觉难度不大可以调整一下程序让让字母之间紧靠的近一点,也可适当地加下曲线来让分析上更难.不过做得太过的话,估计人自己都搞不清楚了:)

验证码效果

具体实现代码

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using System; 
using System.Collections.Generic; 
using System.Drawing; 
using System.Drawing.Drawing2D; 
using System.Text; 
  
namespaceSmark.ImageNumber 
{ 
    /// 
    /// Copyright © henryfan 2012        
    /// Email:  henryfan@msn.com    
    /// HomePage:  http://www.ikende.com       
    /// CreateTime: 2012/10/23 21:18:29
    /// 
    publicclass Generator 
    {
        conststring VALUE = "123456789"; 
  
        privatestatic Dictionary mCharImages =new Dictionary(26);
  
        privatestatic Image mLine;
  
        privatestatic Random mRam =new Random();
  
        publicstatic stringGeneratorCode() 
        {
            stringcode = "";
            for(int i = 0; i < 4; i++) 
            {
                code += VALUE.Substring(GetRamValue() % VALUE.Length, 1);
            }
            returncode; 
  
        }
  
        staticint GetRamValue()
        {
  
            returnmRam.Next(); 
        }
  
        publicstatic Image GetImage(stringcode) 
        {
            Bitmap tmpImg =new Bitmap(100, 40);
            using(Graphics e = Graphics.FromImage(tmpImg)) 
            {
  
                intoffset = 2; 
  
                e.FillRectangle(newSolidBrush(Color.White), 0, 0, 200, 60); 
  
                List items =new List();
                foreach(char key in code)
                {
                    items.Add(GetGeneratorItem(key));
                }
                for(int i = 0; i < items.Count; i++) 
                {
                    if(i > 0) 
                    {
                        if((items[i].Value < 0 && items[i - 1].Value > 0) || (items[i].Value > 0 && items[i - 1].Value > 0)
                            || (items[i].Value < 0 && items[i - 1].Value < 0))
                            offset += 12;
  
                        else
                            offset += 18;
                    }
                    using(Image img = items[i].DrawImage()) 
                    {
                        if(Math.Abs(items[i].Value) > 20) 
                            e.DrawImage(img, offset, 6);
                        elseif (Math.Abs(items[i].Value) > 20)
                            e.DrawImage(img, offset, 4);
                        else
                            e.DrawImage(img, offset, 2);
                    }
  
                }
  
  
            }
            returntmpImg; 
        }
  
        publicstatic System.Collections.IEnumerable GetKeys
        {
            get
            {
                returnmCharImages.Keys; 
            }
        }
  
        privatestatic GeneratorItem GetGeneratorItem(charkey) 
        {
            GeneratorItem item =new GeneratorItem();
            intvalue = GetRamValue() % 25; 
            if(value < 10) 
                value = 10;
            if(GetRamValue() % 2 == 0) 
                value = -value;
            item.Value = value;
            item.Key = key;
            returnitem; 
        }
  
        classGeneratorItem 
        {
            publicint Value { get; set; }
            publicchar Key { get; set; }
            publicImage DrawImage() 
            {
                Bitmap tmpImg =new Bitmap(50, 50);
                using(Graphics e = Graphics.FromImage(tmpImg)) 
                {
                    e.RotateTransform(Value, System.Drawing.Drawing2D.MatrixOrder.Append);
                    e.DrawImage(mCharImages[Key], 0, 0);
                    e.Flush();
                }
                returntmpImg; 
            }
        }
  
        staticGenerator() 
        {
  
            HatchBrush sb =new HatchBrush(HatchStyle.Percent40, Color.Black, Color.Black);
  
            foreach(char item in VALUE)
            {
  
                Bitmap bmp =new Bitmap(50, 50);
                using(Graphics g = Graphics.FromImage(bmp)) 
                {
                    g.DrawString(newstring(newchar[] { item }),new Font("宋体", 24, FontStyle.Italic), sb, 2, 2);
                }
                mCharImages[item]= bmp;
            }
  
            mLine =new Bitmap(60, 4);
            using(Graphics g = Graphics.FromImage(mLine)) 
            {
                g.FillRectangle(sb, 0, 0, 60, 3);
            }
  
        }
    }
}