C#生成汉字验证码的方法

首先，我们需要用到Graphics对象与Encoding对象，所以，应该在添加下列引用：

using System.Text;
using System.Drawing;

先写一个方法CreateStringCode，用于获得汉字的4位区位码:

 private object[] CreateStringCode(int strLength)
    {
        //定义一个数组存储汉字编码的组成元素
         string[] str = new string[16] {"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f" };
        Random rand = new Random();
        object[] objects = new object[strLength];
        for (int i = 0; i < strLength; i++)
        {
            //获取区位码第一位，汉字在第16区B0开始，所以随机生成的汉字的区位码第一位在B、C、D之间
           int code1 = rand.Next(11, 14);
            string str1 = str[code1].Trim();

            rand = new Random();
            int code2;
            //如果取到的第一位验证码为d，那么第二位验证码只能在0-6中取，因为D7之后都是些繁杂汉字
             if(code1 == 13)
                code2 = rand.Next(0,7);
            else
                code2 = rand.Next(0,16);
            string str2 = str[code2].Trim();
            
            //获取区位码第三位
             rand= new Random(code2 * unchecked((int)DateTime.Now.Ticks) + i);
            int code3= rand.Next(10,16);
            string str3 = str[code3].Trim();

            //获取区位码第四位
         //区位码表每区的第一个位置和最后一个位置都是空的，没有汉字，
        //因此随机生成的区位码第3位如果是A的话，第4位就不能是0；第3位如果是F的话，第4位就不能是F。
             rand = new Random(code3  * unchecked((int)DateTime.Now.Ticks)+ i);
            int code4;
            if(code3 == 10)
                code4 = rand.Next(1,16);
            else if(code3 == 13)
                code4=  rand.Next(0,15);
            else
                code4 = rand.Next(0,16);
            string str4 = str[code4].Trim();

            byte byte1 = Convert.ToByte(str1 + str2,16);
            byte byte2 = Convert.ToByte(str3 + str4, 16);
            byte[] strAdd = new byte[] {byte1,byte2 };

            objects.SetValue(strAdd, i);
        }
        return objects;
    }

 

 

然后编写方法getString，将得到的汉字编码转换为汉字:

 

 private string getString(int length)
    {
        Encoding gb = Encoding.GetEncoding("gb2312");
        object[] bytes = CreateStringCode(length);

        string str1 = gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[])));
        string str2 = gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])));
        string str3 = gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])));
        string str4 = gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[])));

        string str = str1 +  " " + str2 + str3 + str4;

        return str;
    }

 

编写方法GraphicsImage，在页面中画出所生成的汉字：

 

 private void GraphicsImage(int Length)
    {
        //生成Bitmap对象
        System.Drawing.Bitmap image = 
            new System.Drawing.Bitmap((int)Math.Ceiling((getString(Length).Length * 32.5)),42);

        Graphics g = Graphics.FromImage(image);

        try
        {
            Random rand = new Random();
            //设置背景色
            g.Clear(Color.White);
            //画两条噪音线
            for (int i = 0; i < 2; i++)
            {
                int x1 = rand.Next(image.Width);
                int x2 = rand.Next(image.Width);
                int y1 = rand.Next(image.Height);
                int y2 = rand.Next(image.Height);
                g.DrawLine(new Pen(Color.FromArgb(rand.Next())), x1, y1, x2, y2);
            }
            //生成字体对象，设置字体
            Font font = new System.Drawing.Font("黑体", 24, System.Drawing.FontStyle.Bold);
            //设置字体的颜色，纹路，渐变等
            System.Drawing.Drawing2D.LinearGradientBrush brush =
                new System.Drawing.Drawing2D.LinearGradientBrush(
                    new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.Red, 1.2f, true);
            g.DrawString(getString(Length), font, brush, 2, 2);
            //在图片上生成1000个噪音点
            for (int i = 0; i < 1000; i++)
            {
                int x = rand.Next(image.Width);
                int y = rand.Next(image.Height);
                image.SetPixel(x, y, Color.FromArgb(rand.Next()));
            }
            //画出边框
            g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
            //保存，格式为Gif
            System.IO.MemoryStream ms = new System.IO.MemoryStream();
            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
            //输出
            Response.ClearContent();
            Response.ContentType = "image/Gif";
            Response.BinaryWrite(ms.ToArray());
        }
        catch (Exception ms)
        {
            Response.Write(ms.Message);
        }
    }

 

最后在页面的Page_Load事件中调用一下：

 

 protected void Page_Load(object sender, EventArgs e)
    {
        GraphicsImage(4);
    }

 

 

效果如下图所示：