字母／数字／汉字验证码的生成

 
效果如下：
－－－＞

代码如下：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace 验证码
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        //生成随机汉字验证码
        private void button1_Click(object sender, EventArgs e)
        {
            this.button1.BackColor = AttionColor ();
            this.button1.ForeColor = Color.Red;
            Random r=new Random();
            //获取GB2312编码页（表）
            Encoding gb = Encoding.GetEncoding("gb2312");
            //调用函数产生4个随机中文汉字编码
            object[] bytes = CreateRegionCode(4);
            //根据汉字编码的字节数组解码出中文汉字
            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[])));
            this.button1.Text = str1 + str2 + str3 + str4;
            
        }
        /**/
        /*
     此函数在汉字编码范围内随机创建含两个元素的十六进制字节数组，每个字节数组代表一个汉字，并将
     四个字节数组存储在object数组中。
     参数：strlength，代表需要产生的汉字个数
    */
      
        //生成随机汉字验证码方法
        public static object[] CreateRegionCode(int strlength)
        {
            //定义一个字符串数组储存汉字编码的组成元素
            string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
            Random rnd = new Random();
            //定义一个object数组用来
            object[] bytes = new object[strlength];
            /**/
            /*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中
          每个汉字有四个区位码组成
          区位码第1位和区位码第2位作为字节数组第一个元素
          区位码第3位和区位码第4位作为字节数组第二个元素
        */
            for (int i = 0; i < strlength; i++)
            {
                //区位码第1位
                int r1 = rnd.Next(11, 14);
                string str_r1 = rBase[r1].Trim();
                //区位码第2位
                rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);//更换随机数发生器的
                //种子避免产生重复值
                int r2;
                if (r1 == 13)
                {
                    r2 = rnd.Next(0, 7);
                }
                else
                {
                    r2 = rnd.Next(0, 16);
                }
                string str_r2 = rBase[r2].Trim();
                //区位码第3位
                rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);
                int r3 = rnd.Next(10, 16);
                string str_r3 = rBase[r3].Trim();
                //区位码第4位
                rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);
                int r4;
                if (r3 == 10)
                {
                    r4 = rnd.Next(1, 16);
                }
                else if (r3 == 15)
                {
                    r4 = rnd.Next(0, 15);
                }
                else
                {
                    r4 = rnd.Next(0, 16);
                }
                string str_r4 = rBase[r4].Trim();
                //定义两个字节变量存储产生的随机汉字区位码
                byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);
                byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);
                //将两个字节变量存储在字节数组中
                byte[] str_r = new byte[] { byte1, byte2 };
                //将产生的一个汉字的字节数组放入object数组中
                bytes.SetValue(str_r, i);
            }
            return bytes;
        }

        //验证码输入正确！
        private void button2_Click(object sender, EventArgs e)
        {
            if (this.textBox1.Text == this.button1.Text　|| this .textBox1 .Text ==this.button3.Text )
                MessageBox.Show("验证码输入正确！");
        }

        //随机生成颜色
        public Color AttionColor()
        {
            Color color = new Color();
            Random random = new Random();
            color = Color.FromArgb(255, random.Next(255), random.Next(255), random.Next(255));
          //  MessageBox.Show(color .ToArgb ().ToString ());
            return color;
        }
      
        //点击随机生成数字或字母
        private void button3_Click(object sender, EventArgs e)
        {
            this.button3.Text = CreateValidate(5);//生成几个随机数　
            this.button3.ForeColor = AttionColor();
        }

       //生成0－9　Ａ－Ｚ　的随机数
        private string CreateValidate(int count)
        {
            string allChar = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
            string[] allCharArray = allChar.Split(',');
            string randomCode = "";
            int temp = -1;
            Random rand = new Random();
            for (int i = 0; i < count; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
                }
                int t = rand.Next(35);
                if (temp == t)
                {
                    return CreateValidate(count);
                }
                temp = t;
                randomCode += allCharArray[t];
            }
            
            return randomCode;
        }

        //大小写字母转换
        private void button4_Click(object sender, EventArgs e)
        {
            string inputStr = this.textBox1 .Text  ;
            char[] outputStr = new char[inputStr.Length];
            string s = string.Empty;
            for (int i = 0; i < textBox1.Text.Length; i++)
            {
                if (inputStr >= 'a' && inputStr <= 'z')
                    outputStr = (char)(inputStr - ('a' - 'A'));
                if (inputStr >= 'A' && inputStr <= 'Z')
                    outputStr = (char)(inputStr + ('a' - 'A'));
            }
            for (int i = 0; i < outputStr.Length; i++)
            {
                s = s + outputStr.ToString();
            }
            this.button4.Text = s;
        }    
    }
}