C#实现数字字母混合随机产生验证码

【实例截图】

【核心代码】

using System;

using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApp7
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if(textBox1 .Text .Trim ()==null||textBox1 .Text .Trim ()=="")
            {
                MessageBox.Show("请输入验证码！！", "警告", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
            }
            else
            {
                if(textBox1 .Text .Trim ()==strValidateCode )
                {
                    MessageBox.Show("验证通过!", "通过", MessageBoxButtons.OK, MessageBoxIcon.Information);
                }
                else
                {
                    MessageBox.Show("验证码错误！！", "错误", MessageBoxButtons.OK, MessageBoxIcon.Error);
                }
            }
        }
        private string checkCode = String.Empty;
        private string strValidateCode;
        public string GetRandomNumberString(int Number)
        {
            string strNumber = string.Empty;
            Random theRandomNumber = new Random();
            for (int i = 0; i < Number; i  )
            {
                strNumber  = theRandomNumber.Next(10).ToString();
            }
            return strNumber;
        }
        public string GetRandomAlpahabetString(int Number)
        {
            string strAlphabet = string.Empty;
            Random theRandomAlphabet = new Random();
            for (int i = 0; i < Number; i  )
            {
                char ch = (char)theRandomAlphabet.Next(97, 122);
                strAlphabet  = ch;
            }
            return strAlphabet;
        }
        public string GetRandomAlphbetOrNumberString(int Number)
        {
            string strAlphabetOrNumber = string.Empty;
            Random theRandomAlphabetOrNumber = new Random();
            int ran = theRandomAlphabetOrNumber.Next(2);
            int numAlphabet = theRandomAlphabetOrNumber.Next(Number);
            int numNumber = Number - numAlphabet;

            if (ran == 1)
            {
                for (int i = 0; i < numAlphabet; i  )
                {
                    char ch = (char)theRandomAlphabetOrNumber.Next(97, 122);
                    strAlphabetOrNumber  = ch;
                }
                for (int i = 0; i < numNumber; i  )
                {
                    strAlphabetOrNumber  = theRandomAlphabetOrNumber.Next(10);
                }
            }
            else
            {
                for (int i = 0; i < numNumber; i  )
                {
                    strAlphabetOrNumber  = theRandomAlphabetOrNumber.Next(10);
                }
                for (int i = 0; i < numAlphabet; i  )
                {
                    char ch = (char)theRandomAlphabetOrNumber.Next(97, 122);
                    strAlphabetOrNumber  = ch;
                }
            }
            return strAlphabetOrNumber;
        }
        private void CreateCheckCodeImage(string checkCode)
        {
            if (checkCode == null || checkCode.Trim() == String.Empty)
            {
                return;
            }
            int int_ImageWidth = strValidateCode.Length * 13;
            Bitmap image = new Bitmap(int_ImageWidth, 20);
            Graphics g = Graphics.FromImage(image);
            try
            {
                Random random = new Random();
                g.Clear(Color.White);
                for (int i = 0; i < 25; i  )
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int x3 = random.Next(image.Width);
                    int x4 = random.Next(image.Width);
                    g.DrawLine(new Pen(Color.Silver), x1, x2, x3, x4);
                }
                Font font = new Font("Arial", 12, (System.Drawing.FontStyle.Bold | FontStyle.Italic));
                System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(checkCode, font, brush, 2, 2);
                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()));
                }
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                this.pictureBox1.Width = image.Width;
                this.pictureBox1.Height = image.Height;
                this.pictureBox1.Image = image;

            }
            catch (Exception error)
            {
                MessageBox.Show(error.Message);
                g.Dispose();
            }
        }
        private void RadomString()
        {
            strValidateCode = GetRandomAlphbetOrNumberString(4);
            CreateCheckCodeImage(strValidateCode);
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            RadomString();
        }

        private void pictureBox1_Click(object sender, EventArgs e)
        {
            RadomString();
        }
    }
}