C#验证码

环境是.net 5开发。

1.建立一个项目

2.代码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
 
namespace WinFormsApp1
{
    public partial class Form1 : Form
    {
        /// <summary>
        /// 验证码的值
        /// </summary>
        public string txt = string.Empty;
        public Form1()
        {
            InitializeComponent();
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
            GetLettersNumbers();
        }
 
        private void button2_Click(object sender, EventArgs e)
        {
            GetChinese();
        }
 
        private void button3_Click(object sender, EventArgs e)
        {
            if (textBox1.Text.Trim() != txt)
            {
                MessageBox.Show("提示：验证码输入错误，请重新输入！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
            else
            {
                MessageBox.Show("提示：验证码输入正确！", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
        }
 
        /// <summary>
        /// 字母和数字
        /// </summary>
        private void GetLettersNumbers()
        {
            //颜色列表，用于验证码、噪线、噪点 
            Color[] color = { Color.Black, Color.Red, Color.Blue, Color.Green, Color.Orange, Color.Brown, Color.Brown, Color.DarkBlue };
            //字体列表，用于验证码 
            string[] font = { "Times New Roman" };
            //验证码的字符集，去掉了一些容易混淆的字符 
            char[] character = { '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'd', 'e', 'f', 'h', 'k', 'm', 'n', 'r', 'x', 'y', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L', 'M', 'N', 'P', 'R', 'S', 'T', 'W', 'X', 'Y' };
            Random rnd = new Random();
            //生成验证码字符串 
            txt = "";
            for (int i = 0; i < 4; i++)
            {
                txt += character[rnd.Next(character.Length)];
            }
            //创建画布
            int codeW = txt.Length * 22;
            int codeH = 22;
            Bitmap bmp = new Bitmap(codeW, codeH);
            Graphics g = Graphics.FromImage(bmp);
            g.Clear(Color.White);
            //画噪线 
            for (int i = 0; i < 3; i++)
            {
                int x1 = rnd.Next(codeW);
                int y1 = rnd.Next(codeH);
                int x2 = rnd.Next(codeW);
                int y2 = rnd.Next(codeH);
                Color clr = color[rnd.Next(color.Length)];
                g.DrawLine(new Pen(clr), x1, y1, x2, y2);
            }
            //画验证码字符串 
            for (int i = 0; i < txt.Length; i++)
            {
                string fnt = font[rnd.Next(font.Length)];
                Font ft = new Font(fnt, 12);
                Color clr = color[rnd.Next(color.Length)];
                g.DrawString(txt[i].ToString(), ft, new SolidBrush(clr), (float)i * 18, (float)0);
            }
            pictureBox1.Image = bmp;
        }
 
 
        private void GetChinese()
        {
            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);//.net 5使用
            //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 = CreateCode(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[])));
            txt = str1 + str2 + str3 + str4;
            if (txt == null || txt == String.Empty)
            {
                return;
            }
            Bitmap image = new Bitmap((int)Math.Ceiling((txt.Length * 20.5)), 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);
                //画图片的背景噪音线
                for (int i = 0; i < 2; i++)
                {
                    Point tem_Point_1 = new Point(random.Next(image.Width), random.Next(image.Height));
                    Point tem_Point_2 = new Point(random.Next(image.Width), random.Next(image.Height));
                    g.DrawLine(new Pen(Color.Black), tem_Point_1, tem_Point_2);
                }
                Font font = new Font("宋体", 12, (FontStyle.Bold));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(txt, font, brush, 2, 2);
                //画图片的前景噪音点
                for (int i = 0; i < 100; i++)
                {
                    Point tem_point = new Point(random.Next(image.Width), random.Next(image.Height));
                    image.SetPixel(tem_point.X, tem_point.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);
                pictureBox1.Image = image;
            }
            catch
            {
                MessageBox.Show("生成失败");
            }
        }
        public object[] CreateCode(int strlength)
        {
            //定义一个字符串数组储存汉字编码的组成元素 
            string[] r = 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];
            for (int i = 0; i < strlength; i++)
            {
                //区位码第1位 
                int r1 = rnd.Next(11, 14);
                string str_r1 = r[r1].Trim();
                //区位码第2位 
                int r2;
                if (r1 == 13)
                    r2 = rnd.Next(0, 7);
                else
                    r2 = rnd.Next(0, 16);
                string str_r2 = r[r2].Trim();
                //区位码第3位 
                int r3 = rnd.Next(10, 16);
                string str_r3 = r[r3].Trim();
                //区位码第4位 
                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 = r[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;
        }
    }
}

3.效果

注意：

如果是.net 5的项目，nuget中增加，System.Text.Encoding.CodePages