c# winform 生成验证码

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace abcValidator
{
    public partial class Form1 : Form
    {
        PictureBox picCode = null;
        Button btnCode = null;
        TextBox txtUserCode = null;
        Button btnUserCode = null;
        private string code = string.Empty;
        public Form1()
        {
            InitializeComponent();
            this.Load+=new EventHandler(Form1_Load);
        }
        private void Form1_Load(object sender, EventArgs e)
        {
            picCode = new PictureBox();
            picCode.Location = new Point(10, 10);
            this.Controls.Add(picCode);
            btnCode = new Button();
            btnCode.Location = new Point(picCode.Location.X + picCode.Width + 10, 10);
            btnCode.Text = "生成验证码";
            btnCode.Click += new EventHandler(btnCode_Click);
            this.Controls.Add(btnCode);
            txtUserCode = new TextBox();
            txtUserCode.Location = new Point(10, picCode.Location.Y + picCode.Height + 5);
            this.Controls.Add(txtUserCode);
            btnUserCode = new Button();
            btnUserCode.Location = new Point(picCode.Location.X + picCode.Width + 10, picCode.Location.Y + picCode.Height + 5);
            btnUserCode.Text = "验证验证码";
            btnUserCode.Click += new EventHandler(btnUserCode_Click);
            this.Controls.Add(btnUserCode);
            code = CheckCode();
            CodeImage(code, picCode);
        }
        /// <summary>
        /// 验证验证码
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void btnUserCode_Click(object sender, EventArgs e)
        {
            string realCode = code.Replace(" ", "");
            if (txtUserCode.Text.Trim().ToLower().Equals(realCode.ToLower()))
            {
                MessageBox.Show("ok");
            }
            else
            {
                MessageBox.Show("failure");
            }
        }
        /// <summary>
        /// 生成验证码
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        void btnCode_Click(object sender, EventArgs e)
        {
            code = CheckCode();
            CodeImage(code, picCode);
        }
        private string CheckCode()        //此方法生成
        {
            int number;
            char code;
            string checkCode = String.Empty;     //声明变量存储随机生成的4位英文或数字
            Random random = new Random();      //生成随机数
            for (int i = 0; i < 4; i++)
            {
                number = random.Next();       //返回非负随机数
                if (number % 2 == 0)       //判断数字是否为偶数
                    code = (char)('0' + (char)(number % 10));
                else           //如果不是偶数
                    code = (char)('A' + (char)(number % 26));
                checkCode += " " + code.ToString();    //累加字符串
            }
            return checkCode;         //返回生成的字符串
        }
        private void CodeImage(string checkCode, PictureBox picCode)
        {
            if (checkCode == null || checkCode.Trim() == String.Empty)
                return;
            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 9.5)), 22);
            Graphics g = Graphics.FromImage(image);     //创建Graphics对象
            try
            {
                Random random = new Random();      //生成随机生成器
                g.Clear(Color.White);         //清空图片背景色
                for (int i = 0; i < 3; i++)       //画图片的背景噪音线
                {
                    int x1 = random.Next(image.Width);
                    int x2 = random.Next(image.Width);
                    int y1 = random.Next(image.Height);
                    int y2 = random.Next(image.Height);
                    g.DrawLine(new Pen(Color.Black), x1, y1, x2, y2);
                }
                Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold));
                g.DrawString(checkCode, font, new SolidBrush(Color.Red), 2, 2);
                for (int i = 0; i < 150; i++)      //画图片的前景噪音点
                {
                    int x = random.Next(image.Width);
                    int y = random.Next(image.Height);
                    image.SetPixel(x, 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);
                picCode.Width = image.Width;    //设置PictureBox的宽度
                picCode.Height = image.Height;    //设置PictureBox的高度
                picCode.BackgroundImage = image;   //设置PictureBox的背景图像
            }
            catch
            { }
        }
    }
}