c#窗体实现验证码

在form窗体登录时，使用一些验证码，感觉挺有意思的。

    首先在窗体上放置上一个lable：请输入验证码。再放上一个text文本框，name=“txtValidCode”；然后在放入一个pictureBox。name="picValidCode";在放入一个按钮，text=“提交”。

在同层中加入一个类。ValidCode ，代码如下。

using System;
 
using System.Collections.Generic;
 
using System.Text;
 
using System.IO;
 
using System.Drawing;
 
using System.Drawing.Drawing2D;
 
 
 
namespace 实验1
{
 
    public class ValidCode
    {
 
        #region Private Fields
 
        private const double PI = 3.1415926535897932384626433832795;
 
        private const double PI2 = 6.283185307179586476925286766559;
 
        //private readonly int _wordsLen = 4; 
 
        private int _len;
 
        private CodeType _codetype;
 
        private readonly Single _jianju = (float)18.0;
 
        private readonly Single _height = (float)24.0;
 
        private string _checkCode;
 
        #endregion
 
        #region Public Property
 
        public string CheckCode
        {
 
            get
            {
 
                return _checkCode;
 
            }
 
        }
 
        #endregion
 
        #region Constructors
 
        /// <summary> 
 
        /// public constructors 
 
        /// </summary> 
 
        /// <param name="len"> 验证码长度 </param> 
 
        /// <param name="ctype"> 验证码类型：字母、数字、字母+ 数字 </param> 
 
        public ValidCode(int len, CodeType ctype)
        {
 
            this._len = len;
 
            this._codetype = ctype;
 
        }
 
        #endregion
 
        #region Public Field
 
        public enum CodeType { Words, Numbers, Characters, Alphas }
 
        #endregion
 
        #region Private Methods
 
 
 
        private string GenerateNumbers()
        {
 
            string strOut = "";
 
            System.Random random = new Random();
 
            for (int i = 0; i < _len; i++)
            {
 
                string num = Convert.ToString(random.Next(10000) % 10);
 
                strOut += num;
 
            }
 
            return strOut.Trim();
 
        }
 
 
 
        private string GenerateCharacters()
        {
 
            string strOut = "";
 
            System.Random random = new Random();
 
            for (int i = 0; i < _len; i++)
            {
 
                string num = Convert.ToString((char)(65 + random.Next(10000) % 26));
 
                strOut += num;
 
            }
 
            return strOut.Trim();
 
        }
 
        // 
 
        private string GenerateAlphas()
        {
 
            string strOut = "";
 
            string num = "";
 
            System.Random random = new Random();
 
            for (int i = 0; i < _len; i++)
            {
 
                if (random.Next(500) % 2 == 0)
                {
 
                    num = Convert.ToString(random.Next(10000) % 10);
 
                }
 
                else
                {
 
                    num = Convert.ToString((char)(65 + random.Next(10000) % 26));
 
                }
 
                strOut += num;
 
            }
 
            return strOut.Trim();
 
        }
 
 
 
        private System.Drawing.Bitmap TwistImage(Bitmap srcBmp, bool bXDir, double dMultValue, double dPhase)
        {
 
            System.Drawing.Bitmap destBmp = new Bitmap(srcBmp.Width, srcBmp.Height);
 
 
 
            // 将位图背景填充为白色 
 
            System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBmp);
 
            graph.FillRectangle(new SolidBrush(System.Drawing.Color.White), 0, 0, destBmp.Width, destBmp.Height);
 
            graph.Dispose();
 
 
 
            double dBaseAxisLen = bXDir ? (double)destBmp.Height : (double)destBmp.Width;
 
 
 
            for (int i = 0; i < destBmp.Width; i++)
            {
 
                for (int j = 0; j < destBmp.Height; j++)
                {
 
                    double dx = 0;
 
                    dx = bXDir ? (PI2 * (double)j) / dBaseAxisLen : (PI2 * (double)i) / dBaseAxisLen;
 
                    dx += dPhase;
 
                    double dy = Math.Sin(dx);
 
 
 
                    // 取得当前点的颜色 
 
                    int nOldX = 0, nOldY = 0;
 
                    nOldX = bXDir ? i + (int)(dy * dMultValue) : i;
 
                    nOldY = bXDir ? j : j + (int)(dy * dMultValue);
 
 
 
                    System.Drawing.Color color = srcBmp.GetPixel(i, j);
 
                    if (nOldX >= 0 && nOldX < destBmp.Width
 
                     && nOldY >= 0 && nOldY < destBmp.Height)
                    {
 
                        destBmp.SetPixel(nOldX, nOldY, color);
 
                    }
 
                }
 
            }
 
 
 
            return destBmp;
 
        }
 
        #endregion
 
        #region Public Methods
 
        public Stream CreateCheckCodeImage()
        {
 
            string checkCode;
 
            switch (_codetype)
            {
 
                case CodeType.Alphas:
 
                    checkCode = GenerateAlphas();
 
                    break;
 
                case CodeType.Numbers:
 
                    checkCode = GenerateNumbers();
 
                    break;
 
                case CodeType.Characters:
 
                    checkCode = GenerateCharacters();
 
                    break;
 
                default:
 
                    checkCode = GenerateAlphas();
 
                    break;
 
            }
 
            this._checkCode = checkCode;
 
            MemoryStream ms = null;
 
            // 
 
            if (checkCode == null || checkCode.Trim() == String.Empty)
 
                return null;
 
            Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * _jianju)), (int)_height);
 
            Graphics g = Graphics.FromImage(image);
 
            try
            {
 
                Random random = new Random();
 
                g.Clear(Color.White);
 
                // 画图片的背景噪音线 
 
                for (int i = 0; i < 18; i++)
                {
 
                    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.FromArgb(random.Next()), 1), x1, y1, x2, y2);
 
                }
 
                Font font = new System.Drawing.Font("Times New Roman", 14, System.Drawing.FontStyle.Bold);
 
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
 
                if (_codetype != CodeType.Words)
                {
 
                    for (int i = 0; i < checkCode.Length; i++)
                    {
 
                        g.DrawString(checkCode.Substring(i, 1), font, brush, 2 + i * _jianju, 1);
 
                    }
 
                }
                else
                {
 
                    g.DrawString(checkCode, font, brush, 2, 2);
 
                }
 
                // 画图片的前景噪音点 
 
                for (int i = 0; i < 150; i++)
                {
 
                    int x = random.Next(image.Width);
 
                    int y = random.Next(image.Height);
 
                    image.SetPixel(x, y, Color.FromArgb(random.Next()));
 
                }
 
                // 画图片的波形滤镜效果 
 
                if (_codetype != CodeType.Words)
                {
 
                    image = TwistImage(image, true, 3, 1);
 
                }
 
                // 画图片的边框线 
 
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
 
 
 
                ms = new System.IO.MemoryStream();
 
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
 
            }
 
            finally
            {
 
                g.Dispose();
 
                image.Dispose();
 
            }
 
            return ms;
 
        }
 
        #endregion
 
    }
 
}

    在form窗体中编写。

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 实验1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        ValidCode validCode = new ValidCode(5, ValidCode.CodeType.Numbers);//实例化这个对象
        private void Form1_Load(object sender, EventArgs e)
        {
           
            picValidCode.Image = Bitmap.FromStream(validCode.CreateCheckCodeImage());//加载验证码图片
        }
 
        private void button1_Click(object sender, EventArgs e)
        {
            if (!this.txtValidCode.Text.Equals(validCode.CheckCode))//验证是否输入正确
            {
 
                MessageBox.Show(" 请输入正确的验证码!", this.Text);
 
                this.txtValidCode.Focus();
                this.txtValidCode.Text = "";
 
                return;
 
            }
            else
            {
                MessageBox.Show("成功！");
            }
 
        }
 
        private void picValidCode_Click(object sender, EventArgs e)
        {
            picValidCode.Image = Bitmap.FromStream(validCode.CreateCheckCodeImage());//点击图片更换验证码
        }
    }
}