怎样用C#语言实现窗体验证码代码怎样写？

Question

  我想实现windows窗体上有验证码这一个事件用代码怎样实现啊  

Answer 1

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using Microsoft;namespace CheckCode
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        string checkCode = String.Empty;         private void Form1_Load(object sender, EventArgs e)
        {
            
            this.labelX1.Visible = false;
            this.pictureBox1.Visible = false;
            this.linkLabel1.Visible = false;
            this.textBoxX1.GotFocus += new EventHandler(textBox1_GotFocus);         
        }
        
        private Image CreateCheckCodeImage(string checkCode)
        {          
            if (checkCode == null || checkCode.Trim() == String.Empty)
                return null ;            System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 20.0)), 28);
            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 < 25; 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.Silver), x1, y1, x2, y2);
                }                Font font = new System.Drawing.Font("Arial", 18, (System.Drawing.FontStyle.Bold | System.Drawing.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);               // 画图片的前景噪音点 
                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()));
                }                //画图片的边框线 
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                System.IO.MemoryStream ms = new System.IO.MemoryStream();
                image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
               
                return image;                             
           
            }
            finally
            {
                //g.Dispose();
                //image.Dispose();
            }
        }
     
       private string GenerateCheckCode()
        {
           //得到随机文字
            int number;
            char code;
        
            System.Random random = new Random();            for (int i = 0; i < 5; i++)
            {
                number = random.Next();                if (number % 2 == 0)
                    code = (char)('0' + (char)(number % 10));
                else
                    code = (char)('A' + (char)(number % 26));                checkCode += code.ToString();
            }
            return checkCode;
        }       private void textBox1_GotFocus(object sender, EventArgs e) 
       {
           //首次得到焦点触发 显示验证文字         
           if (this.labelX1.Visible == false && this.pictureBox1.Visible == false && this.linkLabel1.Visible ==false)
           {
               checkCode = String.Empty;
               this.labelX1.Visible = true;
               this.pictureBox1.Visible = true;
               this.linkLabel1.Visible = true;               this.labelX1.Text = GenerateCheckCode();
               this.pictureBox1.Image = this.CreateCheckCodeImage(this.labelX1.Text);
           }
           else
           {           }                }
       private void buttonX1_Click(object sender, EventArgs e)
       {                  if (this.textBoxX1.Text.ToUpper().Trim()=="")
           {
               MessageBoxEx.Show("请输入验证码", "提示");
               checkCode = String.Empty;
               this.labelX1.Text = GenerateCheckCode();
               this.pictureBox1.Image = this.CreateCheckCodeImage(this.labelX1.Text);
               return;
           }
           if (this.textBoxX1.Text.ToUpper().Trim() !=checkCode)
           {
               MessageBoxEx.Show("验证码输入错误", "提示"); 
               checkCode = String.Empty;
               this.labelX1.Text = GenerateCheckCode();
               this.pictureBox1.Image = this.CreateCheckCodeImage(this.labelX1.Text);
               return;
           }
           else
           {
               MessageBoxEx.Show("验证信息正确", "提示");               
           }
           
       }       private void linkLabel1_LinkClicked(object sender, LinkLabelLinkClickedEventArgs e)
       {
           //看不清，换一张
           checkCode = String.Empty;
           this.labelX1.Text = GenerateCheckCode();
           this.pictureBox1.Image = this.CreateCheckCodeImage(this.labelX1.Text);       }
    }
}
//窗体中加上代码中出现的控件 textbox,picturebox,linklabel,label(可在代码中删掉)，button