C# 生成验证码图片

System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Drawing;
using System.Drawing.Drawing2D; 

namespace FreeOH.Validate
{
    /// <summary>
    /// 本类用于产生随机的验证码
    /// </summary>
    public class ValidationCode
    {
        //用户存取验证码字符串
        public string validationCode = String.Empty; 

        Graphics g = null; 

        int bgWidth = 0;
        int bgHeight = 0; 

        public string FontFace = "Comic Sans MS";
        public int FontSize = 9;
        public Color foreColor = Color.FromArgb(220, 220, 220);
        public Color backColor = Color.FromArgb(190, 190, 190);
        public Color mixedLineColor = Color.FromArgb(220, 220, 220);
        public int mixedLineWidth = 1;
        public int mixedLineCount = 5; 


        #region 根据指定长度，返回随机验证码
        /// <summary>
        /// 根据指定长度，返回随机验证码
        /// </summary>
        /// <param name="length">制定长度</param>
        /// <returns>随即验证码</returns>
        public string Next(int length)
        {
            this.validationCode = GetRandomCode(length);
            return this.validationCode;
        }
        #endregion 


        #region 根据指定长度及背景图片样式，返回带有随机验证码的图片对象
        /// <summary>
        /// 根据指定长度及背景图片样式，返回带有随机验证码的图片对象
        /// </summary>
        /// <param name="length">指定长度</param>
        /// <param name="hatchStyle">背景图片样式</param>
        /// <returns>Image对象</returns>
        public Image NextImage(int length, HatchStyle hatchStyle, bool allowMixedLines)
        {
            this.validationCode = GetRandomCode(length); 

            //校验码字体
            Font myFont = new Font(FontFace, FontSize); 

            //根据校验码字体大小算出背景大小
            bgWidth = (int)myFont.Size * length + 4;
            bgHeight = (int)myFont.Size * 2;
            //生成背景图片
            Bitmap myBitmap = new Bitmap(bgWidth, bgHeight); 

            g = Graphics.FromImage(myBitmap); 


            this.DrawBackground(hatchStyle);
            this.DrawValidationCode(this.validationCode,myFont);
            if (allowMixedLines)
                this.DrawMixedLine(); 

            return (Image)myBitmap;
        }
        #endregion 


        #region 内部方法：绘制验证码背景
        private void DrawBackground(HatchStyle hatchStyle)
        {
            //设置填充背景时用的笔刷
            HatchBrush hBrush = new HatchBrush(hatchStyle, backColor); 

            //填充背景图片
            g.FillRectangle(hBrush, 0, 0, this.bgWidth, this.bgHeight);
        }
        #endregion 


        #region 内部方法：绘制验证码
        private void DrawValidationCode(string vCode, Font font)
        {
            g.DrawString(vCode, font, new SolidBrush(this.foreColor), 2, 2);
        }
        #endregion 


        #region 内部方法：绘制干扰线条
        /// <summary>
        /// 绘制干扰线条
        /// </summary>
        private void DrawMixedLine()
        {
            for (int i = 0; i < mixedLineCount; i++)
            {
                g.DrawBezier(new Pen(new SolidBrush(mixedLineColor), mixedLineWidth), RandomPoint(), RandomPoint(), RandomPoint(), RandomPoint());
            }
        }
        #endregion 

        #region 内部方法：返回指定长度的随机验证码字符串
        /// <summary>
        /// 根据指定大小返回随机验证码
        /// </summary>
        /// <param name="length">字符串长度</param>
        /// <returns>随机字符串</returns>
        private string GetRandomCode(int length)
        {
            StringBuilder sb = new StringBuilder(6); 

            for (int i = 0; i < length; i++)
            {
                sb.Append(Char.ConvertFromUtf32(RandomAZ09()));
            } 

            return sb.ToString();
        }
        #endregion 


        #region 内部方法：产生随机数和随机点 

        /// <summary>
        /// 产生0-9A-Z的随机字符代码
        /// </summary>
        /// <returns>字符代码</returns>
        private int RandomAZ09()
        {
            Thread.Sleep(15);
            int result = 48;
            Random ram = new Random();
            int i = ram.Next(2); 

            switch (i)
            {
                case 0:
                    result = ram.Next(48, 58);
                    break;
                case 1:
                    result = ram.Next(65, 91);
                    break;
            } 

            return result;
        } 

        /// <summary>
        /// 返回一个随机点，该随机点范围在验证码背景大小范围内
        /// </summary>
        /// <returns>Point对象</returns>
        private Point RandomPoint()
        {
            Thread.Sleep(15);
            Random ram = new Random();
            Point point = new Point(ram.Next(this.bgWidth), ram.Next(this.bgHeight));
            return point;
        }
        #endregion
    }
}

 

把图片输入到页面

    System.IO.MemoryStream ms = new System.IO.MemoryStream();
    image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
    System.Web.HttpContext.Current.Response.ClearContent();
    System.Web.HttpContext.Current.Response.ContentType = "image/Gif";
    System.Web.HttpContext.Current.Response.BinaryWrite(ms.ToArray());

生成验证码 点击可刷新

先建一张生成验证码的网页CheckCode.aspx:CheckCode.aspx.cs代码如下添加引用:using System.IO;using System.Drawing;using System.Drawing.Imaging;using System.Drawing.Drawing2D;然后是显示验证码的页面 的html中加入<img src="Default2.aspx" id="yzm" alt="点击刷新" />在</head>之前一行加入javascript脚本语言如下(当然写在JS文件里面更好):<script type="text/javascript">function reloadcode(){ document.getElementById("yzm").src ="CheckCode.aspx";}