图片添加水印和生成验证码

一、生成验证码：直接看代码

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Web;


namespace Common
{
    public class ValidateCode
    {
        public ValidateCode()
        {
        }
        /// <summary>
        /// 验证码的最大长度
        /// </summary>
        public int MaxLength
        {
            get { return 10; }
        }
        /// <summary>
        /// 验证码的最小长度
        /// </summary>
        public int MinLength
        {
            get { return 1; }
        }
        /// <summary>
        /// 生成验证码
        /// </summary>
        /// <param name="length">指定验证码的长度</param>
        /// <returns></returns>
        public string CreateValidateCode(int length)
        {
            int[] randMembers = new int[length];
            int[] validateNums = new int[length];
            string validateNumberStr = "";
            //生成起始序列值
            int seekSeek = unchecked((int)DateTime.Now.Ticks);
            Random seekRand = new Random(seekSeek);
            int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
            int[] seeks = new int[length];
            for (int i = 0; i < length; i++)
            {
                beginSeek += 10000;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for (int i = 0; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum = 1 * (int)Math.Pow(10, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for (int i = 0; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(0, numLength - 1);
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
            }
            //生成验证码
            for (int i = 0; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return validateNumberStr;
        }
        /// <summary>
        /// 创建验证码的图片
        /// </summary>
        /// <param name="context">要输出到的page对象</param>
        /// <param name="validateNum">验证码</param>
        public void CreateValidateGraphic(string validateCode, HttpContext context)      //使用HttpContext必须引用system.web，是引入而不是导入
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 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);
                //画图片的干扰线
                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 Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(validateCode, font, brush, 3, 2);
                //画图片的前景干扰点
                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);
                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //输出图片流
                context.Response.Clear();
                context.Response.ContentType = "image/jpeg";
                context.Response.BinaryWrite(stream.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
        /// <summary>
        /// 得到验证码图片的长度
        /// </summary>
        /// <param name="validateNumLength">验证码的长度</param>
        /// <returns></returns>
        public static int GetImageWidth(int validateNumLength)
        {
            return (int)(validateNumLength * 12.0);
        }
        /// <summary>
        /// 得到验证码的高度
        /// </summary>
        /// <returns></returns>
        public static double GetImageHeight()
        {
            return 22.5;
        }



        //C# MVC 升级版
        /// <summary>
        /// 创建验证码的图片
        /// </summary>
        /// <param name="containsPage">要输出到的page对象</param>
        /// <param name="validateNum">验证码</param>
        public byte[] CreateValidateGraphic(string validateCode)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 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);
                //画图片的干扰线
                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 Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(validateCode, font, brush, 3, 2);
                //画图片的前景干扰点
                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);
                //保存图片数据
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //输出图片流
                return stream.ToArray();
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
    }
}

这是前端验证码的表单

 <tr>
                                <td width="24%" height="26" align="right" valign="top">
                                    验证码：
                                </td>
                                <td valign="top" width="37%" align="left">
                                    <input type="text" name="vCode" />&nbsp;
                                </td>
                                <td align="left">
                                    <img id="img" src="/Login/ShowValidateCode?id=1" style="float: left; height: 24px;" />&nbsp;
                                    <a href="javascript:void(0)" onclick="changeCheckCode();return false;">看不清，换一张</a>
                                </td>
                                <td align="left">
                                    <div style="float: left;">
                                        
                                    </div>
                                </td>
                            </tr>

其中点击需要触发该事件，目的是为了让cookie的key值不相同

 function changeCheckCode() {
            $("#img").attr("src", $("#img").attr("src") + 1);
        }

然后调用该控制器的方法，该方法各处的验证码都可以调用

   #region 显示验证码
        public ActionResult ShowValidateCode()
        {
            Common.ValidateCode vliateCode = new Common.ValidateCode();
            string code = vliateCode.CreateValidateCode(4);//产生验证码
            Session["validateCode"] = code;
            byte[] buffer = vliateCode.CreateValidateGraphic(code);//将验证码画到画布上.
            return File(buffer, "image/jpeg");
        }
        #endregion

最终的值传递给该方法

 [HttpPost]
        //public JsonResult RegisterUser()
        public ActionResult RegisterUser()
        {
            JsonResult json = new JsonResult();
            string validateCode = Session["validateCode"] != null ? Session["validateCode"].ToString() : string.Empty;
            if (string.IsNullOrEmpty(validateCode))
            {
                //json.Data = new { success = false, msg = "验证码错误" };
                //return json;
                return Content("no:验证码错误!!");
            }
            Session["validateCode"] = null;
            string txtCode = Request["vCode"];
            if (!validateCode.Equals(txtCode, StringComparison.InvariantCultureIgnoreCase))
            {
                //json.Data = new { success = false, msg = "验证码错误" };
                //return json;
                return Content("no:验证码错误!!");
            }
            string userName = Request["UserName"];
            var userInfo = UserInfoService.LoadEntities(u => u.UName == userName).FirstOrDefault();//根据用户名找用户
            if (userInfo != null)
            {
                //json.Data = new { success = false, msg = "该账号已存在" };
                //return json;
                return Content("no:该账号已存在");
            }
            else 
            {
                //json.Data = new { success = false, msg = "注册成功" };
                //return json;
                return Content("ok:注册成功");
            }

        }