爱上MVC3系列~无刷新验证码

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在MVC中进行留言，评论等功能时，不可避免会用到表单提交时的验证码问题，有时，我们的作法是，当表单被提交后，在controller里去判断验证码的正确与否，但我认为这种用户体验是很差的，今天正好有后时间，把这方法的东西总结一下：

首先，在公用项目中建立一个生成图片验证码的类型ValidateCode，代码如下：

  1   /// <summary>
  2   /// 生成验证码对象
  3   /// </summary>
  4   public class ValidateCode
  5   {
  6     public ValidateCode()
  7     {
  8     }
  9     ///<summary>
 10     /// 验证码的最大长度
 11     ///</summary>
 12     public int MaxLength
 13     {
 14       get { return 10; }
 15     }
 16     ///<summary>
 17     /// 验证码的最小长度
 18     ///</summary>
 19     public int MinLength
 20     {
 21       get { return 1; }
 22     }
 23     ///<summary>
 24     /// 生成验证码
 25     ///</summary>
 26     ///<param name="length">指定验证码的长度</param>
 27     ///<returns></returns>
 28     public string CreateValidateCode(int length)
 29     {
 30       int[] randMembers = new int[length];
 31       int[] validateNums = new int[length];
 32       string validateNumberStr = "";
 33       //生成起始序列值
 34       int seekSeek = unchecked((int)DateTime.Now.Ticks);
 35       Random seekRand = new Random(seekSeek);
 36       int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
 37       int[] seeks = new int[length];
 38       for (int i = 0; i < length; i++)
 39       {
 40         beginSeek += 10000;
 41         seeks[i] = beginSeek;
 42       }
 43       //生成随机数字
 44       for (int i = 0; i < length; i++)
 45       {
 46         Random rand = new Random(seeks[i]);
 47         int pownum = 1 * (int)Math.Pow(10, length);
 48         randMembers[i] = rand.Next(pownum, Int32.MaxValue);
 49       }
 50       //抽取随机数字
 51       for (int i = 0; i < length; i++)
 52       {
 53         string numStr = randMembers[i].ToString();
 54         int numLength = numStr.Length;
 55         Random rand = new Random();
 56         int numPosition = rand.Next(0, numLength - 1);
 57         validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
 58       }
 59       //生成验证码
 60       for (int i = 0; i < length; i++)
 61       {
 62         validateNumberStr += validateNums[i].ToString();
 63       }
 64       return validateNumberStr;
 65     }
 66     ///<summary>
 67     /// 创建验证码的图片
 68     ///</summary>
 69     ///<param name="containsPage">要输出到的page对象</param>
 70     ///<param name="validateNum">验证码</param>
 71     public byte[] CreateValidateGraphic(string validateCode)
 72     {
 73       Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 14.0), 22);
 74       Graphics g = Graphics.FromImage(image);
 75       try
 76       {
 77         //生成随机生成器
 78         Random random = new Random();
 79         //清空图片背景色
 80         g.Clear(Color.White);
 81         //画图片的干扰线
 82         for (int i = 0; i < 25; i++)
 83         {
 84           int x1 = random.Next(image.Width);
 85           int x2 = random.Next(image.Width);
 86           int y1 = random.Next(image.Height);
 87           int y2 = random.Next(image.Height);
 88           g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
 89         }
 90         Font font = new Font("Arial", 14, (FontStyle.Bold | FontStyle.Italic));
 91         LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
 92         Color.Blue, Color.DarkRed, 1.5f, true);
 93         g.DrawString(validateCode, font, brush, 3, 2);
 94         //画图片的前景干扰点
 95         for (int i = 0; i < 100; i++)
 96         {
 97           int x = random.Next(image.Width);
 98           int y = random.Next(image.Height);
 99           image.SetPixel(x, y, Color.FromArgb(random.Next()));
100         }
101         //画图片的边框线
102         g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
103         //保存图片数据
104         MemoryStream stream = new MemoryStream();
105         image.Save(stream, ImageFormat.Jpeg);
106         //输出图片流
107         return stream.ToArray();
108       }
109       finally
110       {
111         g.Dispose();
112         image.Dispose();
113       }
114     }
115   }

然后，在当前公用的controller中添加一个返回文件类型的action,当然也可以是所有返回类型的基类ActionResult，这个方法用来返回一个图像对象

 1     /// <summary>
 2     /// 生成验证码图像对象
 3     /// </summary>
 4     /// <returns></returns>
 5     public ActionResult GetValidateCode()
 6     {
 7       ValidateCode vCode = new ValidateCode();
 8       string code = vCode.CreateValidateCode(4);
 9       Session["ValidateCode"] = code;
10       byte[] bytes = vCode.CreateValidateGraphic(code);
11       return File(bytes, @"image/jpeg");
12     }

再次，需要我们写一个返回当前验证吗的方法，这是作无刷新验证码的关键

1     /// <summary>
2     /// 得到当前验证码
3     /// </summary>
4     /// <returns></returns>
5     public ActionResult GetCurrentValidateCode()
6     {
7       return Content(Session["ValidateCode"].ToString());
8     }

最后，就是页面上的事了，看代码：

 1              <div id="ValidateCodeSpan">
 2                     请输入验证码：@Html.TextBox("VCode")
 3                     <img id="valiCode" style="cursor: pointer;" src="/Common/GetValidateCode" alt="看不清？请点我" />
 4                     @Html.Hidden("ValidateCode")
 5                     <script type="text/javascript">
 6                         $(function () {
 7                             //首次加载
 8                             $("#valiCode").attr("src","/Common/GetValidateCode?time=" + (new Date()).getTime());
 9                             $.get("/Common/GetCurrentValidateCode", function (data) {
10                                 $("#ValidateCode").val(data);
11                             });
12                             //单击验证码事件
13                             $("#valiCode").bind("click", function () {
14                                 this.src = "/Common/GetValidateCode?time=" + (new Date()).getTime();
15                                 $.get("/Common/GetCurrentValidateCode", function (data) {
16                                     $("#ValidateCode").val(data);
17                                 });
18                             });
19                         });
20                     </script>
21                 </div>

 

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