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：

  /// <summary>
  /// 生成验证码对象
  /// </summary>
  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="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 * 14.0), 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", 14, (FontStyle.Bold | FontStyle.Italic));
        LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
        Color.Blue, Color.DarkRed, 1.5f, 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();
      }
    }
  }

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

    /// <summary>
    /// 生成验证码图像对象
    /// </summary>
    /// <returns></returns>
    public ActionResult GetValidateCode()
    {
      ValidateCode vCode = new ValidateCode();
      string code = vCode.CreateValidateCode(4);
      Session["ValidateCode"] = code;
      byte[] bytes = vCode.CreateValidateGraphic(code);
      return File(bytes, @"image/jpeg");
    }

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

    /// <summary>
    /// 得到当前验证码
    /// </summary>
    /// <returns></returns>
    public ActionResult GetCurrentValidateCode()
    {
      return Content(Session["ValidateCode"].ToString());
    }

最后，就是页面上的事了，看代码：

             <div id="ValidateCodeSpan">
                    请输入验证码：@Html.TextBox("VCode")
                    <img id="valiCode" style="cursor: pointer;" src="/Common/GetValidateCode" alt="看不清？请点我" />
                    @Html.Hidden("ValidateCode")
                    <script type="text/javascript">
                        $(function () {
                            //首次加载
                            $("#valiCode").attr("src","/Common/GetValidateCode?time=" + (new Date()).getTime());
                            $.get("/Common/GetCurrentValidateCode", function (data) {
                                $("#ValidateCode").val(data);
                            });
                            //单击验证码事件
                            $("#valiCode").bind("click", function () {
                                this.src = "/Common/GetValidateCode?time=" + (new Date()).getTime();
                                $.get("/Common/GetCurrentValidateCode", function (data) {
                                    $("#ValidateCode").val(data);
                                });
                            });
                        });
                    </script>
                </div>

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