ASP.NET MVC3实现无刷新验证码

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>