MVC中的验证码

public class CodeController : Controller
{
private const string CODE = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//验证码字符池
private const int COUNT = 6;//验证码字符个数
private const int WIDTH = 80;//图片宽
private const int HEIGHT = 20;//图片高

// 产生验证码
private string GetCode()
{
Random r = new Random();
int length = CODE.Length;
StringBuilder sCode = new StringBuilder();
for (int i = 0; i < COUNT; i++)
{
int index = r.Next(0, length);
sCode.Append(CODE[index]);
}
return sCode.ToString();
}

/// <summary>
/// 创建验证码图片
/// </summary>
/// <returns>图片文件</returns>
public ActionResult Code()
{
//画背景图
Bitmap bmp = new Bitmap(WIDTH, HEIGHT);//创建位图(宽，高)
Graphics g = Graphics.FromImage(bmp);//创建画布
g.FillRectangle(Brushes.LightGray, 0, 0, WIDTH, HEIGHT);//为画布填充底色(颜色，起始位置，终止位置)

//画验证码
string code = this.GetCode();//取出验证码
this.Session.Add("code", code);//将当前验证码存入Session
Font f = new Font("微软雅黑", 12, FontStyle.Italic);//自定义文本格式(字体，字号，字形)
g.DrawString(code, f, Brushes.Black, 0, 0);//在画布上写入文本(内容，格式，颜色，起始位置)

//画干扰点或线
Random r = new Random();
for (int i = 0; i < 50; i++)
{
Color color = Color.FromArgb(r.Next(0, 256), r.Next(0, 256), r.Next(0, 256));//随机颜色
Pen pen = new Pen(color);//创建线笔(颜色)

int x = r.Next(0, WIDTH);
int y = r.Next(0, HEIGHT);
int xDir = r.Next(3);
int yDir = r.Next(3);
g.DrawLine(pen, x, y, x + xDir, y + yDir);//在画布上画短线(线笔，起始位置，终止位置)
}
ReturnResult result = new ReturnResult() { Result=true};
//向客户端输出
using (MemoryStream mStream = new MemoryStream())//创建内存流对象
{
bmp.Save(mStream, ImageFormat.Jpeg);//保存位图至内存流(内存流，格式)
byte[] data = mStream.ToArray();//将内存流转换成字节数组
return this.File(data, "application/image");//向客户端输出文件(输出内容，内容类型)
}
}

}

<div class="Mask_div1 clearfix">
<p class="Mask_p1 fl">验证码：</p>
<input type="text" class="Mask_text1 fl" id="codetxt" />
<img src="/code/code" id="code" class="Mask_ing fl" />
<a href="javascript:void(0)" id="change" class="Mask_a1 fl">【刷新】</a>
</div>

<script>
$(function(){
$("#change").click(function () {
var url = "/code/code?t=" + Date();
$("#code").attr("src", url);
});

})
</script>