html部分：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<table>
<tr>
<td><img id="validImg" src="/Login/CheckCode?ID=1" alt="点我刷新" onclick="changeValidCode()"></td>
<td><a href="#" onclick="changeValidCode()">点我刷新</a></td>
</tr>
</table> <script >
$(function(){
function changeValidCode(){
var code=$("#validImg").attr('src');
$("#validImg").attr("src", code + "1");
}
})
</script>
</body>
</html>
asp.net mvc返回文件地址：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc; namespace MyDemo.Controllers
{
public class LoginController : Controller
{ /// <summary>
/// 用户登录验证码
/// </summary>
/// <returns></returns>
public ActionResult CheckCode()
{ ValidateCode vCode = new ValidateCode();
string code = vCode.CreateValidateCode();
Session["SysValidateCode"] = code;
byte[] bytes = vCode.CreateValidateGraphic(code);
return File(bytes, @"image/jpeg");
} }
}
验证码生成类：
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; namespace MyDemo.Model
{
/// <summary>
/// 生成验证码的类
/// </summary>
public class ValidateCode
{
public ValidateCode()
{
}
/// <summary>
/// 验证码的最大长度
/// </summary>
public int MaxLength
{
get { return ; }
}
/// <summary>
/// 验证码的最小长度
/// </summary>
public int MinLength
{
get { return ; }
}
/// <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(, Int32.MaxValue - length * );
int[] seeks = new int[length];
for (int i = ; i < length; i++)
{
beginSeek += ;
seeks[i] = beginSeek;
}
//生成随机数字
for (int i = ; i < length; i++)
{
Random rand = new Random(seeks[i]);
int pownum = * (int)Math.Pow(, length);
randMembers[i] = rand.Next(pownum, Int32.MaxValue);
}
//抽取随机数字
for (int i = ; i < length; i++)
{
string numStr = randMembers[i].ToString();
int numLength = numStr.Length;
Random rand = new Random();
int numPosition = rand.Next(, numLength - );
validateNums[i] = Int32.Parse(numStr.Substring(numPosition, ));
}
//生成验证码
for (int i = ; 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 * 16.0), );
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 = ; i < ; 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", , (FontStyle.Bold | FontStyle.Italic));
LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(, , image.Width, image.Height),
Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(validateCode, font, brush, , );
//画图片的前景干扰点
for (int i = ; i < ; 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), , , image.Width - , image.Height - );
//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();
}
}
/// <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 * 16.0);
}
/// <summary>
/// 得到验证码的高度
/// </summary>
/// <returns></returns>
public static double GetImageHeight()
{
return ;
}
}
}