帮助类

#region  生成验证码图片
public ActionResult SecurityCode()
{
    string code = CreateRandomCode(5);  //生成验证字符串
    TempData["SecurityCode"] = code;   //保存验证字符串
    return File(CreateValidateGraphic(code), "image/Jpeg");
}

/// <summary>
/// 生成随机的字符串
/// </summary>
[NonAction]
private string CreateRandomCode(int codeCount)
{
    string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z";
    string[] allCharArray = allChar.Split(‘,‘);
    string randomCode = "";
    int temp = -1;
    Random rand = new Random();
    for (int i = 0; i < codeCount; i++)
    {
        if (temp != -1)
        {
            rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
        }
        int t = rand.Next(35);
        if (temp == t)
        {
            return CreateRandomCode(codeCount);
        }
        temp = t;
        randomCode += allCharArray[t];
    }
    return randomCode;
}
/// <summary>
/// 创建验证码的图片
/// </summary>
[NonAction]
public byte[] CreateValidateGraphic(string validateCode)
{
    Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 16.0), 27);
    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", 13, (FontStyle.Bold | FontStyle.Italic));
        LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
         Color.Blue, Color.DarkRed, 1.2f, 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();
    }
}
#endregion

前台调用

  <% using (Html.BeginForm("Register", "Account", FormMethod.Post, new { id = "Form1", @class = "member_form" }))
            { %>


        <p>
            <label><span>*</span>用户名</label>
            <%=Html.TextBox("LoginId", null, new { @class="opt_input" })%>
            <%=Html.ValidationMessage("LoginId")%>
        </p>
        <p>
            <label><span>*</span>真实姓名</label>
            <%=Html.TextBox("Name", null, new  {@class="opt_input" })%>
        </p>
        <p>
            <label><span>*</span>密码</label>
            <%=Html.Password("LoginPwd",null, new { @class="opt_input"})%>
            <%=Html.ValidationMessage("LoginPwd")%>
        </p>
        <p>
            <label><span>*</span>确认密码</label><input class="opt_input" name="PasswordConfirm" type="password" value="<%=Model != null ? Model.PasswordConfirm : ""%>" />
            <%=Html.ValidationMessage("PasswordConfirm")%>
        </p>
        <p>
            <label><span>*</span>电子邮件</label><input class="opt_input" name="Mail" type="text" value="<%= Model != null ? Model.Mail : ""%>" />
            <%=Html.ValidationMessage("Mail")%>
        </p>
        <p>
            <label><span>*</span>地址</label><input class="opt_input" name="Address" type="text" />
        </p>
        <p>
            <label><span>*</span>手机</label><input class="opt_input" name="Phone" type="text" />
        </p>

        <p>
            <label><span>*</span>验证码</label>
            <%-- securityCode要与注册Register方法参数名称一致 --%>
            <input name="securityCode" type="text" class="opt_input" />
            <img alt="验证码图片" id="ImgValidateCode" title="看不清？点击换一个"
                src="<%=Url.Action("SecurityCode","Account") %>" onclick="this.src=this.src+‘?‘" />
            <%=Html.ValidationMessage("securityCode") %>
        </p>

        <p class="form_sub">
            <input type="submit" value="确定了，马上提交" class="opt_sub" />
            <%=Html.Submit("register","确定了，马上提交") %>
        </p>
        <p class="form_sub">加<span>*</span>的为必填项目</p>
        <p class="form_sub">
            ><a href="login.html">已经有账号，马上登录</a><br />
            >已有账号 <%= Html.ActionLink("点这里", "LogIn", "Account")%>登录
        </p>


        <%} %>

Asp.net 验证码

原文：https://www.cnblogs.com/qzdd/p/13550710.html