asp.net登录时生成验证码的方法

浏览数：52 / 时间：2015年06月09日

在CommonClass.cs中定义RandomNum(4)的方法：

    /// <summary>
    /// 实现随机验证码
    /// </summary>
    /// <param name="n">验证码个数</param>
    /// <returns>返回生成的随机数</returns>
    public string RandomNum(int n) {
        string strchar = "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,V,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z";
        string[] VcArray = strchar.Split(',');
        string VNum = "";
        int temp = -1;
        Random rand=new Random();
        for (int i=1; i < n + 1; i++) {
            if (temp != -1) {
                rand = new Random(i*temp*unchecked((int)DateTime.Now.Ticks));
            }
            int t = rand.Next(61);
            if (temp != -1 && temp == t) {
                return RandomNum(n);
            
            }
            temp = t;
            VNum += VcArray[t];
        }
        return VNum;
    
    
    }

.aspx代码如下：

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Login.aspx.cs" Inherits="Login" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<style type="text/css">
.tbl_login{ padding:10px; margin:10px;}
.tbl_login td{ padding:10px; border:1px solid gray;}
</style>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:Table ID="Table1" runat="server" CssClass="tbl_login">
<asp:TableRow runat="server">
<asp:TableCell>管理员姓名：</asp:TableCell>
<asp:TableCell><asp:TextBox ID="TextBox1" runat="server"></asp:TextBox></asp:TableCell>
</asp:TableRow>
<asp:TableRow runat="server">
<asp:TableCell>管理员密码：</asp:TableCell>
<asp:TableCell><asp:TextBox ID="TextBox2" runat="server" TextMode="Password"></asp:TextBox></asp:TableCell>
</asp:TableRow>
<asp:TableRow ID="TableRow1" runat="server">
<asp:TableCell>验证码：</asp:TableCell>
<asp:TableCell><asp:TextBox ID="TextBox3" runat="server" ></asp:TextBox></asp:TableCell>
<asp:TableCell style="border:1px solid silver;">
<asp:Label ID="lab_Code" runat="server" Text="8888"></asp:Label></asp:TableCell>
</asp:TableRow>
<asp:TableRow runat="server">
<asp:TableCell>
<asp:Button ID="btn_login" runat="server" Text="登录" /></asp:TableCell>
<asp:TableCell>
<asp:Button ID="btn_cancel" runat="server" Text="取消" /></asp:TableCell>
</asp:TableRow>

</asp:Table>
</div>
</form>
</body>
</html>

.aspx.cs代码如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class Login : System.Web.UI.Page
{
    CommonClass cc = new CommonClass();
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack) {
            this.lab_Code.Text = cc.RandomNum(4);
        
        }
    }

}

效果如下：