asp.net登录验证码实现方法

$(function () {
      $("#imgValidateCode").click(function () {
        DoFresh();
      });
      DoFresh();
    })
function DoFresh() {
      var img = $("#imgValidateCode");
      img.attr("src", "VerifyCode.aspx&＃63;random=" + Math.random());

    } //添加的方法，src是生成图片的aspx的地址 

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="VerifyCode.aspx.cs" Inherits="Form.VerifyCode" %> 


 

   

 
 
   
   

   
  
   

 
  

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

using System.Drawing;

 

namespace Form
{
  public partial class VerifyCode : System.Web.UI.Page
  {
    public static string HZ;
    /// 

    /// 验证码的最大长度
    /// 
    public int MaxLength
    {
      get { return 10; }

    }
    /// 

    /// 验证码的最小长度
    /// 
    public int MinLength
    {
      get { return 1; }
    }
 
    protected void Page_Load(object sender, EventArgs e)
    {
      string[] str = CreateValidateNumber(4);
      string strcode = string.Empty;
      for (int i = 0; i 
    /// 生成验证码
    /// 
    /// 指定验证码的长度
    /// 验证码
    public string[] CreateValidateNumber(int length)

    {
      string Vchar = "1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,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,P,Q" +
      ",R,S,T,U,V,W,X,Y,Z";

      string[] VcArray = Vchar.Split(new Char[] { ',' });//拆分成数组
       string[] num = new string[length];

      int temp = -1;//记录上次随机数值，尽量避避免生产几个一样的随机数

     Random rand = new Random();

      //采用一个简单的算法以保证生成随机数的不同

      for (int i = 1; i