AJAX验证码无刷新的问题？

bo523 2010-01-21 05:06:13

大家看看我的这段代码，为什么我点击“看不清楚换一张”没效果啊，验证码图片不更换？我如果把LinkButton1放到UpdatePanel的外面又有回发了



 <form id="form1" runat="server">

    <asp:ScriptManager ID="ScriptManager1" runat="server">

    </asp:ScriptManager>

    

    <asp:UpdatePanel ID="UpdatePanel1" runat="server">

          <ContentTemplate>

            <div>

               <img src="a.ashx"  alt=""/>

            </div>

          <asp:LinkButton ID="LinkButton1" runat="server">看不清楚换一张</asp:LinkButton>

          </ContentTemplate>

    </asp:UpdatePanel>

    </form>

...全文

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人到中年琐事多 2010-01-21

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赞同楼主采用ajax
要真正刷新就要避免读取到缓存的内容，最简单的办法是每次请求的ＵＲＬ不相同，加一个时间或者随机数
另一种办法是用一大堆Ｈｅａｄｅｒ的属性指定不要缓存，比较繁琐

小_虎 2010-01-21

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我一般的做法，是直接在img上加一个js的onclick事件。
事件onclick="this.src=this.src+'?'"

以专业开发人员为伍 2010-01-21

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另外，很重要很重要地，你的img的src后边最好/应该有一个随机数字，例如：a.aspx?238223848324832。每一次回发，应该动态产生不同的数字。如果你改变不了他就加上runat=server变为服务器控件。

以专业开发人员为伍 2010-01-21

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[Quote=引用楼主 bo523 的回复:]
大家看看我的这段代码，为什么我点击“看不清楚换一张”没效果啊，验证码图片不更换？我如果把LinkButton1放到UpdatePanel的外面又有回发了

C# code<form id="form1" runat="server"><asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager><asp:UpdatePanel ID="UpdatePanel1" runat="server"><ContentTemplate><div><img src="a.ashx" alt=""/></div><asp:LinkButton ID="LinkButton1" runat="server">看不清楚换一张</asp:LinkButton></ContentTemplate></asp:UpdatePanel></form>
[/Quote]

为你的LinkButton1注册一个OnClick，即使它在后台什么也不做（空函数），也要写。

chen_ya_ping 2010-01-21

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你可以试试用其他的AJAX方案

80后大叔爱学习 2010-01-21

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[Quote=引用 7 楼 houdilzc 的回复:]
我的验证码全部用的这个呵呵直接拿去就可以用了
[/Quote]
你写的是数字的验证码，你把注释掉的去掉，有几率会出现标点符号
if (number % 2 == 0)
code = (char)('0' + (char)(number % 10));
else
code = (char)('A' + (char)(number % 26));

戒烟戒酒戒编程 2010-01-21

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一定需要把linkbutton放在updatepanel外面才能出发它的autopostback

houdilzc 2010-01-21

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我的验证码全部用的这个呵呵直接拿去就可以用了

houdilzc 2010-01-21

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<img alt="验证码" src="ValidateCode.aspx" id="validate" onclick="javascript:document.getElementById('validate').src='ValidateCode.aspx?'+new Date;" />

ValidateCode.aspx:



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



<!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>验证码</title>

    <% Response.Buffer = true ;%> 

    <% Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);%> 

    <% Response.Expires = 0 ;%> 

    <% Response.CacheControl = "no-cache" ; %>

</head>

<body>

    <form id="form1" runat="server">

    <div>

    

    </div>

    </form>

</body>

</html>

ValidateCode.aspx.cs:





using System;

using System.Collections;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Web;

using System.Web.SessionState;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.HtmlControls;  



public partial class ValidateCode : BasePageHelper

{

    /// <summary>

    /// 开始

    /// </summary>

    /// <param name="sender"></param>

    /// <param name="e"></param>

    protected void Page_Load(object sender, EventArgs e)

    {

        this.setCheckCode(2);

    }



    /// <summary>

    ///  设置验证码

    /// </summary>

    /// <param name="i">验证的方式</param>

    public void setCheckCode(int i)

    {



        if (i == 1)

        {

            // 此种方式的获取使用 Session["CheckCode"]

            string checkCode = CreateRandomCode(5);

            Session["CheckCode"] = checkCode;

            CreateImage(checkCode);

        }

        else if (i == 2)

        {

            //  此种方式的获取使用 Request.Cookies["CheckCode"]

            //

            //  在CheckCode.aspx的html的<head></head>中加入以下代码，后退验证码会刷新。 

            //  <% Response.Buffer = true ;%> 

            //  <% Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);%> 

            //  <% Response.Expires = 0 ;%> 

            //  <% Response.CacheControl = "no-cache" ; %>

            string checkCode = GenerateCheckCode();

            Session["CheckCode"] = checkCode;

            this.CreateCheckCodeImage(checkCode);

        }

    }



    /// <summary>

    /// 产生随机码

    /// </summary>

    /// <param name="codeCount">验证码位数</param>

    /// <returns>返回随机码</returns>

    private string CreateRandomCode(int codeCount)

    {

        string strNumberic = "", strUchar = "", strLchar = "", allChar = "";

        strNumberic = "0,1,2,3,4,5,6,7,8,9";

        strUchar = strNumberic;

        strLchar = strNumberic;

        allChar = strNumberic + "," + strUchar + "," + strLchar;

        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(30);

            if (temp == t)

            {

                return CreateRandomCode(codeCount);

            }

            temp = t;

            randomCode += allCharArray[t];

        }

        return randomCode;

    }



    /// <summary>

    /// 根据获得的随机密码生成图片形式

    /// </summary>

    /// <param name="checkCode">随机密码</param>

    private void CreateImage(string checkCode)

    {

        int iwidth = (int)(checkCode.Length * 11.5);

        System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);

        Graphics g = Graphics.FromImage(image);

        Font f = new System.Drawing.Font("Arial", 10, System.Drawing.FontStyle.Bold);

        Brush b = new System.Drawing.SolidBrush(Color.White);



        // 改变生成图片的背景颜色

        g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);

        //g.Clear(Color.YellowGreen);

        g.DrawString(checkCode, f, b, 3, 3);



        Pen blackPen = new Pen(Color.AntiqueWhite, 0);

        Random rand = new Random();



        // 生成随机的水平线

        for (int i = 0; i < 2; i++)

        {

            int y = rand.Next(image.Height);

            g.DrawLine(blackPen, 0, y, image.Width, y);

        }



        System.IO.MemoryStream ms = new System.IO.MemoryStream();

        image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);

        Response.ClearContent();

        Response.ContentType = "image/Jpeg";

        Response.BinaryWrite(ms.ToArray());

        g.Dispose();

        image.Dispose();

    }







    private string GenerateCheckCode()

    {

        int number;

        char code;

        string checkCode = String.Empty;



        System.Random random = new Random();



        for (int i = 0; i < 5; i++)

        {

            number = random.Next();

			code = (char)('0' + (char)(number % 10));

            //if (number % 2 == 0)

            //    code = (char)('0' + (char)(number % 10));

            //else

            //    code = (char)('A' + (char)(number % 26));



            checkCode += code.ToString();

        }



        Response.Cookies.Add(new HttpCookie("CheckCode", checkCode));



        return checkCode;

    }



    private void CreateCheckCodeImage(string checkCode)

    {

        if (checkCode == null || checkCode.Trim() == String.Empty)

            return;



        System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), 22);

        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);



            //画图片的背景噪音线

            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 System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));

            System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);

            g.DrawString(checkCode, font, brush, 2, 2);



            //画图片的前景噪音点

            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);



            System.IO.MemoryStream ms = new System.IO.MemoryStream();

            image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);

            Response.ClearContent();

            Response.ContentType = "image/Gif";

            Response.BinaryWrite(ms.ToArray());

        }

        finally

        {

            g.Dispose();

            image.Dispose();

        }

    }







}

mngzilin 2010-01-21

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用ajax干什么？
直接：
<img id="myimg" src="a.ashx" alt=""/>
<a onclick="test()">看不清楚换一张</a>

<script>
function test()
{
document.getElementById('myimg').src+="?";
}
</script>

江南小鱼 2010-01-21

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俺是这样用实现的



客户端使用.aspx(验证码页面)

<img id="img4" src="RandomJpgSample.aspx" onclick="javascript:this.src='RandomJpgSample.aspx?'+Math.random()" |"ShowNew()"/>



单击图片刷新验证码



<script type="Text/javascript">



    function ShowNew(){



     var img1=document.getElementById("img3");



     img1.src="RandomJpgSam.aspx?"+Math.random();



    }



    </script>