ASP.NET 验证码 不同浏览器 不刷新问题

具体为什么不刷新是缓存机制不同，验证码图片的src或ImageUrl的获取是来自一个文件，由于连接地址没变所以不同内核浏览器有的会认为源没有变，解决办法就是在连接后面加上一个随机参数如可以用JS的Math.radom()

我在网上找的一个是凡的世界

http://www.cnblogs.com/Impulse/archive/2008/06/19/1226123.html

image.aspx.cs文件内容

using System;

using System.Data;

using System.Configuration;

using System.Collections;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Drawing.Design;

using System.Drawing;

public partial class imagecode : System.Web.UI.Page

{

Random r = new Random();//声名产生随机数的变量

protected void Page_Load(object sender, EventArgs e)

{

this.CreateCheckCodeImage(RndNum());

}

private string RndNum()

{

int number;

char code;

string checkCode = String.Empty;

System.Random random = new Random();

for (int i = 0; i < 4; i++)

{

number = random.Next();

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("yzmcode", 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();

}

}

}

//验证码使用页login.aspx中的代码

<asp:ImageButton ID="yzm" runat="server" ImageUrl="imagecode.aspx" />

< asp:LinkButton ID="ChangeCode" runat="server" Text="看不清楚？换一个验证码" OnClick="ChangeCode_Click" />

< asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button" /></div>

//ogin.aspx.cs中的代码

添加

//啥代码也不用写 点击“看不清楚？换一个验证码”以后就可以刷新验证码

protected void ChangeCode_Click(object sender, EventArgs e)

{

   this.ImageButton1.ImageUrl = "imagecode.aspx?id=" + r.Next();//这里是我加上的，可以解决有些浏览器不刷新问题

}

//提交按钮代码这里是通过cookies来验证的

protected void Button1_Click(object sender, EventArgs e)

{

if (String.Compare(Request.Cookies["yzmcode"].Value, a.Text, true) != 0)

{

Response.Write("<script>alert('验证码错误!')</script>");

}

else

{ Response.Write("<script>alert('验证吗正确!!!')</script>"); }

}