获取login控件里的textbox值的方法：
TextBox txtImage = Login2.FindControl("txtValidator") as TextBox;
if (txtImage.Text.ToString() == Request.Cookies["validate"].Value.ToString())
{
}
产生文件validate.aspx和validate.aspx.cs。
其中validate.aspx什么都没有，主要代码在validate.aspx.cs里：
protected void Page_Load(object sender, EventArgs e)
{
//在page_load事件中调用Generate()和CreateCheckCodeImage()函数
string str = GenerateCheckCode();
CreateCheckCodeImage(str);
}
private string GenerateCheckCode()
{
//利用random()随机产生四位大写的字符串（包含数字和字母）
int number;
char code;
string checkCode = string.Empty;
Random random = new Random();
for (int i = 0; i < 4; i++)
{
number = random.Next();
//下面也可以用其他的方法构思
if (number % 2 == 0)
code = (char)('0' + (char)(number % 10));
else
code = (char)('A' + (char)(number % 26));
checkCode += code.ToString();
}
//用cookies保存刚刚产生的随机字符串
Response.Cookies["validate"].Value = checkCode;
return checkCode;
}
private void CreateCheckCodeImage(string checkCode)
{
//该函数主要是画背景色的
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();
//清空背景色
g.Clear(Color.White);
//画背景的噪音线
for (int i = 0; i < 2; 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.Black), x1, y1, x2, y2);
}
Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold));
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(60, 60, 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();
}
}
然后在需要使用验证码的页面加上
<asp:TextBox ID="txtValidator" runat="server" Width="70px" Height="18px">
<asp:Image ID="Image1" runat="server" src="../inc/validate.aspx" />，注意路径是活的。
在cs文件里判断用户输入的验证码是不是正确的：
if(this.txtValidator.Text.ToString()==Request.Cookies["validate"].Value.ToString())
{
........//验证码通过，跳转
}
