ASP.NET教程:asp.net扩展Login控件,添加图文验证码
来源:学生作业帮助网 编辑:作业帮 时间:2024/05/10 23:14:33 ASP.NET
对asp提供的Login控件进行扩展,在密码后面加一图文验证功能以防止自动注册程序。
1.添加imageValidate.aspx,在头部添加信息
% Response.Buffer = true ;%
% Response.ExpiresAbsolute = DateTime.Now.AddSeconds(-1);%
% Response.Expires = 0 ;%
% Response.CacheControl = no-cache ; %
在imageValidate.aspx.cs中的代码
protected void Page_Load(object sender, EventArgs e)
{
//生成4位的验证码
/*string tmp = RndNum(4);
HttpCookie cookie = new HttpCookie(ImageV tmp);
//Response.Cookies[ImageV].Value=tmp;
Response.Cookies.Add(cookie);
this.ValidateCode(tmp);*/
CreateCheckCodeImage(GenerateCheckCode());
}
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();
if (number % 2 == 0)
code = (char)(‘0‘ + (char)(number % 10));
else
code = (char)(‘A‘ + (char)(number % 26));
checkCode += code.ToString();
}
Session[CheckCode] = checkCode;
//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();
}
}
这就是生成验证码的页面
2.将这页面添加到login控件中:
拖曳一Login控件,将之切换到模式下,在Html源文件中在表格中密码那行后添加:
tr
td style=width: 151px
asp:Label ID=Label1 runat=server AssociatedControlID=Password验证码:/asp:Label
/td
/tr
tr
td style=width: 151px
asp:TextBox ID=txtImgValid runat=server Font-Size=0.8em /asp:TextBox
asp:ImageButton id=imgValid ImageUrl=~/public/imageValidate.aspx runat=server /
/td
/tr
其中ImageUrl=~/public/imageValidate.aspx“ 的imageValidate.aspx指的就是我们第一步建立的文件。
3.在login控件的authenticate事件中加入代码
protected void Login1_Authenticate(object sender, AuthenticateEventArgs e)
{
TextBox txtImage = Login1.FindControl(txtImgValid) as TextBox;
if (Session[CheckCode] == null)
{
Response.Write(script language=‘javascript‘alert(‘未可知错误!‘)/script);
e.Authenticated = false;
return;
}
if (String.Compare(Session[CheckCode] .ToString(),txtImage.Text,true)!=0)
{
Response.Write(script language=‘javascript‘alert(‘不匹配!‘)/script);
e.Authenticated = false;
return;
}
e.Authenticated = true;
}
单击登录按钮后顺便将session清空
protected void LoginButton_Click(object sender, EventArgs e)
{
Session[CheckCode] = null;
}
运行结果如
ASP.NET