一个验证码的例子（asp.net c#）

来源：互联网发布：原生linux 编辑：程序博客网时间：2024/05/17 02:15

主页面代码：

protected void Page_Load(object sender, EventArgs e)
    {
        string str=string.Empty;
        string str1 = "";
        System.Random random = new Random();
        int number;
        string checkCode="";
        char code;
        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();
}

    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        if (Request.Cookies["CheckCode"] == null)//判断Cookies变量
        {
            lblMessage.Text = "您的浏览器设置已被禁用 Cookies，您必须设置浏览器允许使用 Cookies 选项后才能使用本系统。";
            lblMessage.Visible = true;
            return;
        }

        if (String.Compare(Request.Cookies["CheckCode"].Value, txtCheckCode.Text, true) != 0)
        {
            lblMessage.Text = "验证码错误，请输入正确的验证码。";
            lblMessage.Visible = true;
            return;
        }
        else
        {
            Response.Redirect("KillApplication.aspx");
        }

}

验证码实现页面

protected void Page_Load(object sender, EventArgs e)
    {
        this.CreateCheckCodeImage(GenerateCheckCode());
    }
    private string GenerateCheckCode()
{
   int number;
   char code;
   string checkCode = String.Empty;//相当于checkCode="";

System.Random random = new Random();

   for(int i=0; i<5; i++)
   {
    number = random.Next();//返回随机非负数

    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));//添加Cookies变量

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();
   }
}