(转载)验证的代码
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;
using System.Drawing.Imaging;
public partial class Validata : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Session["code"] = RandNum(4);
ValidateCode(Session["code"].ToString(), 40, 20, "黑体", 10, "#FFFFFF");
}
/// <summary>
/// 该方法用于生成指定位数的随机数
/// </summary>
/// <param name="VcodeNum">参数是随机数的位数</param>
/// <returns>返回一个随机数字符串</returns>
private string RandNum(int VcodeNum)
{
string Vchar = "0,1,2,3,4,5,6,7,8,9";
string[] VcArray = Vchar.Split(',');//拆分成数组
string VNum = "";
int temp = -1;//记录上次随机数值,尽量避避免生产几个一样的随机数
Random rand = new Random();
//采用一个简单的算法以保证生成随机数的不同
for (int i = 0; i < VcodeNum; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));
}
int t = rand.Next(VcArray.Length - 1);
if (temp != -1 && temp == t)
{
return RandNum(VcodeNum);
}
temp = t;
VNum += VcArray[t];
}
return VNum;
}
/// <summary>
/// 生成图片并写入字符
/// </summary>
/// <param name="VNum">目标字符</param>
/// <param name="w">宽</param>
/// <param name="h">高</param>
/// <param name="font">字体文件</param>
/// <param name="fontSize">字体大小</param>
/// <param name="bgColor">图片背景颜色</param>
private void ValidateCode(string VNum, int w, int h, string font, int fontSize, string bgColor)
{
Bitmap Img = new Bitmap(w, h);//生成图像的实例
Graphics g = Graphics.FromImage(Img);//从Img对象生成新的Graphics对象
g.Clear(ColorTranslator.FromHtml(bgColor));//背景颜色
Font f = new Font(font, fontSize);//生成Font类的实例
SolidBrush s = new SolidBrush(Color.Black);//生成笔刷类的实例
g.DrawString(VNum, f, s, 3, 3);//将VNum写入图片中
Img.Save(Response.OutputStream, ImageFormat.Jpeg);//将此图像以Jpeg图像文件的格式保存到流中
Response.ContentType = "image/Jpeg";
//回收资源
g.Dispose();
Img.Dispose();
Response.End();
}
}
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上面的是产生验证码的 命名为 xxx.aspx.cs
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然后在登陆页面 [ login.aspx ] 中加一个Image控件 把地址指向它的前台就行。。
如下:
验证码:<asp:TextBox ID="Chkcode" runat="server" Columns="4" MaxLength="4"/>
<img src="Validata.aspx">
下一步,在login.aspx.cs 的确定按扭里加下面代码 用于比较:
if ( Chkcode.Text == Session["Code"].ToString() )
{
Session["Admin"] = "Admin";
Response.Write("<script>alert('登陆成功!');
}