asp.net generates verification code (pure numbers)

CheckCode.cs

using System; 
using System.Data; 
using System.Configuration; 
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; 
/// <summary> 
/// CheckCode 的摘要说明 
/// </summary> 
public class CheckCode 
{ 
public CheckCode() 
{ 
// 
// TODO: 在此处添加构造函数逻辑 
// 
} 
public static void DrawImage() 
{ 
CheckCode img = new CheckCode(); 
HttpContext.Current.Session["CheckCode"] = img.RndNum(4); 
img.checkCodes(HttpContext.Current.Session["CheckCode"].ToString()); 
} 
/// <summary> 
/// 生成验证图片 
/// </summary> 
/// <param name="checkCode">验证字符</param> 
private void checkCodes(string checkCode) 
{ 
int iwidth = (int)(checkCode.Length * 13); 
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 23); 
Graphics g = Graphics.FromImage(image); 
g.Clear(Color.White); 
//定义颜色 
Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple }; 
//定义字体 
string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" }; 
Random rand = new Random(); 
//随机输出噪点 
for (int i = 0; i < 50; i++) 
{ 
int x = rand.Next(image.Width); 
int y = rand.Next(image.Height); 
g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1); 
} 
//输出不同字体和颜色的验证码字符 
for (int i = 0; i < checkCode.Length; i++) 
{ 
int cindex = rand.Next(7); 
int findex = rand.Next(5); 
Font f = new System.Drawing.Font(font[findex], 10, System.Drawing.FontStyle.Bold); 
Brush b = new System.Drawing.SolidBrush(c[cindex]); 
int ii = 4; 
if ((i + 1) % 2 == 0) 
{ 
ii = 2; 
} 
g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * 12), ii); 
} 
//画一个边框 
g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1); 
//输出到浏览器 
System.IO.MemoryStream ms = new System.IO.MemoryStream(); 
image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); 
HttpContext.Current.Response.ClearContent(); 
//Response.ClearContent(); 
HttpContext.Current.Response.ContentType = "image/Jpeg"; 
HttpContext.Current.Response.BinaryWrite(ms.ToArray()); 
g.Dispose(); 
image.Dispose(); 
} 
/// <summary> 
/// 生成随机的字母 
/// </summary> 
/// <param name="VcodeNum">生成字母的个数</param> 
/// <returns>string</returns> 
private string RndNum(int VcodeNum) 
{ 
string Vchar = "0,1,2,3,4,5,6,7,8,9"; 
string[] VcArray = Vchar.Split(&#39;,&#39;); 
string VNum = ""; //由于字符串很短，就不用StringBuilder了 
int temp = -1; //记录上次随机数值，尽量避免生产几个一样的随机数 
//采用一个简单的算法以保证生成随机数的不同 
Random rand = new Random(); 
for (int i = 1; i < VcodeNum + 1; i++) 
{ 
if (temp != -1) 
{ 
rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks)); 
} 
int t = rand.Next(VcArray.Length); 
if (temp != -1 && temp == t) 
{ 
return RndNum(VcodeNum); 
} 
temp = t; 
VNum += VcArray[t]; 
} 
return VNum; 
} 
}

Create another page checkCode.aspx that references the class. You don’t need to write anything in the front desk. You can just reference the DrawImage() method of the class we created in the background.

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; 
public partial class checkCode : System.Web.UI.Page 
{ 
protected void Page_Load(object sender, EventArgs e) 
{ 
CheckCode.DrawImage(); 
} 
}

Below we can reference the checkCode.aspx page on the page that requires a verification code.
Front Desk

<asp:TextBox ID="Validator" runat="server" Width="150px" ></asp:TextBox> 
<img id="Img1" alt="看不清，请点击我！" onclick="this.src=this.src+&#39;?&#39;" src="checkCode.aspx" 
style="width: 73px; height: 22px" align="left" /> 
<asp:ImageButton ID="imgBtnLogin" runat="server" ImageUrl="~/Images/Login.GIF" 
OnClick="imgBtnLogin_Click" />

Backend Judgment

protected void imgBtnLogin_Click(object sender, ImageClickEventArgs e) 
{ 
if(this.Validator.Text==Session["CheckCode"].ToString()) 
{ 
//。。。。 
} 
else 
{ 
Response.Write("<script>alert(&#39;验证码输入错误，请重新输入！&#39;);Location=&#39;MumberValidate.aspx&#39;</script>"); 
return; 
} 
}

Please modify the above code appropriately according to the actual situation.

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