3 types of verification code examples in asp.net (numbers, mixed numbers and letters, Chinese characters)

The effect is shown in the figure:

##Default.aspx

<table> 
<tr> 
<td class="style1"> 
 (验证码测试)</td> 
<td> 
  <asp:Label 
ID="Label1" runat="server"></asp:Label> 
  
<asp:Image ID="Image1" runat="server" Height="22px" ImageUrl="~/ValidNums.aspx" Width="58px" />  
<asp:Image ID="Image2" runat="server" Height="22px" ImageUrl="~/GetValid.aspx" Width="58px" /></td> 
</tr> <tr> 
<td class="style1"> 
  
</td> 
<td> 
  <asp:Button ID="Button1" runat="server" Text="登录" OnClick="btnOK_Click" /> 
   
<asp:Button ID="Button2" runat="server" Text="取消" /> 
</td> 
</tr> 
</table>

rrree

GetValid.aspx

( You can directly assign this page as a source to ImageUrl)
The front desk is empty, and the background code is as follows:

using System; 
using System.Collections.Generic; 
using System.Linq; 
using System.Web; 
using System.Web.UI; 
using System.Web.UI.WebControls; 

public partial class _Default : System.Web.UI.Page 
{ 
protected void Page_Load(object sender, EventArgs e) 
{ 
if (!Page.IsPostBack) 
{ 
string getNums = GetVali(); 
Label1.Text = getNums; 
} 
} 

/// <summary> 
/// 随机生成4位数 
/// </summary> 
/// <returns>返回生成的随机数</returns> 
public string GetVali() 
{ 
string strsvali = "0,1,2,3,4,5,6,7,8,9"; 
string[] ValiArray = strsvali.Split(&#39;,&#39;); 
string ReturnNum = ""; 
int nums = -1; 
Random vrand = new Random(); 
for (int n = 1; n < 5; n++) 
{ 
if (nums != -1) 
{ 
vrand = new Random(n * nums * unchecked((int)DateTime.Now.Ticks)); 
} 
int t = vrand.Next(10); 
nums = t; 
ReturnNum += ValiArray[t]; 
} 
Session["Valid"] = ReturnNum; 
return ReturnNum; 
} 
protected void btnOK_Click(object sender, EventArgs e) 
{ 
if (Session["Valid"].ToString() == TextBox3.Text) 
{ 
ClientScript.RegisterStartupScript(this.GetType(),"ss","<script>alert(&#39;您已经成功通过登录验证！&#39;)</script>"); 
} 
else 
{ 
ClientScript.RegisterStartupScript(this.GetType(), "ss", "<script>alert(&#39;您输入的验证码错误！&#39;)</script>"); 
} 
} 
}

ValidNums.aspx

(You can directly assign this page as a source to ImageUrl)
The front desk is empty, and the background code is as follows:

using System; 
using System.Collections; 
using System.Configuration; 
using System.Data; 
using System.Linq; 
using System.Web; 
using System.Web.Security; 
using System.Web.UI; 
using System.Web.UI.HtmlControls; 
using System.Web.UI.WebControls; 
using System.Web.UI.WebControls.WebParts; 
using System.Xml.Linq; 
using System.Text; 
using System.Drawing; 

public partial class GetValid : System.Web.UI.Page 
{ 
protected void Page_Load(object sender, EventArgs e) 
{ 
if (!IsPostBack) 
{ 
string validateNum = GetValids(); //成生4位随机字符串 
CreateImage(validateNum); //将生成的随机字符串绘成图片 
Session["ValidNums"] = validateNum; //保存验证码 
} 
} 
public static string GetValids() 
{ 
//获取GB2312编码页（表） 
Encoding gb = Encoding.GetEncoding("gb2312"); 

//调用函数产生4个随机中文汉字编码 
object[] bytes = CreateRegionCode(4); 

//根据汉字编码的字节数组解码出中文汉字 

string s = String.Empty; 
foreach (object byt in bytes) 
{ 
string str1 = gb.GetString((byte[])Convert.ChangeType(byt, typeof(byte[]))); 
s = s + str1; 
} 

//输出的控制台 
return s; 
} 
public static object[] CreateRegionCode(int strlength) 
{ 
//定义一个字符串数组储存汉字编码的组成元素 
string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" }; 

Random rnd = new Random(); 

//定义一个object数组用来 
object[] bytes = new object[strlength]; 
/*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中 
每个汉字有四个区位码组成 
区位码第1位和区位码第2位作为字节数组第一个元素 
区位码第3位和区位码第4位作为字节数组第二个元素 
*/ 
for (int i = 0; i < strlength; i++) 
{ 
//区位码第1位 
int r1 = rnd.Next(11, 14); 
string str_r1 = rBase[r1].Trim(); 

//区位码第2位 
rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i); 
//更换随机数发生器的种子避免产生重复值 
int r2; 
if (r1 == 13) 
{ 
r2 = rnd.Next(0, 8); 
} 
else 
{ 
r2 = rnd.Next(0, 16); 
} 
string str_r2 = rBase[r2].Trim(); 

//区位码第3位 
rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i); 
int r3 = rnd.Next(10, 16); 
string str_r3 = rBase[r3].Trim(); 

//区位码第4位 
rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i); 
int r4; 
if (r3 == 10) 
{ 
r4 = rnd.Next(1, 16); 
} 
else if (r3 == 15) 
{ 
r4 = rnd.Next(0, 15); 
} 
else 
{ 
r4 = rnd.Next(0, 16); 
} 
string str_r4 = rBase[r4].Trim(); 

//定义两个字节变量存储产生的随机汉字区位码 
byte byte1 = Convert.ToByte(str_r1 + str_r2, 16); 
byte byte2 = Convert.ToByte(str_r3 + str_r4, 16); 
//将两个字节变量存储在字节数组中 
byte[] str_r = new byte[] { byte1, byte2 }; 

//将产生的一个汉字的字节数组放入object数组中 
bytes.SetValue(str_r, i); 

} 

return bytes; 

} 
//生成图片 
private void CreateImage(string validateNum) 
{ 
if (validateNum == null || validateNum.Trim() == String.Empty) 
return; 
//生成Bitmap图像 
System.Drawing.Bitmap image = new System.Drawing.Bitmap(validateNum.Length * 12 + 10, 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.Coral), x1, y1, x2, y2); 
} 

Font font = new System.Drawing.Font("Arial", 8); 
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(validateNum, 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(); 
//将图像保存到指定的流 
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif); 
Response.ClearContent(); 
Response.ContentType = "image/Gif"; 
Response.BinaryWrite(ms.ToArray()); 
} 
finally 
{ 
g.Dispose(); 
image.Dispose(); 
} 
} 
}

The above are all codes for the three verification codes.

You can also use ashx to request the verification code. This example only uses Session value processing.

For more related articles on 3 types of verification code examples in asp.net (numbers, mixed numbers and letters, Chinese characters), please pay attention to the PHP Chinese website!