asp.net Chinese verification Code, free open Source code _ Practical Tips

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.Text;
Using System.Drawing;

public partial class CnCode:System.Web.UI.Page
{
protected void Page_Load (object sender, EventArgs e)
{
Get GB2312 Encoding page (table)
Encoding GB = encoding.getencoding ("gb2312");

Call function generates 4 random Chinese encoding
object[] bytes = Createregioncode (4);

Decoding Chinese characters according to the encoding byte array
String str1 = GB. GetString ((byte[]) Convert.changetype (Bytes[0], typeof (byte[)));
String str2 = GB. GetString ((byte[]) Convert.changetype (Bytes[1], typeof (byte[)));
String str3 = GB. GetString ((byte[]) Convert.changetype (bytes[2], typeof (byte[)));
String STR4 = GB. GetString ((byte[]) Convert.changetype (Bytes[3], typeof (byte[)));

Console for output
CreateImage (str1 + str2 + str3 + STR4);

}

/*
This function randomly creates a hexadecimal byte array with two elements in the range of encoding, each byte array represents a character, and the
A four-byte array is stored in an object array.
Parameters: Strlength, representing the number of characters to be produced
*/
public static object[] Createregioncode (int strlength)
{
Defines a string array that stores the constituent elements of the encoding
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 ();

Defines an object array to
Object[] Bytes=new object[strlength];

/**//* produces a hexadecimal byte array of two elements at a time, and puts it in a bject array
Each Chinese character is composed of four location codes.
Location Code 1th and location code 2nd bit as the first element of a byte array
Location Code 3rd and Location Code 4th digits as the second element of a byte array
*/
for (int i=0;i<strlength;i++)
{
Location Code 1th Place
int R1=rnd. Next (11,14);
String STR_R1=RBASE[R1]. Trim ();

Location Code 2nd place
Rnd=new Random (r1*unchecked (int) DateTime.Now.Ticks) +i)//Replace the seed of the random number generator to avoid duplicate values
int R2;
if (r1==13)
{
R2=rnd. Next (0,7);
}
Else
{
R2=rnd. Next (0,16);
}
String STR_R2=RBASE[R2]. Trim ();

Location Code 3rd place
Rnd=new Random (r2*unchecked (int) DateTime.Now.Ticks) +i);
int R3=rnd. Next (10,16);
String STR_R3=RBASE[R3]. Trim ();

Location Code 4th place
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 ();

Defines a random Chinese character location code generated by two byte variable storage
Byte Byte1=convert.tobyte (str_r1 + str_r2,16);
Byte Byte2=convert.tobyte (STR_R3 + str_r4,16);
Storing two byte variables in a byte array
Byte[] Str_r=new Byte[]{byte1,byte2};

Puts a byte array of the resulting Chinese character into an object array
bytes. SetValue (Str_r,i);

}

return bytes;

}


private void CreateImage (string checkcode)
{
int iwidth = (int) (CHECKCODE.LENGTH * 25);
System.Drawing.Bitmap image = New System.Drawing.Bitmap (iwidth, 20);
Graphics g = graphics.fromimage (image);
Font f = new System.Drawing.Font ("Arial", System.Drawing.FontStyle.Bold);
Brush B = new System.Drawing.SolidBrush (color.white);
G.fillrectangle (New System.Drawing.SolidBrush (Color.Blue), 0,0,image. Width, image. Height);
G.clear (Color.Blue);
g.DrawString (Checkcode, F, B, 3, 3);

Pen Blackpen = new Pen (color.black, 0);
Random rand = new Random ();
for (int i = 0; i < 4; i++)
{
int y = rand. Next (image. Height);
G.drawline (blackpen, 0, y, image. Width, y);
}

System.IO.MemoryStream ms = new System.IO.MemoryStream ();
Image. Save (MS, System.Drawing.Imaging.ImageFormat.Jpeg);
Response.clearcontent ();
Response.ContentType = "Image/png";
Response.BinaryWrite (Ms. ToArray ());
G.dispose ();
Image. Dispose ();
}

}

The article is reproduced from the ' Great Intelligence Blog ': http://www.csafe.cn/article.asp?id=1274