Then the verification code is implemented (according to Han xianlong's Code)

Protected void page_load (Object sender, eventargs E)
{
Encoding GB = encoding. getencoding ("gb2312 ");
 
// Call the function to generate four random numbers.
Object [] bytes = createregioncode (4 );
 

String str1 = bytes [0]. tostring ();
String str2 = bytes [1]. tostring ();
String str3 = bytes [2]. tostring ();
String str4 = bytes [3]. tostring ();
 
// Output Console

// Response. Write (str1 + str2 + str3 + str4 );
// Return;

String SRS = str1 + str2 + str3 + str4;
Bitmap srbmp = srbitmap (SRS );
System. Io. memorystream SRMs = new system. Io. memorystream ();
Srbmp. Save (SRMs, system. Drawing. imaging. imageformat. GIF );
Response. clearcontent ();
Response. contenttype = "image/GIF ";
Response. binarywrite (SRMs. toarray ());
Srbmp. Dispose ();

}

/// <Summary>
/// Return the bitmap object based on the specified parameter
/// Reference:
/// Using system. drawing;
/// Call example:
/// Eg1. Save it as an image file
/// Bitmap srbmp = srbitmap (SRS );
/// Srbmp. Save (directory. getcurrentdirectory () + "\ srs.gif", system. Drawing. imaging. imageformat. GIF );
/// Srbmp. Dispose ();
/// Eg2. The webpage is called as follows:
/// Bitmap srbmp = srbitmap (SRS );
/// System. Io. memorystream SRMs = new system. Io. memorystream ();
/// Srbmp. Save (SRMs, system. Drawing. imaging. imageformat. GIF );
/// Response. clearcontent ();
/// Response. contenttype = "image/GIF ";
/// Response. binarywrite (SRMs. toarray ());
/// Srbmp. Dispose ();
/// </Summary>
/// <Param name = "SRS"> </param>
/// <Returns> </returns>

Public static bitmap srbitmap (string SRs)
{
// Define the image Bending Angle
Int srseedangle = 40;
// Define the image
Bitmap srbmp = new Bitmap (SRS. length * 20, 30 );
// Draw
Graphics srgraph = graphics. fromimage (srbmp );
// Clear the image
Srgraph. Clear (color. aliceblue );
// Draw a border for the image
Srgraph. drawrectangle (new pen (color. Black, 0), 0, 0, srbmp. Width-1, srbmp. Height-1 );
// Define the instant count
Random srrandom = new random ();
// Define the paint brush
Pen srpen = new pen (color. lightblue, 0 );
// Draw Noise
For (INT I = 0; I <100; I ++)
{
Srgraph. drawrectangle (srpen, srrandom. Next (1, srbmp. Width-2), srrandom. Next (1, srbmp. Height-2), 1, 1 );
}
// Convert a string into a character array
Char [] srchars = SRS. tochararray ();
// Archive text
Stringformat srformat = new stringformat (stringformatflags. noclip );
// Set the vertical center of Text
Srformat. Alignment = stringalignment. Center;
// Set the text to center horizontally
Srformat. linealignment = stringalignment. Center;
// Define the font color
Color [] srcolors = {color. Black, color. Red, color. darkblue, color. Blue, color. Orange, color. Brown, color. darkcyan, color. Purple };
// Define the font
String [] srfonts = {"verdana", "Microsoft sans serif", "Comic Sans MS", "Arial", ""};
// Draw each character cyclically
For (INT I = 0, j = srchars. length; I <j; I ++)
{
// Define the font parameters as the font style, font size, and font shape.

Font srfont = new font (srfonts [srrandom. Next (5)], 12, fontstyle. Regular );
// Fill the image
Brush srbrush = new solidbrush (srcolors [srrandom. Next (7)]);
// Define coordinates
Point srpoint = new point (16, 16 );
// Define the skew angle
Float srangle = srrandom. Next (-srseedangle, srseedangle );
// Skew
Srgraph. translatetransform (srpoint. X, srpoint. y );
Srgraph. rotatetransform (srangle );
// Fill in characters
Srgraph. drawstring (srchars [I]. tostring (), srfont, srbrush, 1, 1, srformat );
// Return to normal
Srgraph. rotatetransform (-srangle );
Srgraph. translatetransform (2,-srpoint. y );
}
Srgraph. Dispose ();
Return srbmp;
}

 

Public static object [] createregioncode (INT strlength)
{

 

String [] rbase = new string [10] {"0", "1", "2", "3", "4", "5", "6 ", "7", "8", "9 "};
Random RND = new random ();

// Define an object array

Object [] bytes = new object [strlength];

For (INT I = 0; I <strlength; I ++)
{
Int R1 = RND. Next (0, 10 );
String str_r1 = rbase [R1]. Trim ();
RND = new random (R1 * unchecked (INT) datetime. Now. ticks + I); // Replace the seed of the random number generator to avoid repeated values.

// Define the random digit location code generated by storing two byte Variables
Byte byte1 = convert. tobyte (str_r1, 16 );

// Put the byte array of the generated Chinese character into the object Array
Bytes. setvalue (byte1, I );

 

 

 

 

}

Return bytes;

}