Generate the servlet of the Verification Code image on the user login page

 

Code

 /*
* To change this template, choose tools | templates
* And open the template in the editor.
*/

Package com. Qixin. Web;

Import java. AWT. Font;
Import java. AWT. graphics;
Import java. AWT. image. bufferedimage;
Import java. Io. ioexception;
Import java. Io. outputstream;
Import java. util. Random;
Import javax. ImageIO. ImageIO;
Import javax. servlet. servletexception;
Import javax. servlet. http. httpservlet;
Import javax. servlet. http. httpservletrequest;
Import javax. servlet. http. httpservletresponse;

/**
*
* @ Author Qixin
*/
Public class imageexample extends httpservlet {
// Used to generate a random number
Private random rand;
// Font used to display numbers
Private Font font;
// Width and height of the image
Private int width;
Private int height;

/**
* The input parameter is the output stream. This method generates an image and writes the data to the output stream.
* @ Param out
* @ Throws ioexception
*/
Private void outputimage (outputstream out) throws ioexception {
// Generate a random number of 1000-9999 and convert it into a string
String STR = integer. tostring (1000 + Rand. nextint (9000 ));
// Create a specified width and height image in the memory
Bufferedimage Bi = new bufferedimage (width, height, bufferedimage. type_int_rgb );
// Enter 20 white pixels at random
For (INT I = 0; I <20; I ++ ){
Int x = Rand. nextint (width );
Int y = Rand. nextint (height );
Bi. setrgb (X, Y, 0 xffffff );
}
// Obtain the object used to draw a character image
Graphics G = Bi. getgraphics ();
G. setfont (font );
// Draw characters. Note that the last two Parameters specify the coordinates in the lower left corner of the first character.
G. drawstring (STR, 0, height-1 );
// Resources are released immediately after graphics is used up to avoid waiting for garbage collection. Reduces resource usage
G. Dispose ();
// Send the image data to the output stream in JPG format. This method may throw an ioexception.
ImageIO. Write (Bi, "jpg", out );
}

@ Override
Public void Init (){
Rand = new random (system. currenttimemillis ());
Font = new font ("Courier New", Font. italic, 20 );
Width = 50;
Height = 20;
}
/**
* Processes requests for both HTTP <code> Get </code> and <code> post </code> methods.
* @ Param request Servlet Request
* @ Param response servlet response
* @ Throws servletexception if a servlet-specific error occurs
* @ Throws ioexception if an I/O error occurs
*/
Protected void processrequest (httpservletrequest request, httpservletresponse response)
Throws servletexception, ioexception {
// Set the MIME type to JPEG Image
Response. setcontenttype ("image/JPEG ");
// Obtain the binary output stream and pass it to the method for generating the image to return data
Outputimage (response. getoutputstream ());
}

// <Editor-fold defaultstate = "Collapsed" DESC = "httpservlet methods. Click on the + sign on the left to edit the code.">
/**
* Handles the HTTP <code> Get </code> method.
* @ Param request Servlet Request
* @ Param response servlet response
* @ Throws servletexception if a servlet-specific error occurs
* @ Throws ioexception if an I/O error occurs
*/
@ Override
Protected void doget (httpservletrequest request, httpservletresponse response)
Throws servletexception, ioexception {
Processrequest (request, response );
}

/**
* Handles the HTTP <code> post </code> method.
* @ Param request Servlet Request
* @ Param response servlet response
* @ Throws servletexception if a servlet-specific error occurs
* @ Throws ioexception if an I/O error occurs
*/
@ Override
Protected void dopost (httpservletrequest request, httpservletresponse response)
Throws servletexception, ioexception {
Processrequest (request, response );
}

/**
* Returns a short description of the servlet.
* @ Return a string containing servlet description
*/
@ Override
Public String getservletinfo (){
Return "Short Description ";
} // </Editor-fold>

}