[Add to favorites] generate verification Images

Generate verification Image

1. Image Generation class

Public class encryptimage {

Public String srand = "";

Public color getrandcolor (int fc, int BC) {// obtain a random color from a given range
Random random = new random ();
If (FC> 255)
Fc = 255;
If (BC> 255)
BC = 255;
Int r = FC + random. nextint (BC-Fc );
Int G = FC + random. nextint (BC-Fc );
Int B = FC + random. nextint (BC-Fc );
Return new color (R, G, B );
}

Public bufferedimage creatimage (){

// Create an image in memory
Int width = 60, Height = 20;
Bufferedimage image = new bufferedimage (width, height,
Bufferedimage. type_int_rgb );

// Obtain the image Context
Graphics G = image. getgraphics ();

// Generate a random class
Random random = new random ();

// Set the background color
G. setcolor (getrandcolor (200,250 ));
G. fillrect (0, 0, width, height );

// Set the font
G. setfont (new font ("Times New Roman", Font. Plain, 18 ));

// Draw a border
// G. setcolor (new color ());
// G. drawrect (0, 0, width-1, height-1 );
// Generates 155 random interference lines, making the authentication code in the image hard to be detected by other programs.
G. setcolor (getrandcolor (160,200 ));
For (INT I = 0; I <155; I ++ ){
Int x = random. nextint (width );
Int y = random. nextint (height );
Int XL = random. nextint (12 );
Int yl = random. nextint (12 );
G. drawline (X, Y, x + XL, Y + yl );
}

// Obtain the random ID code (4 digits)
// String Rand = request. getparameter ("RAND ");
// Rand = Rand. substring (0, Rand. indexof ("."));

For (INT I = 0; I <4; I ++ ){
String Rand = string. valueof (random. nextint (10 ));
Srand + = rand;
// Display the authentication code to the image
// The Color of the called function is the same. It may be because the seed is too close and can only be directly generated.
G. setcolor (new color (20 + random. nextint (110), 20 + random
. Nextint (110), 20 + random. nextint (110 )));
G. drawstring (RAND, 13 * I + 6, 16 );
}
// The image takes effect
G. Dispose ();
Return image;
}
/**
* @ Return returns the srand.
*/
Public String getsrand (){
Return srand;
}
/**
* @ Param Rand the srand to set.
*/
Public void setsrand (string rand ){
Srand = rand;
}
}

2 servlet output

Public class eimage extends httpservlet {

Public void doget (httpservletrequest request, httpservletresponse response)
Throws servletexception, ioexception {
Response. addheader ("Content-Type", "image/JPEG ");
Response. setheader ("Pragma", "No-Cache ");
Response. setheader ("cache-control", "No-Cache ");
Response. setdateheader ("expires", 0 );
Encryptimage Ei = new encryptimage ();
Bufferedimage IMG = ei. creatimage ();
Request. getsession (true). setattribute ("ecode", ei. getsrand ());
ImageIO. Write (IMG, "Jpeg", response. getoutputstream ());
}
}

3. check through the ecode IN THE SESSION