JSP generated verification code picture

<% @ Page ContentType = "Image / JPEG" Import = "java.awt. *,

Java.awt.Image. *, java.util. *, javax.imageio. * "%>

<%!

Color GetrandColor (int FC, int BC) {// Get random colors

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);

}

%>

<%

/ / Set the page does not cache

Response.setHeader ("Pragma", "NO-Cache");

Response.setHeader ("cache-control", "no-cache");

Response.SetDateHeader ("Expires", 0);

/ / Create image in memory

INT width = 60, height = 20;

BufferedImage Image = New BufferedImage (width, height, bufferedimage.type_int_rgb);

/ / Get the graphical 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));

// Sea Box

//g.setcolor (New Color ());

//g.drawrect (0, 10 ,width-1, Height 1);

// randomly generate 155 interferent lines, so that the authentication code in the image is not easily 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);

}

// Take the randomly generated authentication code (4 digits)

String SRAND = "";

For (int i = 0; i <4; i ) {

String Rand = String.Valueof (random.nextint (10));

SRAND = Rand;

// Display the authentication code to the image

G.SetColor (New Color (20 Random.Nextint (110), 20 Random.Nextint (110), 20 Random.Nextint (110))));

// The color of the call function is the same, it may be because the seed is too close, so it can only be generated directly.

g.drawstring (rand, 13 * i 6, 16);

// Deposit the authentication code into the session

Session.setttribute ("Rand", SRAND);

// Image take effect

g.dispose ();

// Output image to page

Imageio.write (Image, "JPEG", response.getOutputStream ());

%>

File A.jsp using the verification code picture

<% @ Page ContentType = "text / html; charset = GB2312"%>