Use java to randomly generate a four-digit verification code and find the programming code.

I made it myself and used it as a JSP for verification code in the system.

& lt% @ page contenttype = "image/JPEG; charset = utf-8 " % & gt；

& lt%@page import="java.util.*，java.awt.*，java.awt.image.*，javax.imageio. * " % & gt

& lt% @ page import = " Java . io . output stream " % & gt；

& lthtml & gt

& ltbody & gt

& lt%!

Color getRandColor(int fc，int bc)

{

Random rd = new Random()；

if(fc & gt； 255)fc = 255；

if(BC & gt； 255)BC = 255；

int red = fc+rd . nextint(BC-fc)；

int green = fc+rd . nextint(BC-fc)；

int blue = fc+rd . nextint(BC-fc)；

Returns a new color (red, green, blue);

}

% & gt

& lt%

Random r = new Random()；

Response.addHeader("Pragma ","no cache ");

response . add header(" Cache-Control "，" no-Cache ")；

response . adddate header(" expires "，0)；

int width = 90

int height = 23

Buffered image pic = new buffered image (width, height, buffered image. TYPE _ INT _ RGB)；

graphics GC = pic . get graphics()；

gc.setColor(getRandColor(200，250))；

gc.fillRect(0，0，width，height)；

String[] rNum ={"0 "，" 1 "，" 2 "，" 3 "，" 4 "，" 5 "，" 6 "，" 7 "，" 8 "，" 9 "，" a "，" b "，" c "，" d "，" e "，" f "，

" g "，" h "，" I "，" j "，" k "，" l "，" m "，" n "，" o "，" p "，" q "，" r "，" s "，" t "，" u "，" v "，" w "，

“x”，“y”，“z”，“A”，“B”，“C”，“D”，“E”，“F”，“G”，“H”，“I”，“J”，“K”，“L”，“M”，“N”，

“O”、“P”、“Q”、“R”、“S”、“T”、“U”、“V”、“W”、“X”、“Y”、“Z”}；

int[] style = {Font。 Ordinary font. Bold, font. Italic, font. Plain color+font. Bold,

Font. Bold+font. Italic, font. Plain color+font. Italic, font. Plain color+font. Bold+font. Italic};

Gc.setColor (color. White);

gc.drawLine(0，30，90， 10)；

GC . set color(getRandColor( 160，200))；

for(int I = 0； I & lt50; i++)

{

Int x = r.nextInt (width);

int y = r . nextint(height)；

int XL = r . nextint( 10)；

int yl = r . nextint( 10)；

gc.drawLine(x，y，x+xl，y+yl)；

}

gc.setColor(getRandColor(60， 150))；

String rt =

for(int I = 0； I<4; i++){

string temp = rNum[r . nextint(62)]；

rt = rt+temp；

GC . set Font(New Font(" Times New Roman "，style[r.nextInt(7)]， 15))；

gc.drawString(temp，5+I * 15+r . nextint( 10)， 10+r . nextint( 10))；

}

GC . dispose()；

session.setAttribute("randNum "，rt)；

output stream OS = response . get output stream()；

ImageIO.write(pic，“JPEG”，OS)；

System.out.println ("current verification code is:"+session.getattribute ("randnum"));

OS . flush()；

OS . close()；

os = null

response . flush buffer()；

out . clear()；

out = pagecontext . push body()；

% & gt

& lt/body & gt；

& lt/html & gt；