4位数数字验证码源程序
BufferedImage bi = new BufferedImage(width,height,BufferedImage.TYPE_INT_BGR);
Graphics2D image = bi.createGraphics();
image.setColor(Color.orange);
image.fillRect(0,0,width,height);
image.setColor(Color.red);
image.drawRect(0,0,width-1,height-1);
Random rand= new Random();
String str ="";
