生成验证码

public class ValidataCode extends HttpServlet {
        
        private static final long serialVersionUID = -4144854995411893258L;

        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            getValidataCode(request,response);
        }
        
        private final int  WIDTH = 110;
        private final int  HEIGHT = 40;//ctrl+shift+x转化大写  ctrl+shift+y转化小写  
        
        private void getValidataCode(HttpServletRequest request,HttpServletResponse response){
            BufferedImage bufImg = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_RGB);
            Graphics2D graphics =bufImg.createGraphics();
            graphics.setColor(new Color(250,250,210));
            graphics.fillRect(0, 0, WIDTH, HEIGHT);
            graphics.setColor(new Color(233,150,122));
            graphics.setFont(new Font("Consolas",Font.BOLD,22));
            String validataStr = "1234567890qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM";
            Random random = new Random();
            String validataCode="";
            for(int i=0;i<4;i++){
                char c = validataStr.charAt(random.nextInt(validataStr.length()));
                validataCode += c;
                int width = (i+1)*20;
                int radian = random.nextInt(61) - 30;
                graphics.rotate(radian*Math.PI/180, width, 20);
                graphics.drawString(c+"", width, 20);
                graphics.rotate(-radian*Math.PI/180, width, 20);
                graphics.drawLine(width, random.nextInt(HEIGHT), random.nextInt(WIDTH), random.nextInt(HEIGHT));
                
            }
            
            graphics.drawLine(random.nextInt(WIDTH), random.nextInt(HEIGHT), random.nextInt(WIDTH), random.nextInt(HEIGHT));
            HttpSession session =request.getSession();//获取session
            session.setAttribute("VALIDATACODE", validataCode);//设置session值
            try {
                OutputStream out = response.getOutputStream();
                ImageIO.write(bufImg, "png", out);
                out.flush();
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            
        }
}