1、第一步生成背景板
public void generateCheckCode(HttpServletRequest request, HttpServletResponse response) throws IOException { //服务器通知浏览器不要缓存 response.setHeader("pragma", "no-cache"); response.setHeader("cache-control", "no-cache"); response.setHeader("expires", "0"); //在内存中创建一个长80,宽30的图片,默认黑色背景 //参数一:长 //参数二:宽 //参数三:颜色 int width = 80; int height = 30; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); //获取画笔 Graphics g = image.getGraphics(); //设置画笔颜色为灰色 g.setColor(Color.BLACK); //填充图片 g.fillRect(0, 0, width, height); //产生4个随机验证码,12Ey String checkCode = getCheckCode(); //将验证码放入HttpSession中 request.getSession().setAttribute("checkCode", checkCode); //设置画笔颜色为黄色 g.setColor(Color.WHITE); //设置字体的小大 g.setFont(new Font("黑体", Font.BOLD, 24)); //向图片上写入验证码 g.drawString(checkCode, 15, 25); //将内存中的图片输出到浏览器 //参数一:图片对象 //参数二:图片的格式,如PNG,JPG,GIF //参数三:图片输出到哪里去 ImageIO.write(image, "PNG", response.getOutputStream()); }
2、第二步生成验证码字符串
private String getCheckCode() {
String base = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
int size = base.length();
Random r = new Random();
StringBuilder sb = new StringBuilder();
for (int i = 1; i <= 4; i++) {
//产生0到size-1的随机值
int index = r.nextInt(size);
//在base字符串中获取下标为index的字符
char c = base.charAt(index);
//将c放入到StringBuffer中去
sb.append(c);
}
return sb.toString();
}
标签:Java,checkCode,int,验证码,生成,base,new,response From: https://www.cnblogs.com/gdwm-tyf/p/17362136.html