验证码的生成

1.验证码就是将大小写字母和数字放入到集合中，使用Collections.shuffle(list);将list集合中的数据进行打乱，遍历集合，对集合中的字符进行sb.append()操作，最后对sb进行下表截取 String result = afterShuffle.substring(5, 9);

代码
public class GenerateWord {
    public static void main(String[] args) {
        timer2();
    }

    // 第二种方法：设定指定任务task在指定延迟delay后进行固定延迟peroid的执行  
    // schedule(TimerTask task, long delay, long period)  
    public static void timer2() {
        Timer timer = new Timer();
        timer.schedule(new TimerTask() {
            public void run() {
                String[] beforeShuffle = new String[] { "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","g","k" };
                List<String> list = Arrays.asList(beforeShuffle);
                Collections.shuffle(list);
                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < list.size(); i++) {
                    sb.append(list.get(i));
                }
                String afterShuffle = sb.toString();
                String result = afterShuffle.substring(5, 9);
                System.out.println("验证码" + result);
            }
        }, 1000, 1000);

    }
}