转载：https://blog.csdn.net/iamzhangyouzhi/article/details/38542401
方法一：
Date date = new Date();
int hours = date.getHours();
方法二：
GregorianCalendar calendar = new GregorianCalendar();
int hour = calendar.get(Calendar.HOUR_OF_DAY);
System.out.println("hour=" + hour);