Calendar calendar = Calendar.getInstance();//日历对象
//输出的月份是上一个月
System.out.println(calendar.get(Calendar.MONTH));
//输出本月
System.out.println(calendar.get(Calendar.MONTH))+1;
System.out.println(calendar.get(calendar.YEAR));
System.out.println(calendar.get(calendar.DATE));
//当前详细信息:Tue Dec 26 21:11:29 CST 2017
System.out.println(calendar.getTime());