public static Date calendarToData(int year, int month, int day) {
  Calendar calendar = Calendar.getInstance();//日历类的实例化
  calendar.set(year, month - 1, day);//设置日历时间，月份必须减一
  Date date = calendar.getTime(); // 从一个 Calendar 对象中获取 Date 对象
  return date;
 }
 System.out.println(calendarToData(2017,3,16));//打印测试

 public static Calendar dataToCalendar(Date date) {
  Calendar calendar = Calendar.getInstance();
  calendar.setTime(date);
  return calendar;
 }

 Date date = new Date();//直接new对象，获取的是当前时间
 System.out.println(dataToCalendar(date));//打印测试