Calendar

Calendar calendar = Calendar.getInstance()
String year = calendar.get(Calendar.YEAR)          // 当前年份
String month = calendar.get(Calendar.MONTH)        // 当前月份
String day0 = calendar.get(Calendar.DAY_OF_YEAR)   // 今年的第几天
String day1 = calendar.get(Calendar.DAY_OF_MONTH)  // 当前月的第几天