1.获取月份的第一天和最后一天

DateTimeFormatter dailyFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");

//获取相应的月份，也可用YearMonth.of(2019,7)指定月份
YearMonth month = YearMonth.now().minusMonths(1);
String start = month.atDay(1).format(dailyFormatter);
String end = month.atEndOfMonth().format(dailyFormatter);

2.获取一年的第一天和最后一天

Year year = Year.now().minusYears(1);
String start = year.atDay(1).format(dailyFormatter);
String end = year.atMonth(12).atEndOfMonth().format(dailyFormatter);