String DATE_FORMAT = "yyyy-MM-dd";
LocalDate localDate = LocalDate.now();
long startTime = localDate.atTime(0, 0, 0).toEpochSecond(ZoneOffset.of("+8"));
long endTime = localDate.plusDays(1).atTime(0, 0, 0).toEpochSecond(ZoneOffset.of("+8")) - 1;
String result = localDate.format(DateTimeFormatter.ofPattern(DATE_FORMAT));
System.out.println(result);
System.out.println(startTime);
System.out.println(endTime);
System.out.println("*******************");
Date date = new Date();
SimpleDateFormat df = new SimpleDateFormat(DATE_FORMAT);
String time = df.format(date);
System.out.println(df.parse(time).getTime());
运行结果：
2019-02-13 1549987200 1550073599 ******************* 1549987200000