日期操作

1、获取当天 00:00:00 

// 获取当天00:00:00
Calendar begin = Calendar.getInstance();
begin.set(begin.get(Calendar.YEAR), begin.get(Calendar.MONTH), begin.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
// 设置毫秒为0
begin.set(Calendar.MILLISECOND, 0);
Date date = begin.getTime();

2、字符串格式转日期

// 时间格式
DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
// 解析时间
LocalDateTime dateTime = LocalDateTime.parse("2020-11-20 15:30:30", df);
// date
Date date = Date.from(dateTime.atZone(ZoneId.systemDefault()).toInstant());

DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd");
// 解析日期
LocalDate dataDate = LocalDate.parse("2020-11-20", df);
Date date1 = Date.from(dataDate.atStartOfDay().atZone(ZoneId.systemDefault()).toInstant());

3、日期转字符串

// 格式化时间
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String dateStr = LocalDateTime.now().format(formatter);