Java8常用日期格式化&字符串日期相互转换

 LocalDateTime localDateTime=LocalDateTime.now();
    //格式化日期时间类型为字符串
    DateTimeFormatter dateTimeFormatter=DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    String ss = dateTimeFormatter.format(localDateTime).toString();
    System.out.println(ss);
    //日期时间字符串类型转 LocalDateTime
    DateTimeFormatter df = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
    LocalDateTime yy = LocalDateTime.parse("2017-09-28 21:22:33", df);
    System.out.println(yy);
    //日期字符串转日期类型
    LocalDate localDate=LocalDate.parse("2019-12-10",DateTimeFormatter.ofPattern("yyyy-MM-dd"));
    System.out.println(localDate.toString());
}