Java中Date、LocalDate、LocalDateTime、LocalTime、时间戳之间的相互转换代码

    @Test
    public void test06(){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        // Date
        Date date = new Date();
        System.out.println("Date\t" + sdf.format(date));

        // Date 转 LocalDateTime
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        LocalDateTime dateToLocalDateTime = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDateTime();
        System.out.println("Date To LocalDateTime\t" + dtf.format(dateToLocalDateTime));
    }

    @Test
    public void test07(){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        // Date
        Date date = new Date();
        System.out.println("Date\t" + sdf.format(date));

        // Date 转 LocalDate
        // 注意 LocalDate 只能有年月日，格式化日期不能有时分秒，否则会报错
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        LocalDate dateToLocalDate = date.toInstant().atZone(ZoneId.systemDefault()).toLocalDate();
        System.out.println("Date To LocalDate\t" + dtf.format(dateToLocalDate));
    }

    @Test
    public void test08(){
        // LocalDateTime 转 LocalDate
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd");
        LocalDate localDateTimeToLocalDate = LocalDateTime.now().toLocalDate();
        System.out.println("LocalDateTime To LocalDate\t" + dtf.format(localDateTimeToLocalDate));
    }

    @Test
    public void test09(){
        // LocalDateTime 转 LocalTime
        // 注意 LocalTime 只能有时分秒，格式化日期不能有年月日，否则会报错
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("HH:mm:ss");
        LocalTime localDateTimeToLocalTime = LocalDateTime.now().toLocalTime();
        System.out.println("LocalDateTime To LocalTime\t" + dtf.format(localDateTimeToLocalTime));
    }

    @Test
    public void test10(){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        // LocalDateTime 转 Date
        ZoneId zoneId = ZoneId.systemDefault();
        Date localDateTimeToDate = Date.from(LocalDateTime.now().atZone(zoneId).toInstant());
        System.out.println("LocalDateTime To Date\t" + sdf.format(localDateTimeToDate));
    }

    @Test
    public void test11(){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        // LocalDate 转 Date
        Date LocalDateToDate = Date.from(LocalDate.now().atStartOfDay(ZoneId.systemDefault()).toInstant());
        System.out.println("LocalDate To Date\t" + sdf.format(LocalDateToDate));
    }

    @Test
    public void test12(){
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        // 时间戳 转 LocalDateTime
        Long timestamp = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli();
        LocalDateTime time2 = LocalDateTime.ofEpochSecond(timestamp/1000,0,ZoneOffset.ofHours(8));
        System.out.println("时间戳 To LocalDateTime\t" + dtf.format(time2));
    }