日期转换工具类

简单说明
基于jdk1.8版本编写、测试；使用jdk1.8新日期、时间API；
支持情况
LocalDateTime -> String 与 String -> LocalDateTime 的互转String -> Long 与 Long -> String 的互转LocalDateTime -> Long 与 Long -> LocalDateTime 的互转基于LocalDateTime的日期类型比较（isAfter/isBefore/isEqual）
具体代码

import java.time.*;
import java.time.format.DateTimeFormatter;


public class DateTimeUtil {
    public static String DATE_TIME_EN = "yyyy-MM-dd HH:mm:ss";
    public static String DATE_TIME_ZH = "yyyy年MM月dd日 HH时mm分ss秒";
    public static String DATE_EN = "yyyy-MM-dd";
    public static String DATE_ZH = "yyyy年MM月dd日";
    public static String TIME_EN = "HH:mm:ss";
    public static String TIME_ZH = "HH时mm分ss秒";
    public static DateTimeFormatter defaultFormatter;

    static {
        defaultFormatter = DateTimeFormatter.ofPattern(DATE_TIME_EN);
    }

    
    public static String format(LocalDateTime date, String pattern) {
        return  DateTimeFormatter.ofPattern(pattern).format(date);
    }

    
    public static String format(LocalDateTime date) {
        return defaultFormatter.format(date);
    }

    
    public static LocalDateTime parse(String date, String pattern) {
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern(pattern);
        return LocalDateTime.parse(date, dtf);
    }

    
    public static LocalDateTime parse(String date) {
        return LocalDateTime.parse(date, defaultFormatter);
    }

    
    public static Long parseSecond(String date, String pattern) {
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern(pattern);
        return getSecond(LocalDateTime.parse(date, dtf));
    }

    
    public static Long parseSecond(String date) {
        return getSecond(LocalDateTime.parse(date, defaultFormatter));
    }

    
    public static Long parseMilli(String date, String pattern) {
        DateTimeFormatter dtf = DateTimeFormatter.ofPattern(pattern);
        return getMilli(LocalDateTime.parse(date, dtf));
    }

    
    public static Long parseMilli(String date) {
        return getMilli(LocalDateTime.parse(date, defaultFormatter));
    }

    
    public static Long getSecond(LocalDateTime date) {
        return date.toInstant(OffsetDateTime.now().getOffset()).getEpochSecond();
    }

    
    public static Long getMilli(LocalDateTime date) {
        return date.toInstant(OffsetDateTime.now().getOffset()).toEpochMilli();
    }

    
    public static LocalDateTime getLocalDateTime(Long date) {
        // 获取date的位数
        int i = Long.toString(date).length();
        if (i == 13) {
            return LocalDateTime.ofInstant(Instant.ofEpochMilli(date), ZoneId.systemDefault());
        } else if (i == 10) {
            return LocalDateTime.ofInstant(Instant.ofEpochSecond(date), ZoneId.systemDefault());
        } else {
            throw new DateTimeException("不支持");
        }
    }

    
    public static String getDateString(Long date, String pattern) {
        LocalDateTime localDateTime = getLocalDateTime(date);
        return localDateTime.format(DateTimeFormatter.ofPattern(pattern));
    }

    
    public static String getDateString(Long date) {
        return getLocalDateTime(date).format(defaultFormatter);
    }

    public static boolean isAfter(LocalDateTime date, LocalDateTime other) {
        return date.isAfter(other);
    }

    public static boolean isBefore(LocalDateTime date, LocalDateTime other) {
        return date.isBefore(other);
    }

    public static boolean isEqual(LocalDateTime date, LocalDateTime other) {
        return date.isEqual(other);
    }

}