Java时间格式转换，涉及String，Date类型时间格式，时间戳之间互转

Java时间日期格式转换工具类（带注释）

 

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.format.DateTimeFormatter;
import java.util.Date;

public class DateUtils {

 private final static SimpleDateFormat shortSdf = new SimpleDateFormat("yyyy-MM-dd");
 private final static SimpleDateFormat monthSdf = new SimpleDateFormat("yyyy-MM");
 private final static SimpleDateFormat longSdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

    //获取String类型的时间格式
    public static String getYYYYMMDDHHMMSS() {
        Date d = new Date();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        return  sdf.format(d);
    }

    //String to Date时间类型转换
    public static Date StringToDate(String str){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date date=null;
        try {
            date=sdf.parse(str);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return  date;
    }

    //Date to String时间类型转换
    public static String DateString(Date date){
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        return   sdf.format(date);
    }

    //将String类型时间转换为时间戳
    public static String dateToStamp(String s){
        String res;
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        Date date = null;
        try {
            date = simpleDateFormat.parse(s);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        long ts = date.getTime();
        res = String.valueOf(ts);
        return res;
    }

    //将时间戳转换为String类型时间

    public static String stampToDate(String s){
        String res;
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        long lt = new Long(s);
        Date date = new Date(lt);
        res = simpleDateFormat.format(date);
        return res;
    }

    //获取距离当前时间前几天（月,年）或后几天的时间,n为负为前几天，正是后几天.plusMonth(n),plusYear(n)相同
    public static String getDayBefore(Integer n){

        return LocalDateTime.now().plusDays(n).format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
    }

    //获取一天的开始时间，2018,4,2 00:00
    public static LocalDateTime getDayStart(LocalDateTime time) {
        return time.withHour(0)
                .withMinute(0)
                .withSecond(0)
                .withNano(0);
    }

    //获取一天的结束时间，2018,4,2 23:59:59.999999999
    public static LocalDateTime getDayEnd(LocalDateTime time) {
        return time.withHour(23)
                .withMinute(59)
                .withSecond(59)
                .withNano(999999999);
    }

    //获得两个日期之间的所有天数
    public static List dateSplit(Date startDate, Date endDate)
            throws Exception {
        if (startDate.after(endDate))
            throw new Exception("开始时间应该在结束时间之后");
        Long spi = endDate.getTime() - startDate.getTime();
        Long step = spi / (24 * 60 * 60 * 1000);// 相隔天数

        List dateList = new ArrayList();
        dateList.add(endDate);
        for (int i = 1; i <= step; i++) {
            dateList.add(new Date(dateList.get(i - 1).getTime()
                    - (24 * 60 * 60 * 1000)));// 比上一天减一

        }
        return dateList;
    }

    //获得两个日期之间的所有月份
    public static List getMonthBetween(String minDate, String maxDate) throws 
    ParseException {
        ArrayList result = new ArrayList();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");//格式化为年月

        Calendar min = Calendar.getInstance();
        Calendar max = Calendar.getInstance();

        min.setTime(sdf.parse(minDate));
        min.set(min.get(Calendar.YEAR), min.get(Calendar.MONTH), 1);

        max.setTime(sdf.parse(maxDate));
        max.set(max.get(Calendar.YEAR), max.get(Calendar.MONTH), 2);

        Calendar curr = min;
        while (!(curr.after(max))) {
            result.add(sdf.format(curr.getTime()));
            curr.add(Calendar.MONTH, 1);
        }

        return result;
    }


   //获得本月的开始时间
    public static String getCurrentMonthStartTime() {
        Calendar c = Calendar.getInstance();
        Date now = null;
        try {
            c.set(Calendar.DATE, 1);
            now = shortSdf.parse(shortSdf.format(c.getTime()));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return longSdf.format(now);
    }

    //获得本月的结束时间
    public static String getCurrentMonthEndTime() {
        Calendar c = Calendar.getInstance();
        Date now = null;
        try {
            c.set(Calendar.DATE, 1);
            c.add(Calendar.MONTH, 1);
            c.add(Calendar.DATE, -1);
            now = longSdf.parse(shortSdf.format(c.getTime()) + " 23:59:59");
        } catch (Exception e) {
            e.printStackTrace();
        }
        return longSdf.format(now);
    }

    //LocalDateTime转换为Date
    public static Date convertLDTToDate(LocalDateTime time) {
        return Date.from(time.atZone(ZoneId.systemDefault()).toInstant());
    }

    //Date转换为LocalDateTime
    public static LocalDateTime convertDateToLDT(Date date) {
        return LocalDateTime.ofInstant(date.toInstant(), ZoneId.systemDefault());
    }

}