java--Date时间工具类

package date;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
/**
 *@author: youthcool
 *@date: 2019/9/6
 *@description: 时间工具类
 */
public class DateUtils {
    /**
     * @param start 开始日期
     * @param end   结束如期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 比较两个时间之前相差的天数(忽略小时, 分, 秒的影响)
     */
    public static Integer diffDay(Date start, Date end) {
        if (start == null || end == null) {
            return null;
        }
        return (int) ((getDate(end).getTimeInMillis() - getDate(start).getTimeInMillis()) / (1000 * 3600 * 24));
    }

    /**
     * @param date 开始日期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 获取日期部分的时间（去除时间部分）
     */
    public static Calendar getDate(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return getDate(calendar);
    }

    /**
     * @param str  字符串时间格式--"2019-9-6"
     * @param pattern 转成什么格式
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description
     */
    public static Date changeStringDateToFormat(String str, String pattern){
        SimpleDateFormat df = new SimpleDateFormat(pattern);
        try {
            return df.parse(str);
        } catch (ParseException e) {
            e.printStackTrace();
            return new Date();
        }
    }
    /**
     * @param calendar Calendar格式
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 获取日期部分的时间（去除时间部分）
     */
    public static Calendar getDate(Calendar calendar) {
        calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return calendar;
    }
    /**
     * @param date   指定日期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description  获取指定时间再本周的索引，周一为0
     */
    public static int getIndexOfDate(Date date) {
        if (date == null) return -1;
        Calendar instance = Calendar.getInstance();
        instance.setTime(date);
        /**
         * 该方法返回的值1-7，周日为1，周六为7，周一为2
         */
        int weekIndex = instance.get(Calendar.DAY_OF_WEEK);
        if (weekIndex == 1) weekIndex = 8;
        return weekIndex - 2;
    }
    /**
     * @param date   指定日期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 返回指定时间所在周的最后一天
     */
    public static Date getWeekLastDay(Date date) {
        if (date == null) return null;
        Calendar instance = Calendar.getInstance();
        instance.setTime(date);
        /**
         * 该方法返回的值1-7，周日为1，周六为7，周一为2
         */
        int weekIndex = instance.get(Calendar.DAY_OF_WEEK);
        if (weekIndex == 1) weekIndex = 8;
        instance.add(Calendar.DAY_OF_YEAR, 8 - weekIndex);
        instance.set(Calendar.HOUR_OF_DAY, 23);
        instance.set(Calendar.MINUTE, 59);
        instance.set(Calendar.SECOND, 59);
        instance.set(Calendar.MILLISECOND, 999);
        return instance.getTime();
    }
    /**
     * @param date   指定日期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 返回指定时间所在周的第一天
     */
    public static Date getWeekFirstDay(Date date) {
        if (date == null) return null;
        Calendar instance = Calendar.getInstance();
        instance.setTime(date);
        /**
         * 该方法返回的值1-7，周日为1，周六为7，周一为2
         */
        int weekIndex = instance.get(Calendar.DAY_OF_WEEK);
        if (weekIndex == 1) weekIndex = 8;
        instance.add(Calendar.DAY_OF_YEAR, 2 - weekIndex);
        instance.set(Calendar.HOUR_OF_DAY, 0);
        instance.set(Calendar.MINUTE, 0);
        instance.set(Calendar.SECOND, 0);
        instance.set(Calendar.MILLISECOND, 0);
        return instance.getTime();
    }
    /**
     * @param date   指定日期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 获取指定日期当月的最后一天(2019/9/6->Tue Oct 01 00:00:00 CST 2019)
     */
    public static Date getLastDayOfGiven(Date date) {
        if (date == null) return null;
        return addSeconds(getFirstDayOfNextMonth(date), -1);
    }
    /**
     * @param date   指定日期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 获取指定日期下个月的第一天
     */
    public static Date getFirstDayOfNextMonth(Date date) {
        SimpleDateFormat sdf = new SimpleDateFormat(DateFormat.DATE_FORMAT);
        String dateStr = sdf.format(date);
        try {
            date = sdf.parse(dateStr);
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(date);
            calendar.set(Calendar.DAY_OF_MONTH, 1);
            calendar.add(Calendar.MONTH, 1);
            return calendar.getTime();
        } catch (ParseException e) {
            e.printStackTrace();
            return null;
        }
    }
    /**
     * @param startDay 开始日期
     * @param endDay   结束日期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 计算两个时间之间相隔天数
     */
    public static int getDays(Date startDay, Date endDay) {
        if (startDay.after(endDay)) {
            Date start = startDay;
            startDay = endDay;
            endDay = start;
        }
        long start = startDay.getTime();
        long end = endDay.getTime();
        long ei = end - start;
        return (int) (ei / (1000 * 60 * 60 * 24));
    }
    /**
     * @param date 指定日期
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 获取指定日期当月的第一天
     */
    public static Date getFirstDayOfGivenMonth(Date date) {
        SimpleDateFormat sdf = new SimpleDateFormat(DateFormat.DATE_FORMAT);
        String dateStr = sdf.format(date);
        try {
            date = sdf.parse(dateStr);
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(date);
            calendar.set(Calendar.DAY_OF_MONTH, 1);
            calendar.add(Calendar.MONTH, 0);
            return calendar.getTime();
        } catch (ParseException e) {
            e.printStackTrace();
            return null;
        }
    }
    /**
     * @param date   时间
     * @param second 几秒钟
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 在指定时间上添加秒
     */
    public static Date addSeconds(Date date, int second) {
        if (date == null) return null;
        Calendar instance = Calendar.getInstance();
        instance.setTime(date);
        instance.add(Calendar.SECOND, second);
        return instance.getTime();
    }
    /**
     * @param date   时间
     * @param minute 几分钟
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 在指定时间上添加分钟
     */
    public static Date addMinutes(Date date, int minute) {
        if (date == null) return null;
        Calendar instance = Calendar.getInstance();
        instance.setTime(date);
        instance.add(Calendar.MINUTE, minute);
        return instance.getTime();
    }
    /**
     * @param date   时间
     * @param hour 几小时
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 在指定时间上添加小时
     */
    public static Date addHours(Date date, int hour) {
        if (date == null) return null;
        Calendar instance = Calendar.getInstance();
        instance.setTime(date);
        instance.add(Calendar.HOUR_OF_DAY, hour);
        return instance.getTime();
    }
    /**
     * @param date   时间
     * @param millisecond 几毫秒
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 在指定时间上添加毫秒
     */
    public static Date addMillisecond(Date date, int millisecond) {
        if (date == null) return null;
        Calendar instance = Calendar.getInstance();
        instance.setTime(date);
        instance.add(Calendar.MILLISECOND, millisecond);
        return instance.getTime();
    }
    /**
     * @return java.util.Date
     * @author youthcool
     * @date 2019/8/27
     * @description 获取上一个月的结束时间
     */
    public static Date getEndOfLastMonth(){
        SimpleDateFormat simpleDateFormat=new SimpleDateFormat(DateFormat.DATETIME_FORMAT);
        Calendar calendar=Calendar.getInstance();
        calendar.add(Calendar.MONTH, -1);
        int lastMonthMaxDay=calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
        calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), lastMonthMaxDay, 23, 59, 59);
        return calendar.getTime();
    }
    /**
     * @param date     时间
     * @param dateType 转化类型
     * @param month    加几个月
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/3
     * @description 在某个时间上加几个月
     */
    public static Date addMonth(Date date, String dateType, int month) {
        Date nowDate = null;
        SimpleDateFormat format = new SimpleDateFormat(dateType);
        try {
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(date);
            calendar.add(Calendar.MONTH, month);
            int lastMonthMaxDay = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
            calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), lastMonthMaxDay, 23, 59, 59);
            String now = format.format(calendar.getTime());
            nowDate=format.parse(now);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return nowDate;
    }
    /**
     * @param date 日期
     * @param days 天数
     * @return java.util.Date
     * @author youthcool
     * @date 2019/9/6
     * @description 在指定时间上添加天数
     */
    public static Date addDays(Date date, int days) {
        if (date == null) return null;
        Calendar instance = Calendar.getInstance();
        instance.setTime(date);
        instance.add(Calendar.DAY_OF_YEAR, days);
        return instance.getTime();
    }
    /**
     * @author youth
     * @date 2019/9/4
     * @description 日期格式常量接口
     */
    public interface DateFormat{
        String DATE_FORMAT="yyyy-MM-dd";

        String HOUR_MINUTE="hh:mm";

        String DATE_FORMAT_EN = "dd/MM/yyyy";

        String DATETIME_FORMAT ="yyyy-MM-dd HH:mm:ss.SSS";

        String DATE_MOBNTH = "yyyy-MM";

        String DATE_DAY = "dd";

        String WITHOUT_SECOND_FORMAT="yyyy-MM-dd HH:mm";

        String WITHOUT_SECOND_FORMAT_EN="dd/MM/yyyy HH:mm";

        String HOUR_OF_DAY_MINUTE="HH:mm";
    }
}