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     博客原文：点击阅读     datecalendar getInstancecalendardatecalendarcalendarcalendarcalendar@param @return   老是忘，还是记录下 -_-||

package zjhuiwan.cn.helper;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;import java.util.GregorianCalendar;/** * Created by on 2019/4/17. */public class WeekMonthUtil {    /**     * leftDate是否在rightDate之前或相等     *      * @param leftDate     * @param rightDate     * @return     */    public static Boolean beforeOrEquals(Date leftDate, Date rightDate) {        return leftDate.before(rightDate) || leftDate.equals(rightDate);    }    /**     * leftDate是否在rightDate之后或相等     *      * @param leftDate     * @param rightDate     * @return     */    public static Boolean afterOrEquals(Date leftDate, Date rightDate) {        return leftDate.after(rightDate) || leftDate.equals(rightDate);    }    /**     * 获取传入时间的当天0点     *      * @param date     * @return     */    public static Date getDateZero(Date date) {        Calendar calendar = Calendar.getInstance();        calendar.setTime(date);        calendar.set(Calendar.HOUR_OF_DAY, 0);        calendar.set(Calendar.MINUTE, 0);        calendar.set(Calendar.SECOND, 0);        return calendar.getTime();    }    /**     * 获取传入时间的当天最后一秒     *      * @param date     * @return     */    public static Date getDateLast(Date date) {        Calendar calendar = Calendar.getInstance();        calendar.setTime(getDateZero(date));        calendar.add(Calendar.DAY_OF_MONTH, 1); // 一天后的时间        calendar.add(Calendar.SECOND, -1);        return calendar.getTime();    }    /**     * 格式化日期为字符串     *     * @param date     * @return     */    public static String getDateStr(Date date, String fmt) {        SimpleDateFormat sdf = new SimpleDateFormat(fmt);        return sdf.format(date);    }    /**     * 格式化字符串为日期     *     * @param date     * @return     */    public static Date getDateLast(String date, String fmt) {        SimpleDateFormat sdf = new SimpleDateFormat(fmt);        Date dateSdf = null;        try {            dateSdf = sdf.parse(date);        } catch (ParseException e) {            e.printStackTrace();        }        return dateSdf;    }    /**     * 获得本周一与当前日期相差的天数     *      * @param date     * @return     */    public static int getMondayPlus(Date date) {        Calendar cd = Calendar.getInstance();        cd.setTime(date);        int dayOfWeek = cd.get(Calendar.DAY_OF_WEEK);        if (dayOfWeek == 1) {            return -6;        } else {            return 2 - dayOfWeek;        }    }    /**     * 获得当前周的周一     *      * @param date     * @return     */    public static Date getCurrentMonday(Date date) {        int mondayPlus = getMondayPlus(date);        GregorianCalendar currentDate = new GregorianCalendar();        currentDate.add(GregorianCalendar.DATE, mondayPlus);        Date monday = currentDate.getTime();        return monday;    }    /**     * 获得当前周的周日     *      * @param date     * @return     */    public static Date getPreviousSunday(Date date) {        int mondayPlus = getMondayPlus(date);        GregorianCalendar currentDate = new GregorianCalendar();        currentDate.add(GregorianCalendar.DATE, mondayPlus + 6);        Date monday = currentDate.getTime();        return monday;    }    /**     * 获得当前月的开始日期     *      * @param date     * @return     */    public static Date getMinMonthDate(Date date) {        Calendar calendar = Calendar.getInstance();        calendar.setTime(date);        calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));        return calendar.getTime();    }    /**     * 获得当前月的结束日期     *      * @param date     * @return     */    public static Date getMaxMonthDate(Date date) {        Calendar calendar = Calendar.getInstance();        calendar.setTime(date);        calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));        return calendar.getTime();    }    /**     * 获取上N个月     *      * @return     */    public static Date getPreMonth(Date date, int n) {        Calendar calendar = Calendar.getInstance();        calendar.setTime(date);        calendar.add(Calendar.MONTH, -1 * n);        return calendar.getTime();    }    /**     *      * 获取下N个月.     *      * @return     */    public static Date getNextMonth(Date date, int n) {        Calendar calendar = Calendar.getInstance();        calendar.setTime(date);        calendar.add(Calendar.MONTH, n);        return calendar.getTime();    }}

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