日期工具类

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;

public class DateUtil {

    /***
     * 从yyyy-MM-dd HH:mm格式转成yyyyMMddHH格式
     * @param dateStr
     * @return
     */
    public static String formatStr(String dateStr){
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm");
        try {
            Date date = simpleDateFormat.parse(dateStr);
            simpleDateFormat = new SimpleDateFormat("yyyyMMddHH");
            return simpleDateFormat.format(date);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return null;
    }

    /***
     * 获取指定日期的凌晨
     * @return
     */
    public static Date toDayStartHour(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);
        calendar.set(Calendar.MILLISECOND, 0);
        Date start = calendar.getTime();
        return start;
    }


    /***
     * 时间增加N分钟
     * @param date
     * @param minutes
     * @return
     */
    public static Date addDateMinutes(Date date,int minutes){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.MINUTE, minutes);// 24小时制
        date = calendar.getTime();
        return date;
    }

    /***
     * 时间递增N小时
     * @param hour
     * @return
     */
    public static Date addDateHour(Date date,int hour){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.HOUR, hour);// 24小时制
        date = calendar.getTime();
        return date;
    }

    /***
     * 获取时间菜单
     * @return
     */
    public static List<Date> getDateMenus(){
      
        //定义一个List<Date>集合，存储所有时间段
        List<Date> dates = new ArrayList<Date>();
        
        //循环12次
        Date date = toDayStartHour(new Date()); //凌晨
        for (int i = 0; i <12 ; i++) {
            //每次递增2小时,将每次递增的时间存入到List<Date>集合中
            dates.add(addDateHour(date,i*2));
        }

        //判断当前时间属于哪个时间范围
        Date now = new Date();
        for (Date cdate : dates) {
            //开始时间<=当前时间<开始时间+2小时
            if(cdate.getTime()<=now.getTime() && now.getTime()<addDateHour(cdate,2).getTime()){
                now = cdate;
                break;
            }
        }

        //当前需要显示的时间菜单
        List<Date> dateMenus = new ArrayList<Date>();
        for (int i = 0; i <5 ; i++) {
            dateMenus.add(addDateHour(now,i*2));
        }
        return dateMenus;
    }

    /***
     * 时间转成yyyyMMddHH
     * @param date
     * @return
     */
    public static String date2Str(Date date){
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMddHH");
        return simpleDateFormat.format(date);
    }

    public static void main(String[] args) {

        //存储数据结果
        List<Date> dateList = new ArrayList<>();

        //获取到本日的凌晨时间点
        Date startHour = toDayStartHour(new Date());

        //循环12次
        for(int i=0;i<12;i++){
            dateList.add(addDateHour(startHour,i*2));
        }

        for (Date date : dateList) {
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            String format = simpleDateFormat.format(date);
            System.out.println(format);
        }
    }
}

import java.text.SimpleDateFormat;
import java.util.*;

/**
 * 日期操作工具类
 */
public class DateUtils {
    /**
     * 日期转换-  String -> Date
     *
     * @param dateString 字符串时间
     * @return Date类型信息
     * @throws Exception 抛出异常
     */
    public static Date parseString2Date(String dateString) throws Exception {
        if (dateString == null) {
            return null;
        }
        return parseString2Date(dateString, "yyyy-MM-dd");
    }

    /**
     * 日期转换-  String -> Date
     *
     * @param dateString 字符串时间
     * @param pattern    格式模板
     * @return Date类型信息
     * @throws Exception 抛出异常
     */
    public static Date parseString2Date(String dateString, String pattern) throws Exception {
        if (dateString == null) {
            return null;
        }
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        Date date = sdf.parse(dateString);
        return date;
    }

    /**
     * 日期转换 Date -> String
     *
     * @param date Date类型信息
     * @return 字符串时间
     * @throws Exception 抛出异常
     */
    public static String parseDate2String(Date date) throws Exception {
        if (date == null) {
            return null;
        }
        return parseDate2String(date, "yyyy-MM-dd");
    }

    /**
     * 日期转换 Date -> String
     *
     * @param date    Date类型信息
     * @param pattern 格式模板
     * @return 字符串时间
     * @throws Exception 抛出异常
     */
    public static String parseDate2String(Date date, String pattern) throws Exception {
        if (date == null) {
            return null;
        }
        SimpleDateFormat sdf = new SimpleDateFormat(pattern);
        String strDate = sdf.format(date);
        return strDate;
    }

    /**
     * 获取当前日期的本周一是几号
     *
     * @return 本周一的日期
     */
    public static Date getThisWeekMonday() {
        Calendar cal = Calendar.getInstance();
        cal.setTime(new Date());
        // 获得当前日期是一个星期的第几天
        int dayWeek = cal.get(Calendar.DAY_OF_WEEK);
        if (1 == dayWeek) {
            cal.add(Calendar.DAY_OF_MONTH, -1);
        }
        // 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
        cal.setFirstDayOfWeek(Calendar.MONDAY);
        // 获得当前日期是一个星期的第几天
        int day = cal.get(Calendar.DAY_OF_WEEK);
        // 根据日历的规则，给当前日期减去星期几与一个星期第一天的差值
        cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
        return cal.getTime();
    }

    /**
     * 获取当前日期周的最后一天
     *
     * @return 当前日期周的最后一天
     */
    public static Date getSundayOfThisWeek() {
        Calendar c = Calendar.getInstance();
        int dayOfWeek = c.get(Calendar.DAY_OF_WEEK) - 1;
        if (dayOfWeek == 0) {
            dayOfWeek = 7;
        }
        c.add(Calendar.DATE, -dayOfWeek + 7);
        return c.getTime();
    }

    /**
     * 根据日期区间获取月份列表
     *
     * @param minDate 开始时间
     * @param maxDate 结束时间
     * @return 月份列表
     * @throws Exception
     */
    public static List<String> getMonthBetween(String minDate, String maxDate, String format) throws Exception {
        ArrayList<String> result = new ArrayList<>();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM");

        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);
        SimpleDateFormat sdf2 = new SimpleDateFormat(format);

        Calendar curr = min;
        while (curr.before(max)) {
            result.add(sdf2.format(curr.getTime()));
            curr.add(Calendar.MONTH, 1);
        }

        return result;
    }

    /**
     * 根据日期获取年度中的周索引
     *
     * @param date 日期
     * @return 周索引
     * @throws Exception
     */
    public static Integer getWeekOfYear(String date) throws Exception {
        Date useDate = parseString2Date(date);
        Calendar cal = Calendar.getInstance();
        cal.setTime(useDate);
        return cal.get(Calendar.WEEK_OF_YEAR);
    }

    /**
     * 根据年份获取年中周列表
     *
     * @param year 年分
     * @return 周列表
     * @throws Exception
     */
    public static Map<Integer, String> getWeeksOfYear(String year) throws Exception {
        Date useDate = parseString2Date(year, "yyyy");
        Calendar cal = Calendar.getInstance();
        cal.setTime(useDate);
        //获取年中周数量
        int weeksCount = cal.getWeeksInWeekYear();
        Map<Integer, String> mapWeeks = new HashMap<>(55);
        for (int i = 0; i < weeksCount; i++) {
            cal.get(Calendar.DAY_OF_YEAR);
            mapWeeks.put(i + 1, parseDate2String(getFirstDayOfWeek(cal.get(Calendar.YEAR), i)));
        }
        return mapWeeks;
    }

    /**
     * 获取某年的第几周的开始日期
     *
     * @param year 年分
     * @param week 周索引
     * @return 开始日期
     * @throws Exception
     */
    public static Date getFirstDayOfWeek(int year, int week) throws Exception {
        Calendar c = new GregorianCalendar();
        c.set(Calendar.YEAR, year);
        c.set(Calendar.MONTH, Calendar.JANUARY);
        c.set(Calendar.DATE, 1);

        Calendar cal = (GregorianCalendar) c.clone();
        cal.add(Calendar.DATE, week * 7);

        return getFirstDayOfWeek(cal.getTime());
    }

    /**
     * 获取某年的第几周的结束日期
     *
     * @param year 年份
     * @param week 周索引
     * @return 结束日期
     * @throws Exception
     */
    public static Date getLastDayOfWeek(int year, int week) throws Exception {
        Calendar c = new GregorianCalendar();
        c.set(Calendar.YEAR, year);
        c.set(Calendar.MONTH, Calendar.JANUARY);
        c.set(Calendar.DATE, 1);

        Calendar cal = (GregorianCalendar) c.clone();
        cal.add(Calendar.DATE, week * 7);

        return getLastDayOfWeek(cal.getTime());
    }

    /**
     * 获取当前时间所在周的开始日期
     *
     * @param date 当前时间
     * @return 开始时间
     */
    public static Date getFirstDayOfWeek(Date date) {
        Calendar c = new GregorianCalendar();
        c.setFirstDayOfWeek(Calendar.SUNDAY);
        c.setTime(date);
        c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek());
        return c.getTime();
    }

    /**
     * 获取当前时间所在周的结束日期
     *
     * @param date 当前时间
     * @return 结束日期
     */
    public static Date getLastDayOfWeek(Date date) {
        Calendar c = new GregorianCalendar();
        c.setFirstDayOfWeek(Calendar.SUNDAY);
        c.setTime(date);
        c.set(Calendar.DAY_OF_WEEK, c.getFirstDayOfWeek() + 6);
        return c.getTime();
    }
    //获得上周一的日期
    public static Date geLastWeekMonday(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(getThisWeekMonday(date));
        cal.add(Calendar.DATE, -7);
        return cal.getTime();
    }

    //获得本周一的日期
    public static Date getThisWeekMonday(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        // 获得当前日期是一个星期的第几天
        int dayWeek = cal.get(Calendar.DAY_OF_WEEK);
        if (1 == dayWeek) {
            cal.add(Calendar.DAY_OF_MONTH, -1);
        }
        // 设置一个星期的第一天，按中国的习惯一个星期的第一天是星期一
        cal.setFirstDayOfWeek(Calendar.MONDAY);
        // 获得当前日期是一个星期的第几天
        int day = cal.get(Calendar.DAY_OF_WEEK);
        // 根据日历的规则，给当前日期减去星期几与一个星期第一天的差值
        cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
        return cal.getTime();
    }

    //获得下周一的日期
    public static Date getNextWeekMonday(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(getThisWeekMonday(date));
        cal.add(Calendar.DATE, 7);
        return cal.getTime();
    }

    //获得今天日期
    public static Date getToday(){
        return new Date();
    }

    //获得本月一日的日期
    public static Date getFirstDay4ThisMonth(){
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.DAY_OF_MONTH,1);
        return calendar.getTime();
    }

    public static void main(String[] args) {
        try {
            System.out.println("本周一" + parseDate2String(getThisWeekMonday()));
            System.out.println("本月一日" + parseDate2String(getFirstDay4ThisMonth()));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}