可能不是很完善，不喜勿噴

package com.gzy.health.utils;

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

/**
 * 日期操作工具類
 */
public class DateUtils {
    /**
     * 日期轉(zhuǎn)換-  String -> Date
     *
     * @param dateString 字符串時間
     * @return Date類型信息
     * @throws Exception 拋出異常
     */
    public static Date parseString2Date(String dateString) throws Exception {
        if (dateString == null) {
            return null;
        }
        return parseString2Date(dateString, "yyyy-MM-dd");
    }

    /**
     * 日期轉(zhuǎn)換-  String -> Date
     *
     * @param dateString 字符串時間
     * @param pattern    格式模板
     * @return Date類型信息
     * @throws Exception 拋出異常
     */
    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;
    }

    /**
     * 日期轉(zhuǎn)換 Date -> String
     *
     * @param date Date類型信息
     * @return 字符串時間
     * @throws Exception 拋出異常
     */
    public static String parseDate2String(Date date) throws Exception {
        if (date == null) {
            return null;
        }
        return parseDate2String(date, "yyyy-MM-dd");
    }

    /**
     * 日期轉(zhuǎn)換 Date -> String
     *
     * @param date    Date類型信息
     * @param pattern 格式模板
     * @return 字符串時間
     * @throws Exception 拋出異常
     */
    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;
    }

    /**
     * 獲取當(dāng)前日期的本周一是幾號
     *
     * @return 本周一的日期
     */
    public static Date getThisWeekMonday() {
        Calendar cal = Calendar.getInstance();
        cal.setTime(new Date());
        // 獲得當(dāng)前日期是一個星期的第幾天
        int dayWeek = cal.get(Calendar.DAY_OF_WEEK);
        if (1 == dayWeek) {
            cal.add(Calendar.DAY_OF_MONTH, -1);
        }
        // 設(shè)置一個星期的第一天，按中國的習(xí)慣一個星期的第一天是星期一
        cal.setFirstDayOfWeek(Calendar.MONDAY);
        // 獲得當(dāng)前日期是一個星期的第幾天
        int day = cal.get(Calendar.DAY_OF_WEEK);
        // 根據(jù)日歷的規(guī)則，給當(dāng)前日期減去星期幾與一個星期第一天的差值
        cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
        return cal.getTime();
    }

    /**
     * 獲取當(dāng)前日期周的最后一天
     *
     * @return 當(dāng)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();
    }

    /**
     * 根據(jù)日期區(qū)間獲取月份列表
     *
     * @param minDate 開始時間
     * @param maxDate 結(jié)束時間
     * @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;
    }

    /**
     * 根據(jù)日期獲取年度中的周索引
     *
     * @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);
    }

    /**
     * 根據(jù)年份獲取年中周列表
     *
     * @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);
        //獲取年中周數(shù)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;
    }

    /**
     * 獲取某年的第幾周的開始日期
     *
     * @param year 年分
     * @param week 周索引
     * @return 開始日期
     * @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());
    }

    /**
     * 獲取某年的第幾周的結(jié)束日期
     *
     * @param year 年份
     * @param week 周索引
     * @return 結(jié)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());
    }

    /**
     * 獲取當(dāng)前時間所在周的開始日期
     *
     * @param date 當(dāng)前時間
     * @return 開始時間
     */
    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();
    }

    /**
     * 獲取當(dāng)前時間所在周的結(jié)束日期
     *
     * @param date 當(dāng)前時間
     * @return 結(jié)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();
    }
    //獲得上周一的日期
    public static Date geLastWeekMonday(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(getThisWeekMonday(date));
        cal.add(Calendar.DATE, -7);
        return cal.getTime();
    }

    //獲得本周一的日期
    public static Date getThisWeekMonday(Date date) {
        Calendar cal = Calendar.getInstance();
        cal.setTime(date);
        // 獲得當(dāng)前日期是一個星期的第幾天
        int dayWeek = cal.get(Calendar.DAY_OF_WEEK);
        if (1 == dayWeek) {
            cal.add(Calendar.DAY_OF_MONTH, -1);
        }
        // 設(shè)置一個星期的第一天，按中國的習(xí)慣一個星期的第一天是星期一
        cal.setFirstDayOfWeek(Calendar.MONDAY);
        // 獲得當(dāng)前日期是一個星期的第幾天
        int day = cal.get(Calendar.DAY_OF_WEEK);
        // 根據(jù)日歷的規(guī)則，給當(dāng)前日期減去星期幾與一個星期第一天的差值
        cal.add(Calendar.DATE, cal.getFirstDayOfWeek() - day);
        return cal.getTime();
    }

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

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

    //獲得本月一日的日期
    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();
        }
    }
}