[java]日期工具类-DateUtil

package com.coracle.worklog.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;

/**
 *  日期工具类
 * Created by lwy on 2017/9/27.
 */
public class DateUtil {
    private static DateUtil dateUtil;
    private DateUtil(){
    }
    /**
     * 获取DateUtil实例
     */
    public static DateUtil getInstance(){
        if(dateUtil==null){
            synchronized(DateUtil.class){
                if(dateUtil==null){
                    dateUtil=new DateUtil();
                }
            }
        }
        return dateUtil;
    }

    /**
     * 日期转化为对应的格式字符串
     * @param date      时间
     * @param pattern 格式化的时间格式
     *
     * @return
     */
    public String formatDate(Date date,String pattern){
        SimpleDateFormat dateFormat=new SimpleDateFormat(pattern);
        return dateFormat.format(date);
    }

    /**
     *  字符串转化为对应的日期格式
     * @param dateStr  时间字符串
     * @param format 格式化的时间格式
     * @return
     */
    public Date parseDate(String dateStr,String format) throws ParseException{
        SimpleDateFormat dateFormat=new SimpleDateFormat(format);
        return dateFormat.parse(dateStr);
    }

    /**
     *  根据传入日期，获取当前日期的本周第一天（周一）
     * @param date
     * @return
     */
    public Date getWeekHand(Date date){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(calendar.DAY_OF_WEEK, calendar.MONDAY);
        return calendar.getTime();
    }

    /**
     *  根据传入日期，获取当前日期的本周第一天（周一）
     * @param date 日期
     * @param pattern 要转化的格式
     * @return
     */
    public String getWeekHand(Date date,String pattern){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(calendar.DAY_OF_WEEK, calendar.MONDAY);
        return formatDate(calendar.getTime(),pattern);
    }

    /**
     *  根据传入日期，获取当前日期的本周最后一天（周日）
     * @param date 日期
     * @return
     */
    public Date getWeekLast(Date date){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(calendar.DAY_OF_WEEK, calendar.MONDAY);
        calendar.set(Calendar.DATE, calendar.get(calendar.DATE) + 6);
        return calendar.getTime();
    }

    /**
     *  根据传入日期，获取当前日期的本周最后一天（周日）
     * @param date 日期
     * @param pattern 要转化的格式
     * @return
     */
    public String getWeekLast(Date date,String pattern){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(calendar.DAY_OF_WEEK, calendar.MONDAY);
        calendar.set(Calendar.DATE, calendar.get(calendar.DATE) + 6);
        return formatDate(calendar.getTime(),pattern);
    }

    /**
     *  日期加法
     * @param dateStr 时间字符串格式
     * @param day     要增加的天数
     * @param pattern  时间格式
     * @return
     */
    public String addDate(String dateStr,int day,String pattern) throws ParseException{
        Date date = parseDate(dateStr, pattern);
        Calendar calendar=Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.get(Calendar.DAY_OF_MONTH)+day);
        return formatDate(calendar.getTime(),pattern);
    }

    /**
     *  日期加法
     * @param date 日期
     * @param day     要增加的天数
     * @return
     */
    public Date addDate(Date date,int day){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.get(Calendar.DAY_OF_MONTH)+day);
        return calendar.getTime();
    }

    /**
     *  日期加法
     * @param date 日期
     * @param day     要增加的天数
     * @param pattern 日期格式
     * @return
     */
    public String addDate(Date date,int day,String pattern){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.get(Calendar.DAY_OF_MONTH)+day);
        return formatDate(calendar.getTime(),pattern);
    }

    /**
     *  日期减法
     * @param dateStr 时间字符串格式
     * @param day     要减少的天数
     * @param pattern  时间格式
     * @return
     */
    public String minusDate(String dateStr,int day,String pattern) throws ParseException{
        Date date = parseDate(dateStr,pattern);
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.get(Calendar.DAY_OF_MONTH)-day);
        return formatDate(calendar.getTime(),pattern);
    }

    /**
     *  日期减法
     * @param date  时间
     * @param day  要减少的天数
     * @return
     */
    public Date minusDate(Date date,int day) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.get(Calendar.DAY_OF_MONTH)-day);
        return calendar.getTime();
    }

    /**
     *  日期减法
     * @param date  时间
     * @param day  要减少的天数
     * @return
     */
    public String minusDate(Date date,int day,String pattern) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.set(Calendar.DAY_OF_MONTH, calendar.get(Calendar.DAY_OF_MONTH)-day);
        return formatDate(calendar.getTime(),pattern);
    }

    public String getWeekOfMonth(Date date){
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int weekOfMonth = calendar.get(Calendar.WEEK_OF_MONTH);
        return String.format(Locale.SIMPLIFIED_CHINESE,"%tb份第%d周",calendar.getTime(),weekOfMonth);
    }

    public String getWeekOfMonth(String dateStr,String pattern) throws ParseException{
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(parseDate(dateStr,pattern));
        calendar.setFirstDayOfWeek(Calendar.MONDAY);
        int weekOfMonth = calendar.get(Calendar.WEEK_OF_MONTH);
        return String.format(Locale.SIMPLIFIED_CHINESE,"%tb份第%d周",calendar.getTime(),weekOfMonth);
    }

    public static void main(String[] args) {
        SimpleDateFormat dateFormat=new SimpleDateFormat("yyyy-MM-dd");
        try {
            System.out.println(dateFormat.format(DateUtil.getInstance().getWeekHand(new Date())));
            System.out.println(dateFormat.format(DateUtil.getInstance().getWeekLast(new Date())));
            System.out.println(DateUtil.getInstance().minusDate("2017-09-27",2,"yyyy-MM-dd"));
            System.out.println( DateUtil.getInstance().addDate("2017-09-27",2,"yyyy-MM-dd"));
            System.out.println(DateUtil.getInstance().getWeekOfMonth(new Date()));
        }catch (Exception ex){
            ex.printStackTrace();
        }
    }
}