java 常用的时间方法工具类

package com.xxx.xxx.xxx;

import java.sql.Timestamp;
import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

public class DateUtil {

	/**
	 * 获取当天开始时间
	 */
	public static Date getStartDay() {
		Calendar calendar = Calendar.getInstance();
		calendar.set(Calendar.HOUR_OF_DAY, 0);
		calendar.set(Calendar.MINUTE, 0);
		calendar.set(Calendar.SECOND, 0);
		calendar.set(Calendar.MILLISECOND, 0);
		return calendar.getTime();
	}

	/**
	 * 获取当天结束时间
	 */
	public static Date getEndDay() {
		Calendar calendar = Calendar.getInstance();
		calendar.set(Calendar.HOUR_OF_DAY, 23);
		calendar.set(Calendar.MINUTE, 59);
		calendar.set(Calendar.SECOND, 59);
		calendar.set(Calendar.MILLISECOND, 0);
		return calendar.getTime();
	}
	
	/**
	 *
	 * 获取第二天凌晨零点时间
	 * @return
	 */
	public static Date getNextDayStart() {
		Calendar calendar = Calendar.getInstance();
		calendar.add(Calendar.DAY_OF_MONTH, 1);
		calendar.set(Calendar.HOUR_OF_DAY, 0);
		calendar.set(Calendar.MINUTE, 0);
		calendar.set(Calendar.SECOND, 0);
		calendar.set(Calendar.MILLISECOND, 0);
		return calendar.getTime();
	}

	/**
	 * 获取本周的第一天
	 * @return String
	 **/
	public static Date getWeekStart() {
		Calendar calendar = Calendar.getInstance();
		calendar.setFirstDayOfWeek(Calendar.MONDAY);
		calendar.set(Calendar.HOUR_OF_DAY, 0);
		calendar.set(Calendar.MINUTE, 0);
		calendar.set(Calendar.SECOND, 0);
		calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
		return calendar.getTime();
	}

	/**
	 * 获取本周的最后一天
	 * @return String
	 **/
	public static Date getWeekEnd() {
		Calendar calendar = Calendar.getInstance();
		calendar.setFirstDayOfWeek(Calendar.MONDAY);
		calendar.set(Calendar.HOUR_OF_DAY, 23);
		calendar.set(Calendar.MINUTE, 59);
		calendar.set(Calendar.SECOND, 59);
		calendar.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);
		return calendar.getTime();
	}

	/**
	 *
	 * 获取下周开始时间
	 * @return
	 */
	public static Date getNextWeekStart() {
		Calendar cal = Calendar.getInstance();
		cal.setTime(getWeekStart());
		cal.add(Calendar.DATE, 7);
		return cal.getTime();
	}

	/**
	 * 获取当月开始时间
	 */
	public static Date getStartMonth() {
		Calendar calendar = Calendar.getInstance();
		calendar.set(Calendar.DAY_OF_MONTH, 1);
		calendar.set(Calendar.HOUR_OF_DAY, 0);
		calendar.set(Calendar.MINUTE, 0);
		calendar.set(Calendar.SECOND, 0);
		calendar.set(Calendar.MILLISECOND, 0);

		return calendar.getTime();
	}

	/**
	 * 获取当月结束时间
	 */
	public static Date getEndMonth() {
		Calendar calendar = Calendar.getInstance();
		calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
		calendar.set(Calendar.HOUR_OF_DAY, 23);
		calendar.set(Calendar.MINUTE, 59);
		calendar.set(Calendar.SECOND, 59);
		calendar.set(Calendar.MILLISECOND, 0);
		return calendar.getTime();
	}

	/**
	 * 获取下个月开始时间
	 */
	public static Date getNextMonthStart() {
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(getStartMonth());
		calendar.add(Calendar.MONTH, 1);
		return calendar.getTime();
	}
/**
	 * 获取某个date的年份
	 * @param date
	 * @return
	 */
	public static int getYear(Date date) {
		Calendar c = Calendar.getInstance();
		c.setTime(date);
		return c.get(Calendar.YEAR);
	}

	/**
	 * 获取某个date的月份
	 * @param date
	 * @return
	 */
	public static int getMonth(Date date) {
		Calendar c = Calendar.getInstance();
		c.setTime(date);
		return c.get(Calendar.MONTH) + 1;
	}

	/**
	 * 获取某个date的day
	 * @param date
	 * @return
	 */
	public static int getDay(Date date) {
		Calendar c = Calendar.getInstance();
		c.setTime(date);
		return c.get(Calendar.DAY_OF_MONTH);
	}
	
	/**
	 * 获取两个时间的时间差
	 * @param before
	 * @param after
	 * @param flag 0:秒，1:分，2:时，3:天
	 * @return
	 */
	public static int getDiffNum(Date before, Date after, int flag) {
		if (before == null || after == null) {
			return 0;
		}
		long timeInterval = after.getTime() - before.getTime();
		switch (flag) {
		case 0:// 秒
			return (int) ((timeInterval / 1000));
		case 1:// 分
			return (int) ((timeInterval / (60 * 1000)));
		case 2:// 时
			return (int) (timeInterval / (60 * 60 * 1000));
		case 3:// 天
			return (int) (timeInterval / (60 * 60 * 1000 * 24));
		}
		return 0;
	}
	/**
	 * 获取从当前日期指定分钟以前的日期
	 * @return
	 */
	public static Date getDateBeforeMinute(int beforeMinute) {
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(new Date());
		int minute = calendar.get(Calendar.MINUTE);
		calendar.set(Calendar.MINUTE, minute - beforeMinute);
		return calendar.getTime();
	}