java常用的日期函数

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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 DataUtil {
	
	/**
	 * 返回当前日期所在月份的天数
	 */
	public static List<Date> getAllTheDateOftheMonth(Date date) {
		List<Date> list = new ArrayList<Date>();
		Calendar cal = Calendar.getInstance();
		cal.setTime(date);
		cal.set(Calendar.DATE, 1);
		int month = cal.get(Calendar.MONTH);
		while (cal.get(Calendar.MONTH) == month) {
			list.add(cal.getTime());
			cal.add(Calendar.DATE, 1);
		}
		return list;
	}
	
	/**
	 * 获取前XX天的时间
	 */
	public static Date getPastDate(int pastDay) throws ParseException {
		Calendar c = Calendar.getInstance();
		c.set(Calendar.DAY_OF_YEAR, c.get(Calendar.DAY_OF_YEAR) - pastDay);
		Date today = c.getTime();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String result = sdf.format(today);
		Date date = sdf.parse(result);
		return date;
	 }
	
	/**
	 * 根据时间（变量）获取未来XX天的时间
	 */
	public static Date getFutureDate(Date thisDay, int futureDay) throws ParseException {
		Calendar c = Calendar.getInstance();
		c.setTime(thisDay);
		c.set(Calendar.DAY_OF_YEAR, c.get(Calendar.DAY_OF_YEAR) + futureDay);
		Date future = c.getTime();
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String result = sdf.format(future);
		Date date = sdf.parse(result);
		return date;
	}
	
	/**
	 * 根据系统当前时间获取未来XX天的时间
	 */
	public static Date getFutureDate(int futureDay) throws ParseException {
		Calendar c = Calendar.getInstance();
		c.set(Calendar.DAY_OF_YEAR, c.get(Calendar.DAY_OF_YEAR) + futureDay);
		Date today = c.getTime(); // 系统当前时间
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String result = sdf.format(today);
		Date date = sdf.parse(result);
		return date;
	}/**
	 * 获取该日期的周一
	 * 
	 * @param date
	 * @return
	 */
	public static Date getThisWeekMonday(Date date) {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy-MM-dd");
		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);
		Date param = cal.getTime();
		String result = sdf.format(param) + " 00:00:00";
		try {
			return sdf2.parse(result);
		} catch (ParseException e) {
			LoggerConfig.systemLogger.error("日期格式转换异常", e);
		}
		return null;
	}


	/**
	 * 获取前XX分钟的时间
	 */
	public static Date getPastMinute(Date newDate, int pastMinute)
			throws ParseException {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Calendar c = Calendar.getInstance();
		c.setTime(newDate);
		c.set(c.get(Calendar.YEAR), (c.get(Calendar.MONTH)),
				c.get(Calendar.DAY_OF_MONTH), c.get(Calendar.HOUR_OF_DAY),
				(c.get(Calendar.MINUTE) - pastMinute), c.get(Calendar.SECOND));
		Date past = c.getTime();
		String result = sdf.format(past);
		return sdf.parse(result);
	}
	
	/**
	 * 获取未来XX小时后的时间
	 */
	public static Date getFurterByHour(Date date, int hours) throws ParseException{
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Calendar c = Calendar.getInstance();
		int fHour = c.get(Calendar.HOUR_OF_DAY) + hours;
		c.setTime(date);
		c.set(c.get(Calendar.YEAR), 
				c.get(Calendar.MONTH), 
				c.get(Calendar.DAY_OF_MONTH), 
				fHour, 
				c.get(Calendar.MINUTE), 
				c.get(Calendar.SECOND));
		Date further = c.getTime();
		String result = sdf.format(further);
		return sdf.parse(result);
	}
	
	/**
	 * 获取当前日期月份的第一天
	 */
	public static Date getFirstDayByMonth(Date date) {
    	Calendar c = Calendar.getInstance();
    	c.setTime(date);
    	c.add(Calendar.MONTH, 0);
    	c.set(Calendar.DAY_OF_MONTH, 1);
    	return c.getTime();
    }

}