时间处理工具类DateUtils

package com.cs.common.util;

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

/**
 * <p>
 * com.cs.common.util.DateUtils
 * </p>
 * Function List:<br>
 * 常用的时间操作
 * 
 * @author 
 * @version Revision:1.0 Date: 2010-9-15 下午05:44:00
 */
public class DateUtils {
	/**
	 * 计算两个日期之间的差距天数
	 * 
	 * @param a
	 * @param b
	 * @return
	 */
	public static int cutTwoDateToDay(Date a, Date b) {
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
		Calendar calendar = Calendar.getInstance();
		int theday = 0;
		try {
			Date beginDate = format.parse(format.format(a));
			Date endDate = format.parse(format.format(b));

			calendar.setTime(beginDate);
			long begin = calendar.getTimeInMillis();
			calendar.setTime(endDate);
			long end = calendar.getTimeInMillis();

			theday = (int) ((end - begin) / (86400000));
		} catch (ParseException e) {
			e.printStackTrace();
		}
		return theday;
	}

	/**
	 * 将数字型的时间转为字符串（80 -> 01:20）
	 * 
	 * @param time
	 * @return
	 */
	public static String intToTimeString(int time) {
		String hour = String.valueOf(time / 60);
		String minute = String.valueOf(time - time / 60 * 60);

		if (hour.length() < 2) {
			hour = "0" + hour;
		}
		if (minute.length() < 2) {
			minute = "0" + minute;
		}
		return hour + ":" + minute;
	}

	/**
	 * 取出两个时间出较大的时间
	 * 
	 * @param a
	 * @param b
	 * @return
	 */
	public static Date MaxDate(Date a, Date b) {
		if (a.before(b)) {
			return b;
		} else {
			return a;
		}
	}

	/**
	 * 取出两个时间出较小的时间
	 * 
	 * @param a
	 * @param b
	 * @return
	 */
	public static Date MinDate(Date a, Date b) {
		if (a.before(b)) {
			return a;
		} else {
			return b;
		}
	}

	/**
	 * 计算给定日期是星期几
	 * 
	 * @param date
	 * @return
	 */
	public static int getWeekOfDate(Date date) {
		java.util.Calendar cal = java.util.Calendar.getInstance();
		cal.setTime(date);
		int w = cal.get(java.util.Calendar.DAY_OF_WEEK) - 1;
		if (w == 0)
			w = 7;
		return w;
	}

	/**
	 * 格式化日期
	 * 
	 * @param date
	 * @param pattern
	 * @return
	 */
	public static String formatDate(Date date, String pattern) {
		SimpleDateFormat format = new SimpleDateFormat(pattern);
		return format.format(date);
	}

	/**
	 * 根据给定日期字符串和日期格式 创建日期
	 * 
	 * @param dateString
	 * @param pattern
	 * @return
	 * @throws ParseException
	 */
	public static Date createDate(String dateString, String pattern) throws ParseException {
		SimpleDateFormat format = new SimpleDateFormat(pattern);
		return format.parse(dateString);
	}

	public static void main(String[] args) throws ParseException {
		System.out.println(formatDate(new Date(), "yyyy-MM-dd"));
	}
}