JAVA各种时间类型的取得

package com.hello.test;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import org.apache.log4j.Logger;

public class DateUtil {

	private static Logger log = Logger.getLogger(DateUtil.class);

	private static String defaultDatePattern = null;

	private static String timePattern = "HH:mm";

	public static Date getSystemTime() {
		Calendar now = Calendar.getInstance();
		return now.getTime();

	}

	public static synchronized String getDatePattern() {
		Locale locale = Locale.CHINA; // LocaleContextHolder.getLocale();

		try {
			defaultDatePattern = ResourceBundle.getBundle("yyyy-MM-dd", locale).getString("date.format");
		} catch (MissingResourceException mse) {
			defaultDatePattern = "yyyy-MM-dd";
		}

		return defaultDatePattern;
	}

	public static final String getDate(Date aDate) {
		SimpleDateFormat df = null;
		String returnValue = "";

		if (aDate != null) {
			df = new SimpleDateFormat(getDatePattern());
			returnValue = df.format(aDate);
		}

		return (returnValue);
	}

	public static final Date convertStringToDate(String aMask, String strDate) {
		SimpleDateFormat df = null;
		Date date = null;
		df = new SimpleDateFormat(aMask);

		if (log.isDebugEnabled()) {
			log.debug("converting '" + strDate + "' to date with mask '" + aMask + "'");
		}

		try {
			date = df.parse(strDate);
		} catch (ParseException pe) {
			log.error("ParseException: " + pe);
		}

		return (date);
	}

	public static String getTimeNow(Date theTime) {
		return getDateTime(timePattern, theTime);
	}

	public static Calendar getToday() throws ParseException {
		Date today = new Date();
		SimpleDateFormat df = new SimpleDateFormat(getDatePattern());

		// This seems like quite a hack (date -> string -> date),
		// but it works ;-)
		String todayAsString = df.format(today);
		Calendar cal = new GregorianCalendar();
		cal.setTime(convertStringToDate(todayAsString));

		return cal;
	}

	public static Date getMonday(Date date) {
		Calendar c = Calendar.getInstance();
		c.setTime(date);
		if (c.get(Calendar.DAY_OF_WEEK) == 1) {
			date = DateUtil.addDays(date, -7);
			c.setTime(date);
		}

		c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
		String mondayString = DateUtil.format(c.getTime(), "yyyy-MM-dd");
		mondayString = mondayString + " 00:00:00";
		return convertStringToDate("yyyy-MM-dd HH:mm:ss", mondayString);
	}

	public static Date getFriday(Date date) {
		Calendar c = Calendar.getInstance();
		c.setTime(date);
		c.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);
		String fridayString = format(c.getTime(), "yyyy-MM-dd");
		fridayString = fridayString + " 23:59:59";
		return convertStringToDate("yyyy-MM-dd HH:mm:ss", fridayString);

	}

	public static final String getDateTime(String aMask, Date aDate) {
		SimpleDateFormat df = null;
		String returnValue = "";

		if (aDate == null) {
			log.error("aDate is null!");
		} else {
			df = new SimpleDateFormat(aMask);
			returnValue = df.format(aDate);
		}

		return (returnValue);
	}

	public static final String convertDateToString(Date aDate) {
		return getDateTime(getDatePattern(), aDate);
	}

	public static Date convertStringToDate(String strDate) {
		Date aDate = null;

		try {
			if (log.isDebugEnabled()) {
				log.debug("converting date with pattern: " + getDatePattern());
			}

			aDate = convertStringToDate(getDatePattern(), strDate);
		} catch (Exception pe) {
			log.error("Could not convert '" + strDate + "' to a date, throwing exception");

		}

		return aDate;
	}

	public static int dayDiff(Date first, Date second) {

		long msPerDay = 1000 * 60 * 60 * 24;
		long diff = (first.getTime() / msPerDay) - (second.getTime() / msPerDay);

		Long convertLong = new Long(diff);
		return convertLong.intValue();
	}

	public static long dayDiffMilSecond(Date first, Date second) {

		long diff = first.getTime() - second.getTime();
		Long convertLong = new Long(diff);
		return convertLong;
	}

	public static String format(Date date, String pattern) {
		if (date == null)
			return "";
		SimpleDateFormat formatter = new SimpleDateFormat(pattern);
		return formatter.format(date);
	}

	static public final Date addDays(Date target, int days) {
		long msPerDay = 1000 * 60 * 60 * 24; // 一天的毫秒数
		long msTarget = target.getTime(); // 返回从一个特定的日期（1970。。）到现在经过的毫秒数。
		long msSum = msTarget + (msPerDay * days);
		Date result = new Date();
		result.setTime(msSum); // 根据毫秒设置日期
		return result;
	}

	public static Date beforeDays(Date target, int days) {
		long msPerDay = 1000 * 60 * 60 * 24; // 一天的毫秒数
		long msTarget = target.getTime(); // 返回从一个特定的日期（1970。。）到现在经过的毫秒数。
		long msSum = msTarget - (msPerDay * days);
		Date result = new Date();
		result.setTime(msSum); // 根据毫秒设置日期
		return result;
	}

	public static Date formatString(String time, String format) {
		try {
			SimpleDateFormat formater = new SimpleDateFormat(format);
			return formater.parse(time);
		} catch (Exception e) {
			return null;
		}
	}

	public static Date getFirstDateOfMonth(Date date) {
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(date);
		calendar.set(Calendar.DAY_OF_MONTH, 1);
		calendar.set(Calendar.HOUR_OF_DAY, 0);
		calendar.set(Calendar.MINUTE, 0);
		calendar.set(Calendar.SECOND, 0);
		return calendar.getTime();
	}

	public static Date getLastlyDateOfMonth(Date date) {
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(date);
		int month = calendar.get(Calendar.MONTH);
		calendar.set(Calendar.MONTH, month + 1);
		calendar.set(Calendar.DAY_OF_MONTH, 1);
		calendar.set(Calendar.HOUR_OF_DAY, 23);
		calendar.set(Calendar.MINUTE, 59);
		calendar.set(Calendar.SECOND, 59);
		calendar.add(Calendar.DAY_OF_MONTH, -1);
		return calendar.getTime();
	}

	public static Date getFirstDateOfNextMonth(Date date) {
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(date);
		int month = calendar.get(Calendar.MONTH);
		calendar.set(Calendar.MONTH, month + 1);
		calendar.set(Calendar.DAY_OF_MONTH, 1);
		calendar.set(Calendar.HOUR_OF_DAY, 0);
		calendar.set(Calendar.MINUTE, 0);
		calendar.set(Calendar.SECOND, 0);
		return calendar.getTime();

	}

	public static String getCurrentDayPath() {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy");
		Date now = new Date();
		String filePath = sdf.format(now) + "/";
		sdf = new SimpleDateFormat("MM");
		filePath += sdf.format(now) + "/";
		sdf = new SimpleDateFormat("dd");
		filePath += sdf.format(now) + "/";

		return filePath;
	}
}