DATE 工具类

public class DateUtil
{
	//默认显示日期的格式
	public static final String DATAFORMAT_STR = "yyyy-MM-dd";
	
	//默认显示日期的格式
	public static final String YYYY_MM_DATAFORMAT_STR = "yyyy-MM";
	
	//默认显示日期时间的格式
	public static final String DATATIMEF_STR = "yyyy-MM-dd HH:mm:ss";
	
	//默认显示简体中文日期的格式
	public static final String ZHCN_DATAFORMAT_STR = "yyyy年MM月dd日";
	
	//默认显示简体中文日期时间的格式
	public static final String ZHCN_DATATIMEF_STR = "yyyy年MM月dd日HH时mm分ss秒";
	
	//默认显示简体中文日期时间的格式
	public static final String ZHCN_DATATIMEF_STR_4yMMddHHmm = "yyyy年MM月dd日HH时mm分";
	
	private static DateFormat dateFormat = null;
	
	private static DateFormat dateTimeFormat = null;
	
	private static DateFormat zhcnDateFormat = null;
	
	private static DateFormat zhcnDateTimeFormat = null;
	static
	{
		dateFormat = new SimpleDateFormat(DATAFORMAT_STR);
		dateTimeFormat = new SimpleDateFormat(DATATIMEF_STR);
		zhcnDateFormat = new SimpleDateFormat(ZHCN_DATAFORMAT_STR);
		zhcnDateTimeFormat = new SimpleDateFormat(ZHCN_DATATIMEF_STR);
	}
	
	private static DateFormat getDateFormat(String formatStr)
	{
		if (formatStr.equalsIgnoreCase(DATAFORMAT_STR))
		{
			return dateFormat;
		}
		else
			if (formatStr.equalsIgnoreCase(DATATIMEF_STR))
			{
				return dateTimeFormat;
			}
			else
				if (formatStr.equalsIgnoreCase(ZHCN_DATAFORMAT_STR))
				{
					return zhcnDateFormat;
				}
				else
					if (formatStr.equalsIgnoreCase(ZHCN_DATATIMEF_STR))
					{
						return zhcnDateTimeFormat;
					}
					else
					{
						return new SimpleDateFormat(formatStr);
					}
	}
	
	/**
	 * 按照默认显示日期时间的格式"yyyy-MM-dd HH:mm:ss"，转化dateTimeStr为Date类型
	 * dateTimeStr必须是"yyyy-MM-dd HH:mm:ss"的形式
	 * @param dateTimeStr
	 * @return
	 */
	public static Date getDate(String dateTimeStr)
	{
		return getDate(dateTimeStr, DATATIMEF_STR);
	}
	
	/**
	 * 按照默认formatStr的格式，转化dateTimeStr为Date类型
	 * dateTimeStr必须是formatStr的形式
	 * @param dateTimeStr
	 * @param formatStr
	 * @return
	 */
	public static Date getDate(String dateTimeStr, String formatStr)
	{
		try
		{
			if (dateTimeStr == null || dateTimeStr.equals(""))
			{
				return null;
			}
			DateFormat sdf = getDateFormat(formatStr);
			java.util.Date d = sdf.parse(dateTimeStr);
			return d;
		}
		catch (ParseException e)
		{
			throw new RuntimeException(e);
		}
	}
	
	/**
	 * 将YYYYMMDD转换成Date日期
	 * @param date
	 * @return
	 * @throws BusinessException
	 */
	public static Date transferDate(String date) throws Exception
	{
		if (date == null || date.length() < 1)
			return null;
		
		if (date.length() != 8)
			throw new Exception("日期格式错误");
		String con = "-";
		
		String yyyy = date.substring(0, 4);
		String mm = date.substring(4, 6);
		String dd = date.substring(6, 8);
		
		int month = Integer.parseInt(mm);
		int day = Integer.parseInt(dd);
		if (month < 1 || month > 12 || day < 1 || day > 31)
			throw new Exception("日期格式错误");
		
		String str = yyyy + con + mm + con + dd;
		return DateUtil.getDate(str, DateUtil.DATAFORMAT_STR);
	}
	
	/**
	 * 将YYYY－MM－DD日期转换成yyyymmdd格式字符串
	 * @param date
	 * @return
	 */
	public static String getYYYYMMDDDate(Date date)
	{
		if (date == null)
			return null;
		String yyyy = getYear(date) + "";
		String mm = getMonth(date) + "";
		String dd = getDay(date) + "";
		
		mm = StringUtil.rightAlign(mm, 2, "0");
		dd = StringUtil.rightAlign(dd, 2, "0");
		return yyyy + mm + dd;
	}
	
	/**
	 * 将YYYY－MM－DD日期转换成YYYYMMDDHHMMSS格式字符串
	 * @param date
	 * @return
	 */
	public static String getYYYYMMDDHHMMSSDate(Date date)
	{
		if (date == null)
			return null;
		String yyyy = getYear(date) + "";
		String mm = getMonth(date) + "";
		String dd = getDay(date) + "";
		String hh = getHour(date) + "";
		String min = getMin(date) + "";
		String ss = getSecond(date) + "";
		
		mm = StringUtil.rightAlign(mm, 2, "0");
		dd = StringUtil.rightAlign(dd, 2, "0");
		hh = StringUtil.rightAlign(hh, 2, "0");
		min = StringUtil.rightAlign(min, 2, "0");
		ss = StringUtil.rightAlign(ss, 2, "0");
		
		return yyyy + mm + dd + hh + min + ss;
	}
	
	/**
	 * 将YYYY－MM－DD日期转换成yyyymmdd格式字符串
	 * @param date
	 * @return
	 */
	public static String getYYYYMMDDDate(String date)
	{
		return getYYYYMMDDDate(getDate(date, DATAFORMAT_STR));
	}
	
	/**
	 * 将Date转换成字符串“yyyy-mm-dd hh:mm:ss”的字符串
	 * @param date
	 * @return
	 */
	public static String dateToDateString(Date date)
	{
		return dateToDateString(date, DATATIMEF_STR);
	}
	
	/**
	 * 将Date转换成formatStr格式的字符串
	 * @param date
	 * @param formatStr
	 * @return
	 */
	public static String dateToDateString(Date date, String formatStr)
	{
		DateFormat df = getDateFormat(formatStr);
		return df.format(date);
	}
	
	/**
	 * 返回一个yyyy-MM-dd HH:mm:ss 形式的日期时间字符串中的HH:mm:ss
	 * @param dateTime
	 * @return
	 */
	public static String getTimeString(String dateTime)
	{
		return getTimeString(dateTime, DATATIMEF_STR);
	}
	
	/**
	 * 返回一个formatStr格式的日期时间字符串中的HH:mm:ss
	 * @param dateTime
	 * @param formatStr
	 * @return
	 */
	public static String getTimeString(String dateTime, String formatStr)
	{
		Date d = getDate(dateTime, formatStr);
		String s = dateToDateString(d);
		return s.substring(DATATIMEF_STR.indexOf('H'));
	}
	
	/**
	 * 获取当前日期yyyy-MM-dd的形式
	 * @return
	 */
	public static String getCurDate()
	{
		//return dateToDateString(new Date(),DATAFORMAT_STR);
		return dateToDateString(Calendar.getInstance().getTime(), DATAFORMAT_STR);
	}
	
	/**
	 * 获取当前日期yyyy年MM月dd日的形式
	 * @return
	 */
	public static String getCurZhCNDate()
	{
		return dateToDateString(new Date(), ZHCN_DATAFORMAT_STR);
	}
	
	/**
	 * 获取当前日期时间yyyy-MM-dd HH:mm:ss的形式
	 * @return
	 */
	public static String getCurDateTime()
	{
		return dateToDateString(new Date(), DATATIMEF_STR);
	}
	
	/**
	 * 获取当前日期时间yyyy年MM月dd日HH时mm分ss秒的形式
	 * @return
	 */
	public static String getCurZhCNDateTime()
	{
		return dateToDateString(new Date(), ZHCN_DATATIMEF_STR);
	}
	
	/**
	 * 获取日期d的days天后的一个Date
	 * @param d
	 * @param days
	 * @return
	 */
	public static Date getInternalDateByDay(Date d, int days)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		now.add(Calendar.DATE, days);
		return now.getTime();
	}
	
	public static Date getInternalDateByMon(Date d, int months)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		now.add(Calendar.MONTH, months);
		return now.getTime();
	}
	
	public static Date getInternalDateByYear(Date d, int years)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		now.add(Calendar.YEAR, years);
		return now.getTime();
	}
	
	public static Date getInternalDateBySec(Date d, int sec)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		now.add(Calendar.SECOND, sec);
		return now.getTime();
	}
	
	public static Date getInternalDateByMin(Date d, int min)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		now.add(Calendar.MINUTE, min);
		return now.getTime();
	}
	
	public static Date getInternalDateByHour(Date d, int hours)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		now.add(Calendar.HOUR_OF_DAY, hours);
		return now.getTime();
	}
	
	/**
	 * 根据一个日期字符串，返回日期格式，目前支持4种
	 * 如果都不是，则返回null
	 * @param DateString
	 * @return
	 */
	public static String getFormateStr(String DateString)
	{
		String patternStr1 = "[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}"; //"yyyy-MM-dd"
		String patternStr2 = "[0-9]{4}-[0-9]{1,2}-[0-9]{1,2}\\s[0-9]{1,2}:[0-9]{1,2}:[0-9]{1,2}"; //"yyyy-MM-dd HH:mm:ss";
		String patternStr3 = "[0-9]{4}年[0-9]{1,2}月[0-9]{1,2}日";//"yyyy年MM月dd日"
		String patternStr4 = "[0-9]{4}年[0-9]{1,2}月[0-9]{1,2}日[0-9]{1,2}时[0-9]{1,2}分[0-9]{1,2}秒";//"yyyy年MM月dd日HH时mm分ss秒"
		
		Pattern p = Pattern.compile(patternStr1);
		Matcher m = p.matcher(DateString);
		boolean b = m.matches();
		if (b)
			return DATAFORMAT_STR;
		p = Pattern.compile(patternStr2);
		m = p.matcher(DateString);
		b = m.matches();
		if (b)
			return DATATIMEF_STR;
		
		p = Pattern.compile(patternStr3);
		m = p.matcher(DateString);
		b = m.matches();
		if (b)
			return ZHCN_DATAFORMAT_STR;
		
		p = Pattern.compile(patternStr4);
		m = p.matcher(DateString);
		b = m.matches();
		if (b)
			return ZHCN_DATATIMEF_STR;
		return null;
	}
	
	/**
	 * 将一个"yyyy-MM-dd HH:mm:ss"字符串，转换成"yyyy年MM月dd日HH时mm分ss秒"的字符串
	 * @param dateStr
	 * @return
	 */
	public static String getZhCNDateTime(String dateStr)
	{
		Date d = getDate(dateStr);
		return dateToDateString(d, ZHCN_DATATIMEF_STR);
	}
	
	/**
	 * 将一个"yyyy-MM-dd"字符串，转换成"yyyy年MM月dd日"的字符串
	 * @param dateStr
	 * @return
	 */
	public static String getZhCNDate(String dateStr)
	{
		Date d = getDate(dateStr, DATAFORMAT_STR);
		return dateToDateString(d, ZHCN_DATAFORMAT_STR);
	}
	
	/**
	 * 将dateStr从fmtFrom转换到fmtTo的格式
	 * @param dateStr
	 * @param fmtFrom
	 * @param fmtTo
	 * @return
	 */
	public static String getDateStr(String dateStr, String fmtFrom, String fmtTo)
	{
		Date d = getDate(dateStr, fmtFrom);
		return dateToDateString(d, fmtTo);
	}
	
	/**
	 * 比较两个"yyyy-MM-dd HH:mm:ss"格式的日期，之间相差多少毫秒,time2-time1
	 * @param time1
	 * @param time2
	 * @return
	 */
	public static long compareDateStr(String time1, String time2)
	{
		Date d1 = getDate(time1);
		Date d2 = getDate(time2);
		return d2.getTime() - d1.getTime();
	}
	
	/**
	 * 将小时数换算成返回以毫秒为单位的时间
	 * @param hours
	 * @return
	 */
	public static long getMicroSec(BigDecimal hours)
	{
		BigDecimal bd;
		bd = hours.multiply(new BigDecimal(3600 * 1000));
		return bd.longValue();
	}
	
	/**
	 * 获取Date中的分钟
	 * @param d
	 * @return
	 */
	public static int getMin(Date d)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		return now.get(Calendar.MINUTE);
	}
	
	/**
	 * 获取Date中的小时(24小时)
	 * @param d
	 * @return
	 */
	public static int getHour(Date d)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		return now.get(Calendar.HOUR_OF_DAY);
	}
	
	/**
	 * 获取Date中的秒
	 * @param d
	 * @return
	 */
	public static int getSecond(Date d)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		return now.get(Calendar.SECOND);
	}
	
	/**
	 * 获取xxxx-xx-xx的日
	 * @param d
	 * @return
	 */
	public static int getDay(Date d)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		return now.get(Calendar.DAY_OF_MONTH);
	}
	
	/**
	 * 获取月份，1-12月
	 * @param d
	 * @return
	 */
	public static int getMonth(Date d)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		return now.get(Calendar.MONTH) + 1;
	}
	
	/**
	 * 获取19xx,20xx形式的年
	 * @param d
	 * @return
	 */
	public static int getYear(Date d)
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		now.setTime(d);
		return now.get(Calendar.YEAR);
	}
	
	/**
	 * 得到d的上个月的年份+月份,如200505
	 * @return
	 */
	public static String getYearMonthOfLastMon(Date d)
	{
		Date newdate = getInternalDateByMon(d, -1);
		String year = String.valueOf(getYear(newdate));
		String month = String.valueOf(getMonth(newdate));
		return year + month;
	}
	
	/**
	 * 得到当前日期的年和月如200509
	 * @return String
	 */
	public static String getCurYearMonth()
	{
		Calendar now = Calendar.getInstance(TimeZone.getDefault());
		String DATE_FORMAT = "yyyyMM";
		java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat(DATE_FORMAT);
		sdf.setTimeZone(TimeZone.getDefault());
		return (sdf.format(now.getTime()));
	}
	
	public static Date getNextMonth(String year, String month)
	{
		String datestr = year + "-" + month + "-01";
		Date date = getDate(datestr, DATAFORMAT_STR);
		return getInternalDateByMon(date, 1);
	}
	
	public static Date getLastMonth(String year, String month)
	{
		String datestr = year + "-" + month + "-01";
		Date date = getDate(datestr, DATAFORMAT_STR);
		return getInternalDateByMon(date, -1);
	}
	
	/**
	 * 得到日期d，按照页面日期控件格式，如"2001-3-16"
	 * @param d
	 * @return
	 */
	public static String getSingleNumDate(Date d)
	{
		return dateToDateString(d, DATAFORMAT_STR);
	}
	
	/**
	 * 得到d半年前的日期,"yyyy-MM-dd"
	 * @param d
	 * @return
	 */
	public static String getHalfYearBeforeStr(Date d)
	{
		return dateToDateString(getInternalDateByMon(d, -6), DATAFORMAT_STR);
	}
	
	/**
	 * 得到当前日期D的月底的前/后若干天的时间,<0表示之前，>0表示之后
	 * @param d
	 * @param days
	 * @return
	 */
	public static String getInternalDateByLastDay(Date d, int days)
	{
		
		return dateToDateString(getInternalDateByDay(d, days), DATAFORMAT_STR);
	}
	
	/**
	 * 日期中的年月日相加
	 *  @param field int  需要加的字段  年 月 日
	 * @param amount int 加多少
	 * @return String
	 */
	public static String addDate(int field, int amount)
	{
		int temp = 0;
		if (field == 1)
		{
			temp = Calendar.YEAR;
		}
		if (field == 2)
		{
			temp = Calendar.MONTH;
		}
		if (field == 3)
		{
			temp = Calendar.DATE;
		}
		
		String Time = "";
		try
		{
			SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
			Calendar cal = Calendar.getInstance(TimeZone.getDefault());
			cal.add(temp, amount);
			Time = sdf.format(cal.getTime());
			return Time;
		}
		catch (Exception e)
		{
			e.printStackTrace();
			return null;
		}
		
	}
	
	/**
	 * 获得系统当前月份的天数
	 * @return
	 */
	public static int getCurentMonthDay()
	{
		Date date = Calendar.getInstance().getTime();
		return getMonthDay(date);
	}
	
	/**
	 * 获得指定日期月份的天数
	 * @return
	 */
	public static int getMonthDay(Date date)
	{
		Calendar c = Calendar.getInstance();
		c.setTime(date);
		return c.getActualMaximum(Calendar.DAY_OF_MONTH);
		
	}
	
	/**
	 * 获得指定日期月份的天数  yyyy-mm-dd
	 * @return
	 */
	public static int getMonthDay(String date)
	{
		Date strDate = getDate(date, DATAFORMAT_STR);
		return getMonthDay(strDate);
		
	}
	
	public static String getStringDate(Calendar cal)
	{
		
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
		return format.format(cal.getTime());
	}
	
	/**
	 * @param args
	 */
	public static void main(String[] args)
	{
		//		//System.out.print(DateUtil.getDate("04:04:04","HH:mm:ss"));
		//		System.out.print("\n"+DateUtil.getCurZhCNDateTime());
		//		System.out.print("\n"+getFormateStr(DateUtil.getCurDate()));
		//		System.out.print("\n"+compareDateStr("1900-1-1 1:1:2","1900-1-1 1:1:3"));
		//		System.out.print("\n"+getDay(new Date()));
		//		System.out.print("\n"+getMonth(new Date()));
		//		System.out.print("\n"+getYear(new Date()));
		//		System.out.print("\n"+getMin(new Date()));
		////		System.out.print("\n"+new Date().getSeconds());
		/*Date d1 = new Date(2007,11,30);
		Date d2 = new Date(2007,12,1);
		if(d2.compareTo(d1)>0){
		    System.out.println("d2大于d1");
		}else{
		    System.out.println("d2小于d1");
		}*/

		System.out.println(addDate(1, 1));
		System.out.println(addDate(2, 1));
		System.out.println(addDate(3, 1));
		
		System.out.println(getYYYYMMDDHHMMSSDate(new Date()));
		
		System.out.println(getCurentMonthDay());
		
	}
	
}

谢谢楼主，这样类太好了，很实用

谢谢，准备用。
函数很长，好像部分函数可以重构一下
比如：
getYYYYMMDDDate(Date date) 和getYYYYMMDDHHMMSSDate(Date date)

完全可以用一个函数实现
另外这两个函数体里的实现，似乎啰嗦了些，直接用类似：

 String pattern = "yyyyMMddHHmmss";
		SimpleDateFormat sdf= new SimpleDateFormat(pattern);
		
		String sDateStr = sdf.format(date);
		return sDateStr;

即可。


pattern 可以改成静态常量，作为参数传入。