Java常用日期处理工具函数类

/**
 * 常用日期处理工具类
 */
 public class dateUtils{

/**
	 * 格式化当前时间
	 * @param pattern
	 * @return
	 */
	public static String format(String pattern){
		SimpleDateFormat df = new SimpleDateFormat(pattern);
		return df.format(new Date());
	}
	
	/**
	 * 格式化指定时间
	 * @param date
	 * @param pattern
	 * @return
	 */
	public static String format(Date date, String pattern){
		SimpleDateFormat df = new SimpleDateFormat(pattern);
		return df.format(date);
	}
	
	
	/**
	 * 解释日期
	 * @param str
	 * @param pattern
	 * @return
	 * @throws Exception
	 */
	public static Date parse(String str, String pattern) throws Exception{
		SimpleDateFormat df = new SimpleDateFormat(pattern);
		Date date = df.parse(str);
		return date;
	}
	
	/**
	 * 得到当天开始日期
	 * @return
	 * @throws Exception
	 */
	public static Date getDate() throws Exception{
		return OspUtils.parse(OspUtils.format("yyyyMMdd"),"yyyyMMdd");
	}
	
	/**
	 * 在指定的日期增加天数
	 * @param initDate
	 * @param diff
	 * @return
	 */
	public static Date addDay2Date(Date initDate , int diff){
		Calendar cal = Calendar.getInstance();
		cal.setTime(initDate);
		cal.add(Calendar.DATE, diff);	
		return new Date(cal.getTimeInMillis());
	}
	
	/**
	 * 返回当天起始时间
	 * @return
	 */
	public static Date getCurrentDayStart() throws Exception{
		String start = format("yyyyMMdd")+"000000";
		return parse(start, yyyyMMddhhmmss);
		
	}
	
	/**
	 * 返回当天结束时间
	 * @return
	 */
	public static Date getCurrentDayend() throws Exception{
		String start = format("yyyyMMdd")+"235959";
		return parse(start, yyyyMMddhhmmss);
		
	}
	
	/**
	 * 判断日期是否是当天时间
	 * @param date
	 * @return
	 */
	public static boolean judgeDateIsCurrentDay(Date date){
		
		try {
			long time = date.getTime();
			long Daystart = getCurrentDayStart().getTime();
			long Dayend = getCurrentDayend().getTime();
			return Daystart<=time && time<=Dayend;
		} catch (Exception e) {
		}
		return false;
	}
	
	/**
	 * 比较日期字符串返回天数
	 * @param strBegin 格式：yyyy-MM-dd
	 * @param strEnd   格式：yyyy-MM-dd
	 * @return
	 * @throws Exception
	 */
	public static int getDifferDays(String strBegin,String strEnd) throws Exception {
		   
        java.util.Calendar calst = java.util.Calendar.getInstance();   
        java.util.Calendar caled = java.util.Calendar.getInstance();  
        
        calst.setTime(parse(strBegin.concat(" 00:00:00"), yyyyMMddhhmmss));   
        caled.setTime(parse(strEnd.concat(" 00:00:00"), yyyyMMddhhmmss));   
  
        //得到两个日期相差的天数   
        int days = ((int) (caled.getTime().getTime() / 1000) - (int) (calst   
                .getTime().getTime() / 1000)) / 3600 / 24;   
           
        return days;   
    
	}
	
	/**
	 * 比较日期返回天数
	 * @param strBegin
	 * @param strEnd
	 * @return
	 */
	public static final int getDifferDays(Date strBegin, Date strEnd) {   
        java.util.Calendar calst = java.util.Calendar.getInstance();   
        java.util.Calendar caled = java.util.Calendar.getInstance();   
        calst.setTime(strBegin);   
        caled.setTime(strEnd);   
        //设置时间为0时   
        calst.set(java.util.Calendar.HOUR_OF_DAY, 0);   
        calst.set(java.util.Calendar.MINUTE, 0);   
        calst.set(java.util.Calendar.SECOND, 0);   
        caled.set(java.util.Calendar.HOUR_OF_DAY, 0);   
        caled.set(java.util.Calendar.MINUTE, 0);   
        caled.set(java.util.Calendar.SECOND, 0);   
  
        //得到两个日期相差的天数   
        int days = ((int) (caled.getTime().getTime() / 1000) - (int) (calst   
                .getTime().getTime() / 1000)) / 3600 / 24;   
           
        return days;   
    }   

	
	public static final String DATE_PATTERN_YYYY_MM_DD = "yyyy-MM-dd";
	public static final String yyyyMMddhhmmss = "yyyyMMddhhmmss";

}