Java DateUtil，日期整理

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

/** 
 * 说明：日期处理
 * @version
 */
public class DateUtil {
    
    private final static SimpleDateFormat sdfYear = new SimpleDateFormat("yyyy");
    private final static SimpleDateFormat sdfDay = new SimpleDateFormat("yyyy-MM-dd");
    private final static SimpleDateFormat sdfDays = new SimpleDateFormat("yyyyMMdd");
    private final static SimpleDateFormat sdfTime = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    private final static SimpleDateFormat sdfTimes = new SimpleDateFormat("yyyyMMddHHmmss");

    /**
     * 获取YYYY格式
     * @return
     */
    public static String getSdfTimes() {
        return sdfTimes.format(new Date());
    }
    
    /**
     * 获取YYYY格式
     * @return
     */
    public static String getYear() {
        return sdfYear.format(new Date());
    }

    /**
     * 获取YYYY-MM-DD格式
     * @return
     */
    public static String getDay() {
        return sdfDay.format(new Date());
    }
    
    /**
     * 获取YYYYMMDD格式
     * @return
     */
    public static String getDays(){
        return sdfDays.format(new Date());
    }

    /**
     * 获取YYYY-MM-DD HH:mm:ss格式
     * @return
     */
    public static String getTime() {
        return sdfTime.format(new Date());
    }

    /**
    * @Title: compareDate
    * @Description: TODO(日期比较，如果s>=e 返回true 否则返回false)
    * @param s
    * @param e
    * @return boolean  
    * @throws
    * @author fh
     */
    public static boolean compareDate(String s, String e) {
        if(fomatDate(s)==null||fomatDate(e)==null){
            return false;
        }
        return fomatDate(s).getTime() >=fomatDate(e).getTime();
    }

    /**
     * 格式化日期
     * @return
     */
    public static Date fomatDate(String date) {
        DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd");
        try {
            return fmt.parse(date);
        } catch (ParseException e) {
            e.printStackTrace();
            return null;
        }
    }

    /**
     * 校验日期是否合法
     * @return
     */
    public static boolean isValidDate(String s) {
        DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd");
        try {
            fmt.parse(s);
            return true;
        } catch (Exception e) {
            // 如果throw java.text.ParseException或者NullPointerException，就说明格式不对
            return false;
        }
    }
    
    /**
     * @param startTime
     * @param endTime
     * @return
     */
    public static int getDiffYear(String startTime,String endTime) {
        DateFormat fmt = new SimpleDateFormat("yyyy-MM-dd");
        try {
            //long aa=0;
            int years=(int) (((fmt.parse(endTime).getTime()-fmt.parse(startTime).getTime())/ (1000 * 60 * 60 * 24))/365);
            return years;
        } catch (Exception e) {
            // 如果throw java.text.ParseException或者NullPointerException，就说明格式不对
            return 0;
        }
    }
     
    /**
     * <li>功能描述：时间相减得到天数
     * @param beginDateStr
     * @param endDateStr
     * @return
     * long 
     * @author Administrator
     */
    public static long getDaySub(String beginDateStr,String endDateStr){
        long day=0;
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
        Date beginDate = null;
        Date endDate = null;
        
            try {
                beginDate = format.parse(beginDateStr);
                endDate= format.parse(endDateStr);
            } catch (ParseException e) {
                e.printStackTrace();
            }
            day=(endDate.getTime()-beginDate.getTime())/(24*60*60*1000);
            //System.out.println("相隔的天数="+day);
      
        return day;
    }
    
    /**
     * 得到n天之后的日期
     * @param days
     * @return
     */
    public static String getAfterDayDate(String days) {
        int daysInt = Integer.parseInt(days);
        
        Calendar canlendar = Calendar.getInstance(); // java.util包
        canlendar.add(Calendar.DATE, daysInt); // 日期减 如果不够减会将月变动
        Date date = canlendar.getTime();
        
        SimpleDateFormat sdfd = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String dateStr = sdfd.format(date);
        
        return dateStr;
    }
    
    /**
     * 得到n天之后是周几
     * @param days
     * @return
     */
    public static String getAfterDayWeek(String days) {
        int daysInt = Integer.parseInt(days);
        Calendar canlendar = Calendar.getInstance(); // java.util包
        canlendar.add(Calendar.DATE, daysInt); // 日期减 如果不够减会将月变动
        Date date = canlendar.getTime();
        SimpleDateFormat sdf = new SimpleDateFormat("E");
        String dateStr = sdf.format(date);
        return dateStr;
    }
    
    public static void main(String[] args) {
        System.out.println(getDays());
        System.out.println(getAfterDayWeek("3"));
    }

}