一个处理Date与String的工具类

public class DateUtil {  
    private DateUtil(){  

    }  

    public static final String hhmmFormat="HH:mm";  
    public static final String MMddFormat="MM-dd";  
    public static final String yyyyFormat="yyyy";  
    public static final String yyyyChineseFormat="yyyy年";  
    public static final String yyyyMMddFormat="yyyy-MM-dd";
    public static final String fullFormat="yyyy-MM-dd HH:mm:ss";  
    public static final String MMddChineseFormat="MM月dd日";  
    public static final String yyyyMMddChineseFormat="yyyy年MM月dd日";  
    public static final String fullChineseFormat="yyyy年MM月dd日 HH时mm分ss秒";  
    public static final String [] WEEKS={"星期日","星期一","星期二","星期三","星期四","星期五","星期六"};  
    public static final String [] WEEKS_EN={"Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"};
    public static final String YMD_FORMAT = "yyyyMMdd";

    /** 
     * 得到指定时间的时间日期格式 
     * @param date 指定的时间 
     * @param format 时间日期格式 
     * @return 
*/  
    public static String getFormatDateTime(Date date,String format){
        DateFormat df=new SimpleDateFormat(format);  
        return df.format(date);  
    }  
    /** 
     * 得到指定时间的时间日期格式 
     * @param date 指定的时间 
     * @param format 时间日期格式 
     * @param land 语言类型 en=英文，zh_CN=中文
     * @return 
     */  

    public static String getFormatDateTime(Date date,String format,String land){  
        String time; 
        String week;
        DateFormat df=new SimpleDateFormat(format); 
        time = df.format(date);
        week = land.equals("zh_CN") ? WEEKS[getWeek(date)-1] : WEEKS_EN[getWeek(date)-1];
        time = time +"  "+week;
        return time;  
    }

    public static String formatDate(Date date, String format){
        DateFormat df=new SimpleDateFormat(format);
        return df.format(date);
    }

    public static String formatDateYmd(Date date){
        DateFormat df=new SimpleDateFormat("yyyyMMdd");
        return df.format(date);
    }

    public static String formatDateYmdHms(Date date){
        DateFormat df=new SimpleDateFormat("yyyyMMdd HH:mm:ss");
        return df.format(date);
    }

    public static Date stringToDateYmd(String dateString) {
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyyMMdd");
        Date date = null;
        try {
            date = simpleDateFormat.parse(dateString);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        String formattedTime = simpleDateFormat.format(date);

        date = java.sql.Date.valueOf(formattedTime);
        return date;
    }

    public static Date stringToDateYmdHms(String dateString) {
        Date date = null;
        try
        {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            date = sdf.parse(dateString);
        }
        catch (ParseException e)
        {
            System.out.println(e.getMessage());
        }
        return date;
    }

    public static Date  parseDateYmdHms(String dateString) {
        Date date = null;
        try
        {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd HH:mm:ss");
            date = sdf.parse(dateString);
        }
        catch (ParseException e)
        {
            throw new RuntimeException(e);
        }
        return date;
    }

    /** 
     * 判断是否是润年 
     * @param date 指定的时间 
     * @return true:是润年,false:不是润年 
*/  
    public static boolean isLeapYear(Date date) {  
       Calendar cal=Calendar.getInstance();  
       cal.setTime(date);  
       return isLeapYear(cal.get(Calendar.YEAR));  
    }  

    /** 
     * 判断是否是润年 
     * @param year 指定的年
     * @return true:是润年,false:不是润年 
     */
    public static boolean isLeapYear(int year) {  
       GregorianCalendar calendar = new GregorianCalendar();  
       return calendar.isLeapYear(year);  
    }  

    /** 
     * 判断指定的时间是否是今天 
     * @param date 指定的时间 
     * @return true:是今天,false:非今天 
*/  
    public static boolean isInToday(Date date){  
        boolean flag=false;  
        Date now=new Date();  
        String fullFormat=getFormatDateTime(now, DateUtil.yyyyMMddFormat);
        String beginString=fullFormat+" 00:00:00";  
        String endString=fullFormat+" 23:59:59";  
        DateFormat df=new SimpleDateFormat(DateUtil.fullFormat);
        try {  
            Date beginTime=df.parse(beginString);  
            Date endTime=df.parse(endString);  
            flag=date.before(endTime)&&date.after(beginTime);  
        } catch (ParseException e) {  
            e.printStackTrace();  
        }  
        return flag;  
    }  

    /** 
     * 判断两时间是否是同一天 
     * @param from 第一个时间点 
     * @param to 第二个时间点 
     * @return true:是同一天,false:非同一天 
*/  
    public static boolean isSameDay(Date from,Date to){  
        boolean isSameDay=false;  
        DateFormat df=new SimpleDateFormat(DateUtil.yyyyMMddFormat);
        String firstDate=df.format(from);  
        String secondDate=df.format(to);  
        isSameDay=firstDate.equals(secondDate);  
        return isSameDay;  
    }  

    /** 
     * 求出指定的时间那天是星期几 
     * @param date 指定的时间 
     * @return 星期X 
*/  
    public static String getWeekString(Date date){  
        return DateUtil.WEEKS[getWeek(date)-1];
    }  

    /** 
     * 求出指定时间那天是星期几 
     * @param date 指定的时间 
     * @return 1-7 
*/  
    public static int getWeek(Date date){  
        int week=0;  
        Calendar cal=Calendar.getInstance();  
        cal.setTime(date);  
        week=cal.get(Calendar.DAY_OF_WEEK);  
        return week;  
    }  

    /** 
     * 取得指定时间离现在是多少时间以前，如：3秒前,2小时前等 
     * 注意：此计算方法不是精确的 
     * @param date 已有的指定时间 
     * @return 时间段描述 
*/  
    public static String getAgoTimeString(Date date){  
        Date now=new Date();  
        Calendar cal=Calendar.getInstance();  
        cal.setTime(date);  
        Date agoTime=cal.getTime();  
        long mtime=now.getTime()-agoTime.getTime();  
        String str="";  
        long stime=mtime/1000;  
        long minute=60;  
        long hour=60*60;  
        long day=24*60*60;  
        long weeks=7*24*60*60;  
        long months=100*24*60*60;  
        if(stime<minute){  
            long time_value=stime;  
            if(time_value<=0){  
                time_value=1;  
            }  
            str=time_value+"秒前";  
        }else if(stime>=minute && stime<hour){  
            long time_value=stime/minute;  
            if(time_value<=0){  
                time_value=1;  
            }  
            str=time_value+"分前";  
        }else if(stime>=hour && stime<day){  
            long time_value=stime/hour;  
            if(time_value<=0){  
                time_value=1;  
            }  
            str=time_value+"小时前";  
        }else if(stime>=day&&stime<weeks){  
            long time_value=stime/day;  
            if(time_value<=0){  
                time_value=1;  
            }  
            str=time_value+"天前";  
        }else if(stime>=weeks&&stime<months){  
            DateFormat df=new SimpleDateFormat(DateUtil.MMddFormat);
            str=df.format(date);  
        }else{  
            DateFormat df=new SimpleDateFormat(DateUtil.yyyyMMddFormat);
            str=df.format(date);  
        }  
        return str;  
    }  

    /** 
     * 判断指定时间是否是周末 
     * @param date 指定的时间 
     * @return true:是周末,false:非周末 
*/  
    public static boolean isWeeks(Date date){  
        boolean isWeek=false;  
        isWeek=(getWeek(date)-1==0||getWeek(date)-1==6);  
        return isWeek;  
    }  

    /**
     * 获取当前日期
     * @return Date
     * */
    public static Date getToday(){
        String date = DateUtil.formatDate(new Date(), YMD_FORMAT);
        return DateUtil.stringToDateYmd(date);
    }

    /**
     * 获取当前日期
     * @return Date
     * */
    public static String getTodayStrYmd(){
        String date = DateUtil.formatDate(new Date(), YMD_FORMAT);
        return date;
    }

    /** 
     * 得到今天的最开始时间 
     * @return 今天的最开始时间 
*/  
    public static Date getTodayBeginTime(){  
        String beginString= DateUtil.yyyyMMddFormat+" 00:00:00";
        DateFormat df=new SimpleDateFormat(DateUtil.fullFormat);
        Date beginTime=new Date();  
        try {  
            beginTime=df.parse(beginString);  
        } catch (ParseException e) {  
            e.printStackTrace();  
        }  
        return beginTime;  
    }  

    /** 
     * 得到今天的最后结束时间 
     * @return 今天的最后时间 
*/  
    public static Date getTodayEndTime(){  
        String endString= DateUtil.yyyyMMddFormat+" 23:59:59";
        DateFormat df=new SimpleDateFormat(DateUtil.fullFormat);
        Date endTime=new Date();  
        try {  
            endTime=df.parse(endString);  
        } catch (ParseException e) {  
            e.printStackTrace();  
        }  
        return endTime;  
    }  

    /** 
     * 取得本周的开始时间 
     * @return 本周的开始时间 
*/  
    public static Date getThisWeekBeginTime(){  
        Date beginTime=null;  
        Calendar cal=Calendar.getInstance();  
        int week=getWeek(cal.getTime());  
        week=week-1;  
        int days=0;  
        if(week==0){  
            days=6;  
        }else{  
            days=week-1;  
        }  
        cal.add(Calendar.DAY_OF_MONTH, -days);  
        beginTime=cal.getTime();  
        return beginTime;  
    }  

    /** 
     * 取得本周的开始日期 
     * @param format 时间的格式 
     * @return 指定格式的本周最开始时间 
*/  
    public static String getThisWeekBeginTimeString(String format){  
        DateFormat df=new SimpleDateFormat(format);  
        return df.format(getThisWeekBeginTime());  
    }  

    /** 
     * 取得本周的结束时间 
     * @return 本周的结束时间 
*/  
    public static Date getThisWeekEndTime(){  
        Date endTime=null;  
        Calendar cal=Calendar.getInstance();  
        int week=getWeek(cal.getTime());  
        week=week-1;  
        int days=0;  
        if(week!=0){  
            days=7-week;  
        }  
        cal.add(Calendar.DAY_OF_MONTH, days);  
        endTime=cal.getTime();  
        return endTime;  
    }  

    /** 
     * 取得本周的结束日期 
     * @param format 时间的格式 
     * @return 指定格式的本周结束时间 
*/  
    public static String getThisWeekEndTimeString(String format){  
        DateFormat df=new SimpleDateFormat(format);  
        return df.format(getThisWeekEndTime());  
    }  

    /** 
     * 取得两时间相差的天数 
     * @param from 第一个时间 
     * @param to 第二个时间 
     * @return 相差的天数 
*/  
    public static long getBetweenDays(Date from, Date to){  
        long days=0;  
        long dayTime=24*60*60*1000;  
        long fromTime=from.getTime();  
        long toTime=to.getTime();  
        long times=Math.abs(fromTime-toTime);  
        days=times/dayTime;  
        return days;  
    }  

    /** 
     * 取得两时间相差的小时数 
     * @param from 第一个时间 
     * @param to 第二个时间 
     * @return 相差的小时数 
*/  
    public static long getBetweenHours(Date from,Date to){  
        long hours=0;  
        long hourTime=60*60*1000;  
        long fromTime=from.getTime();  
        long toTime=to.getTime();  
        long times=Math.abs(fromTime-toTime);  
        hours=times/hourTime;  
        return hours;  
    }  

    /** 
     * 取得在指定时间上加减days天后的时间 
     * @param date 指定的时间 
     * @param days 天数,正为加，负为减 
     * @return 在指定时间上加减days天后的时间 
*/  
    public static Date addDays(Date date,int days){  
        Date time=null;  
        Calendar cal=Calendar.getInstance();  
        cal.add(Calendar.DAY_OF_MONTH, days);  
        time=cal.getTime();  
        return time;  
    }  

    /** 
     * 取得在指定时间上加减months月后的时间 
     * @param date 指定时间 
     * @param months 月数，正为加，负为减 
     * @return 在指定时间上加减months月后的时间 
*/  
    public static Date addMonths(Date date,int months){  
        Date time=null;  
        Calendar cal=Calendar.getInstance();  
        cal.add(Calendar.MONTH, months);  
        time=cal.getTime();  
        return time;  
    }  

    /** 
     * 取得在指定时间上加减years年后的时间 
     * @param date 指定时间 
     * @param years 年数，正为加，负为减 
     * @return 在指定时间上加减years年后的时间 
*/  
    public static Date addYears(Date date,int years){  
        Date time=null;  
        Calendar cal=Calendar.getInstance();  
        cal.add(Calendar.YEAR, years);  
        time=cal.getTime();  
        return time;  
    }

    /**
     * @param args 
*/  
    public static void main(String[] args) {  

        System.out.println(getFormatDateTime(new Date(), DateUtil.yyyyMMddFormat,"en"));

       /* System.out.println(getFormatDateTime(new Date(),DateUtil.fullChineseFormat));  
        System.out.println(isLeapYear(new Date()));  
        Calendar cal=Calendar.getInstance();  
        System.out.println(isInToday(cal.getTime()));  
        Calendar cal2=Calendar.getInstance();  
        cal2.set(2011, 06, 05);  
        System.out.println(isSameDay(cal.getTime(),cal2.getTime()));  
        System.out.println(WEEKS[getWeek(new Date())]);  //星期几
        DateFormat df=new SimpleDateFormat(DateUtil.fullFormat);  
        String fullString="2011-06-03 22:37:20";  
        try {  
            Date fulldate=df.parse(fullString);  
            System.out.println(getBetweenDays(fulldate,cal.getTime()));  
            System.out.println("ago:"+getAgoTimeString(fulldate));  
            System.out.println(isWeeks(fulldate));  
        } catch (ParseException e) {  
            e.printStackTrace();  
        }  

        System.out.println(getThisWeekBeginTimeString(DateUtil.yyyyMMddChineseFormat));  
        System.out.println(getThisWeekEndTimeString(DateUtil.yyyyMMddChineseFormat));  
        System.out.println(addDays(new Date(),3));  
        System.out.println(addDays(new Date(),-3));  
        System.out.println(addMonths(new Date(),2));  
        System.out.println(addMonths(new Date(),-2));  
        System.out.println(addYears(new Date(),1));  
        System.out.println(addYears(new Date(),-1));  
          */
    }