Java对时间(周)的处理 方法整理

/**
     * 增加天数,减传负值
     * @param format
     * @param day
     * @return
     */
    public static String getDateBeforeForma(String format, int day){
    	DateFormat dateFormat = new SimpleDateFormat(format);
    	Calendar now = Calendar.getInstance();      
    	now.add(Calendar.DATE, day);//增加一天 ,减传负值       
    	Date date=now.getTime();        
    	return dateFormat.format(date);
    }
    /**
     * 获得本周第一天(周一)的日期 
     * @return
     */
    public static String getWeekDay()
    {
    	Calendar cal =Calendar.getInstance();
        SimpleDateFormat df = new SimpleDateFormat("yyyy/MM/dd");
        cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY); //获取本周一的日期
        String time = df.format(cal.getTime());
	    return time;
    }

    /**
     * 获得上周时间
     * @return
     */
    public static String getLastWeek() {
    	SimpleDateFormat df = new SimpleDateFormat("yyyy/MM/dd");
    	Calendar date = Calendar.getInstance(Locale.CHINA);
        date.setFirstDayOfWeek(Calendar.MONDAY);//将每周第一天设为星期一，默认是星期天
        date.add(Calendar.WEEK_OF_MONTH,-1);//周数减一，即上周
        date.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);//日子设为星期一
        String time = df.format(date.getTime());

        Calendar date2 = Calendar.getInstance(Locale.CHINA);
        date2.setFirstDayOfWeek(Calendar.MONDAY);//将每周第一天设为星期一，默认是星期天
        date2.add(Calendar.WEEK_OF_MONTH,-1);//周数减一，即上周
        date2.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);//日子设为星期天
        String time2 = df.format(date2.getTime());

        return time + "-" + time2;
	}

    /** 
     * 获取某一时间段特定星期几的日期 
     * @param dateFrom 开始时间 
     * @param dateEnd 结束时间 
     * @param weekDays 星期 
     * @return 返回时间数组 
     */  
    public static String[] getDates(String dateFrom, String dateEnd, String weekDays) {  
        long time = 1l;  
        long perDayMilSec = 24 * 60 * 60 * 1000;  
        List<String> dateList = new ArrayList<String>();  
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");  
        //需要查询的星期系数  
        String strWeekNumber = weekForNum(weekDays);  
        try {  
            dateFrom = sdf.format(sdf.parse(dateFrom).getTime() - perDayMilSec);  
            while (true) {  
                    time = sdf.parse(dateFrom).getTime();  
                    time = time + perDayMilSec;  
                    Date date = new Date(time);  
                    dateFrom = sdf.format(date);  
                    if (dateFrom.compareTo(dateEnd) <= 0) {  
                        //查询的某一时间的星期系数  
                        Integer weekDay = dayForWeek(date);                      
                        //判断当期日期的星期系数是否是需要查询的  
                        if (strWeekNumber.indexOf(weekDay.toString())!=-1) {  
                            dateList.add(dateFrom);  
                        }  
                    } else {  
                        break;  
                    }  
            }  
        } catch (ParseException e1) {  
            e1.printStackTrace();  
        }  
        String[] dateArray = new String[dateList.size()];  
        dateList.toArray(dateArray);  
        return dateArray;  
    }  

    //等到当期时间的周系数。星期日：1，星期一：2，星期二：3，星期三：4，星期四：5，星期五：6，星期六：7  
    public static Integer dayForWeek(Date date) {  
        Calendar calendar = Calendar.getInstance();  
        calendar.setTime(date);  
        return calendar.get(Calendar.DAY_OF_WEEK);  
    }  

    /** 
     * 得到对应星期的系数  星期日：1，星期一：2，星期二：3，星期三：4，星期四：5，星期五：6，星期六：7 
     * @param weekDays 星期格式  星期一|星期二 
     */  
    public static String weekForNum(String weekDays){  
        //返回结果为组合的星期系数  
        String weekNumber = "";  
        //解析传入的星期  
        if(weekDays.indexOf("|")!=-1){//多个星期数  
            String []strWeeks = weekDays.split("\\|");  
            for(int i=0;i<strWeeks.length;i++){  
                weekNumber = weekNumber + "" + getWeekNum(strWeeks[i]).toString();  
            }  
        }else{//一个星期数  
            weekNumber = getWeekNum(weekDays).toString();  
        }  

        return weekNumber;  

    }  

    //将星期转换为对应的系数  星期日：1，星期一：2，星期二：3，星期三：4，星期四：5，星期五：6，星期六：7  
    public static Integer getWeekNum(String strWeek){  
        Integer number = 1;//默认为星期日  
        if("星期日".equals(strWeek)){  
            number = 1;  
        }else if("星期一".equals(strWeek)){  
            number = 2;  
        }else if("星期二".equals(strWeek)){  
            number = 3;  
        }else if("星期三".equals(strWeek)){  
            number = 4;  
        }else if("星期四".equals(strWeek)){  
            number = 5;  
        }else if("星期五".equals(strWeek)){  
            number = 6;  
        }else if("星期六".equals(strWeek)){  
            number = 7;  
        }else{  
            number = 1;  
        }  
        return number;  
    } 

    //根据年份和当年的第几周，获取这一周的日期
    public static String getDayOfWeek(int year, int weekindex) {
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy/MM/dd");
        Calendar c = Calendar.getInstance();
        c.setWeekDate(year, weekindex, 1);

        int dayOfWeek = c.get(Calendar.DAY_OF_WEEK) - 2;
        c.add(Calendar.DATE, -dayOfWeek); // 得到本周的第一天
        String begin = sdf.format(c.getTime());
        c.add(Calendar.DATE, 6); // 得到本周的最后一天
        String end = sdf.format(c.getTime());
        String range = begin + "-" + end;
        return range;
    }