java获得上下周及本周日期

    public static SimpleDateFormat getFormat(String format) {
        return new SimpleDateFormat(format);
    }

    /**
     * 获取上周周几的日期,默认一周从周一开始
     * 
     * @param dayOfWeek
     * @param weekOffset
     * @return
     */
    public static Date getDayOfWeek(int dayOfWeek, int weekOffset) {
        return getDayOfWeek(Calendar.MONDAY, dayOfWeek, weekOffset);
    }

    /**
     * 获取上(下)周周几的日期
     * 
     * @param firstDayOfWeek {@link Calendar} 值范围 <code>SUNDAY</code>,
     *                       <code>MONDAY</code>, <code>TUESDAY</code>,
     *                       <code>WEDNESDAY</code>, <code>THURSDAY</code>,
     *                       <code>FRIDAY</code>, and <code>SATURDAY</code>
     * @param dayOfWeek      {@link Calendar}
     * @param weekOffset     周偏移，上周为-1，本周为0，下周为1，以此类推
     * @return
     */
    public static Date getDayOfWeek(int firstDayOfWeek, int dayOfWeek, int weekOffset) {
        if (dayOfWeek > Calendar.SATURDAY || dayOfWeek < Calendar.SUNDAY) {
            return null;
        }
        if (firstDayOfWeek > Calendar.SATURDAY || firstDayOfWeek < Calendar.SUNDAY) {
            return null;
        }
        Calendar date = Calendar.getInstance(Locale.CHINA);
        date.setFirstDayOfWeek(firstDayOfWeek);
        // 周数减一，即上周
        date.add(Calendar.WEEK_OF_MONTH, weekOffset);
        // 日子设为周几
        date.set(Calendar.DAY_OF_WEEK, dayOfWeek);
        // 时分秒全部置0
        date.set(Calendar.HOUR_OF_DAY, 0);
        date.set(Calendar.MINUTE, 0);
        date.set(Calendar.SECOND, 0);
        date.set(Calendar.MILLISECOND, 0);
        return date.getTime();
    }

    public static void main(String[] args) {
        System.out.println(
                getFormat(DateTimeUtil.YEAR_MONTH_DATE_2).format(getDayOfWeek(Calendar.MONDAY, -1)));
        System.out.println(
                getFormat(DateTimeUtil.YEAR_MONTH_DATE_2).format(getDayOfWeek(Calendar.SUNDAY, -1)));
    }