Java 日期工具类

        项目中的订单统计需求，分别是按日，周，月，年统计订单数量及订单总额。其中，遇到了各种时间的获取，下面总结了一些较全的Java获取不同时间以及不同时间格式的相互转换方法。

    /**
     * 获取当前年
     * @return
     */
    public static Integer getNowYear() {
        Date date = new Date();
        GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();
        gc.setTime(date);
        return Integer.valueOf(gc.get(1));
    }

    /**
     * 获取一年的开始时间
     * @return
     */
    public static Date getBeginDayOfYear() {
        Calendar calendar = Calendar.getInstance();
        calendar.set(Calendar.YEAR, getNowYear());
        calendar.set(Calendar.MONTH, Calendar.JANUARY);
        calendar.set(Calendar.DATE, 1);
        return getDayStartTime(calendar.getTime());
    }

    /**
     * 获取一天的开始时间
     * @param d
     * @return
     */
    public static Timestamp getDayStartTime(Date d) {
        Calendar calendar = Calendar.getInstance();
        if (null != d)
            calendar.setTime(d);
        calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
        calendar.set(Calendar.MILLISECOND, 0);
        return new Timestamp(calendar.getTimeInMillis());
    }

    /**
     * 获得当天0点时间
     * @return
     */
    public static Date getTimesmorning() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.HOUR_OF_DAY, 0);
        cal.set(Calendar.SECOND, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.MILLISECOND, 0);
        return cal.getTime();

    }

    /**
     * 获得昨天的0点时间
     * @return
     */
    public static Date getYesterdaymorning() {
        Calendar cal = Calendar.getInstance();
        cal.setTimeInMillis(getTimesmorning().getTime() - 3600 * 24 * 1000);
        return cal.getTime();
    }

     /**
     * 获得当天24点时间
     * @return
     */
    public static Date getTimesnight() {
        Calendar cal = Calendar.getInstance();
        cal.set(Calendar.HOUR_OF_DAY, 24);
        cal.set(Calendar.SECOND, 0);
        cal.set(Calendar.MINUTE, 0);
        cal.set(Calendar.MILLISECOND, 0);
        return cal.getTime();
    }

    /**
     * 获得本周一0点时间
     * @return
     */
    public static Date getTimesWeekmorning() {
        Calendar cal = Calendar.getInstance();
        cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONDAY), cal.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
        cal.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);
        return cal.getTime();
    }

    /**
     * 获得本周日24点时间
     * @return
     */
    public static Date getTimesWeeknight() {
        Calendar cal = Calendar.getInstance();
        cal.setTime(getTimesWeekmorning());
        cal.add(Calendar.DAY_OF_WEEK, 7);
        return cal.getTime();
    }

    /**
     * 获得本月第一天0点时间
     * @return
     */
    public static Date getTimesMonthmorning() {
        Calendar cal = Calendar.getInstance();
        cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONDAY), cal.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
        cal.set(Calendar.DAY_OF_MONTH, cal.getActualMinimum(Calendar.DAY_OF_MONTH));
        return cal.getTime();
    }

    /**
     * 获得本月最后一天24点时间
     * @return
     */
    public static Date getTimesMonthnight() {
        Calendar cal = Calendar.getInstance();
        cal.set(cal.get(Calendar.YEAR), cal.get(Calendar.MONDAY), cal.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
        cal.set(Calendar.DAY_OF_MONTH, cal.getActualMaximum(Calendar.DAY_OF_MONTH));
        cal.set(Calendar.HOUR_OF_DAY, 24);
        return cal.getTime();
    }

    /** 默认的格式: yyyy-MM-dd HH:mm:ss */
    public static final String FMT_DEFAULT = "yyyy-MM-dd HH:mm:ss";

    /**
     * 日期格式转为字符串格式[格式：yyyy-MM-dd HH:mm:ss]
     * @param date：传入的日期
     * @return    ：String
     */
    public static String parseString(Date date) {
        SimpleDateFormat simpDateFormat = new SimpleDateFormat(FMT_DEFAULT);
        return simpDateFormat.format(date);
    }

    /**
     * 字符串格式转日期
     * @param str：传入的字符串
     * @return   ：Date
     */
    public static Date parseDate(String str) {
        SimpleDateFormat simpDateFormat = new SimpleDateFormat(FMT_DEFAULT);
        try {
            return simpDateFormat.parse(str);
        } catch (ParseException e) {
            throw new RuntimeException("日期格式不正确 value[" + str + "]");
        }
    }