Date與String互相轉換及日期的大小比較

private static final String PATTERN = "yyyy-MM-dd HH:mm:ss";

/**
 * String轉Date
 *
 * @param str
 * @return
 */
public static Date strToDate(String str) {
    if (StringUtils.isEmpty(str)) {
        return null;
    }

    SimpleDateFormat sdf = new SimpleDateFormat(PATTERN);

    try {
        return sdf.parse(str);
    } catch (ParseException e) {
        e.printStackTrace();
    }

    return null;
}

/**
 * Date轉String
 *
 * @param date
 * @return
 */
public static String dateToStr(Date date) {
    SimpleDateFormat sdf = new SimpleDateFormat(PATTERN);
    String time = sdf.format(date);
    return time;
}

/**
 * 通過Date自帶方法before()和after()比較時間大小
 * 通過Date的compareTo()方法比較時間大小
 *
 * @param beginTime
 * @param endTime
 * @return
 */
public static void compare(String beginTime, String endTime) {
    Date beginDate = strToDate(beginTime);
    Date endDate = strToDate(endTime);
    if (beginDate != null && endDate != null) {
        System.out.println(beginDate.before(endDate));
        System.out.println(beginDate.after(endDate));
        System.out.println(beginDate.compareTo(endDate));
    }
}

/**
 * 通過String的compareTo()方法比較時間大小
 * 返回正值是代表左側日期大於參數日期，反之亦然，日期格式必須一致
 *
 * @param beginTime
 * @param endTime
 * @return
 */
public static void compare2(String beginTime, String endTime) {
    Integer i = beginTime.compareTo(endTime);
    System.out.println(i);
}

/**
 * 轉成Date格式換成秒數比較秒數大小，通過getTime()方法
 *
 * @param beginTime
 * @param endTime
 * @return
 */
public static void compare3(String beginTime, String endTime) {
    Date beginDate = strToDate(beginTime);
    Date endDate = strToDate(endTime);
    long begin;
    long end;
    if (beginDate != null && endDate != null) {
        begin = beginDate.getTime();
        end = endDate.getTime();
        System.out.println(begin>end);
        System.out.println(begin<end);
        System.out.println(begin==end);
    }
}