使用java的Calendar对象获得当前日期

/**   * @param flag true：开始日期；false：结束日期   * @return   */  public static String getLastQuarterTime(boolean flag){    SimpleDateFormat shortSdf = new SimpleDateFormat("yyyy-MM-dd");    SimpleDateFormat longSdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");         String resultDate="";    Date now = null;    try {      Calendar calendar = Calendar.getInstance();      int currentMonth = calendar.get(Calendar.MONTH) + 1;      //true：开始日期；false：结束日期      if(flag){        if (currentMonth >= 1 && currentMonth <= 3)          calendar.set(Calendar.MONTH, 0);        else if (currentMonth >= 4 && currentMonth <= 6)          calendar.set(Calendar.MONTH, 3);        else if (currentMonth >= 7 && currentMonth <= 9)          calendar.set(Calendar.MONTH, 6);        else if (currentMonth >= 10 && currentMonth <= 12)          calendar.set(Calendar.MONTH, 9);        calendar.set(Calendar.DATE, 1);                 now = longSdf.parse(shortSdf.format(calendar.getTime()) + " 00:00:00");      }else{        if (currentMonth >= 1 && currentMonth <= 3) {          calendar.set(Calendar.MONTH, 2);          calendar.set(Calendar.DATE, 31);        } else if (currentMonth >= 4 && currentMonth <= 6) {          calendar.set(Calendar.MONTH, 5);          calendar.set(Calendar.DATE, 30);        } else if (currentMonth >= 7 && currentMonth <= 9) {          calendar.set(Calendar.MONTH, 8);          calendar.set(Calendar.DATE, 30);        } else if (currentMonth >= 10 && currentMonth <= 12) {          calendar.set(Calendar.MONTH, 11);          calendar.set(Calendar.DATE, 31);        }        now = longSdf.parse(shortSdf.format(calendar.getTime()) + " 23:59:59");      }      calendar.setTime(now);// 设置日期      calendar.add(Calendar.MONTH, -3);      resultDate = longSdf.format(calendar.getTime());           } catch (Exception e) {      ;    }    return resultDate;  }