java获取系统指定时间年月日

java获取系统指定时间年月日

    private String setDateTime(String falg) {
        Calendar c = Calendar.getInstance();
        c.setTimeInMillis(new Date().getTime());
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
        SimpleDateFormat dateMouthFormat = new SimpleDateFormat("yyyy-MM");
        SimpleDateFormat dateYearFormat = new SimpleDateFormat("yyyy");
        if (falg.equals("daystartTime")) {
            c.add(Calendar.DATE, -45);
            return dateFormat.format(c.getTime());
        } else if (falg.equals("dayendTime")) {
            return dateFormat.format(c.getTime());
        } else if (falg.equals("MouthstartTime")) {
            c.add(Calendar.YEAR, -1);
            return dateMouthFormat.format(c.getTime());
        } else if (falg.equals("MouthendTime")) {
            return dateMouthFormat.format(c.getTime());
        } else if (falg.equals("YearstartTime")) {
            c.add(Calendar.YEAR, -3);
            return dateYearFormat.format(c.getTime());
        } else if (falg.equals("YearendTime")) {
            return dateYearFormat.format(c.getTime());
        } else {
            return null;
        }
    }