java的几个format

	public static String formatDateToString(long date) {
        SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMddHHmmssSSS");
        return formatter.format(date);
    }

	public String formatDate(Date date){
		SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
		return formatter.format(date);
	}
	//时间戳的格式化，当前时间往前推7天的时间戳：new Date().getTime()-7*24*3600*1000;
	public String formatDate(long date){
		SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
		return formatter.format(date);
	}

	public long formatDate(String date){
        SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
        Date d = null;
        try {
            d = formatter.parse(date);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return d.getTime();
    }

	//相除的两个数，在JAVA中，应该用double类型的，保留两位小数点
	public double decimalFormat(double f){
		DecimalFormat decimalFormat=new DecimalFormat(".00");
		return Double.valueOf(decimalFormat.format(f));
	}

	public double decimalFormat(long a, long b){
		DecimalFormat decimalFormat=new DecimalFormat(".00");
		return Double.valueOf(decimalFormat.format((double)a/b));
	}