乘法超过int最大值时 使用long

long l = System.currentTimeMillis();
        System.out.println(l);
        long diff = ((long) 150) * 24 * 60 * 60 * 1000;
        System.out.println(diff);
        //12960000000
        long a = l - 12960000000l;
        a = l - diff;
        System.out.println(a);