把对象(数据)保存下来.

没有数据怎么办?用虚拟数据呗....所以有的时候把一些数据保存到文件中也是很有用的.
    List l = new ArrayList();
        l.add("abc");
        l.add("abc");
        l.add("abc");
        l.add("abc");
        ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(
                new File("a.txt")));
        oos.writeObject(l);
        oos.flush();
        oos.close();
        ObjectInputStream ois = new ObjectInputStream(new FileInputStream(
                new File("a.txt")));
        List list = (List) ois.readObject();

        for (Iterator iterator = list.iterator(); iterator.hasNext();) {
            Object object = (Object) iterator.next();
            System.out.print(object + "\t");
        }
        System.out.println();

只有公司的IP才能访问数据...郁闷,所以才想到这招.