Java:从磁盘写入/读取映射 [英] Java: Writing/Reading a Map from disk

问题描述

我有一个数据结构，我希望能够在关闭程序之前将其写入文件，然后在下次应用程序启动时从文件中读取数据以重新填充该结构.

I have a data structure that I would like to be able to write to a file before closing the program, and then read from the file to re-populate the structure the next time the application starts.

我的结构是HashMap<String, Object>.该对象非常简单.对于成员变量，它具有一个String和两个布尔类型的小型本机数组.这是一个真正简单的应用程序，我希望一次不会超过10-15个<key,value>对.

My structure is HashMap<String, Object>. The Object is pretty simple; For member variables it has a String, and two small native arrays of type Boolean. This is a real simple application, and I wouldn't expect more than 10-15 <key,value> pairs at one time.

我一直在尝试(不成功)对象输入/输出流.我需要使对象类可序列化吗?

I have been experimenting (unsuccessfully) with Object input/output streams. Do I need to make the Object class Serializable?

您能给我有关最佳方法的任何建议吗?我只需要向正确的方向推进即可.谢谢！

Can you give me any suggestions on the best way to do this? I just need a push in the right direction. Thanks!

好吧，我仍然感到愚蠢，我正在一张地图上书写并读入另一张地图，然后比较它们以检查我的结果.显然我在比较它们是错误的.叹气.

Well I feel dumb still, I was writing from one map and reading into another map, and then comparing them to check my results. Apparently I was comparing them wrong. Sigh.

推荐答案

如果您不特别关注Object，则只需要String，String键值对，那么我建议您使用

If you aren't concerned about Object particularly , you just need key value pair of String,String then I would suggest you to go for java.util.Properties. otherwise here you go

        Map map = new HashMap();
        map.put("1",new Integer(1));
        map.put("2",new Integer(2));
        map.put("3",new Integer(3));
        FileOutputStream fos = new FileOutputStream("map.ser");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        oos.writeObject(map);
        oos.close();

        FileInputStream fis = new FileInputStream("map.ser");
        ObjectInputStream ois = new ObjectInputStream(fis);
        Map anotherMap = (Map) ois.readObject();
        ois.close();

        System.out.println(anotherMap);

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