在java中存储本地数据? [英] Store local data in java?

问题描述

我正在使用 Java 进行简单的文本冒险.我希望能够定义每个任务的进度，并将其存储在用户的应用程序数据中的某个位置，以便他们下次玩游戏时读取.我该怎么做?

I am using Java to make a simple text adventure. I want to be able to define progress each mission, and that will store somewhere in the user's appdata to be read next time they play the game. How can I do this?

推荐答案

如果您只想在内部存储数据(即，跨会话保存，但不是用户可读的文件)，我会使用 首选项 API.

If you just want to store the data internally (i.e., save across sessions, but not as a user-readable file), I would use the Preferences API.

例如:假设您有一个名为 MissionInfo 的类，它实现了 java.io.Serializable.您可以执行以下操作:

For example: consider that you have a class called MissionInfo which implements java.io.Serializable. You could do the following:

// Precondition: missionInfoToSave is an variable of type MissionInfo

// The key used to store the data.
final String key = "SAVE_DATA";

// Get the preferences database for this package.
Preferences prefs = Preferences.userNodeForPackage(MissionInfo.class);

// To save, write the object to a byte array.
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try {
    ObjectOutputStream oos = new ObjectOutputStream(baos);
    oos.writeObject(missionInfoToSave); // write it to the stream
    prefs.putByteArray(key, baos.toByteArray());
} catch (IOException ie) {
    System.err.println("Failed to save to file");
}

// To load, read it back.
// The second argument is the default if the key isn't found.
byte[] stored = prefs.getByteArray(key, null);
if (stored == null) {
    // There's no stored data.
    return;
}
ByteArrayInputStream bais = new ByteArrayInputStream();
try {
    ObjectInputStream ois = new ObjectInputStream(bais);
    Object o = ois.readObject();
    if (o instanceof MissionData) { 
        // Good: it's a saved data file.
        updateMissionProgress((MissionData) o); // assuming this is defined
    }
} catch (IOException ie) {
    System.err.println("Couldn't load from prefs");
} catch (ClassNotFoundException cnfe) {
    System.err.println("Class couldn't be found");
}

首选项 API 将跨会话存储数据.您可以在包 java.util.prefs.

The Preferences API will store the data across sessions. You can find it in the package java.util.prefs.

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