如何在Android应用程序的整个生命周期中保持全局db4o

Question

We are developing an Android application that uses db4o for storing various objects throughout multiple activities and services. We are looking for the best approach on working with db4o and specifically when to open and close the db. We don't want to close the db after each single store operation and reopen it on every single retrieve operation because that could impact the speed of the application as opening and closing is hard on the processor. We prefer to keep a global state of the db4o that can be used throughout the app's lifecycle.

I was reading here global db4o database for multiple activities that is a good idea to keep the database on a Custom Application Object and get an instance when we need it:

public class MyApplication extends Application {
    private volatile ObjectContainer container;
    @Override
    public void onCreate() {
        super.onCreate();
        // the application object is a regular Android context,
        // So you can get the required info`
        this.container = Db4oEmbedded.openFile(...)
    }

    @Override
    public void onTerminate() {
        super.onTerminate();
        // if something was not finished, better rollback
        container.rollback();
        container.close();
    }

    public ObjectContainer database(){
        return container;
    }
}

However, I realised that the onTerminate() method of the Application exists only for emulation purposes and is never executed on an actual phone. And my question is, if the onTerminate() is never called where should we close the db object, and was is the best strategy on opening and closing?

Answer 1

您可以在应用程序类中创建延迟加载单例实例，然后在Launching Activity的OnCreate方法中对其进行初始化（打开），然后在onDestroy中将其关闭。