如何在 LIBGDX android 应用程序中获取上下文（）

Question

I need to get the Context of my app but in my main Class extends from Game so I can not extends from Activity . Does anybody know how to do it?

Thank you!

Answer 1

LibGDX is a cross-platform game engine, so your application can be executed on multiple platforms. Only Android, which is just one supported platform, can provide a Context object.

To get around this issue, you'll need to create an Interface in the core module of your LibGDX project. That Interface can, for example, contain a getContext() method. Add the interface as an argument in the constructor of your main LibGDX class. In every platform-specific module, you should then implement this Interface , override the getContext() method (by returning a Context object in the android module and null in every other module) and pass it with the constructor for the main LibGDX class in the Launcher class for that module.

For more information about the topic, read the LibGDX Wiki: https://github.com/libgdx/libgdx/wiki/Interfacing-with-platform-specific-code

EDIT: LibGDX isn't able to handle the Context object, you'll need to manipulate the Context object in the Android module, instead of passing it to the core module! Thanks to @Nicolas and @Luis Fernando Frontanilla for mentioning this.

Answer 2

Interfacing is the way to go since you can't access Android specific code from Core module.

Step 1: Create the interface (CORE MODULE)

public interface MyInterface {

    void manipulateContext();

    void manipulateContextWithExtraParams(String example, int example2);
}

Step 2: Implement the interface (ANDROID MODULE)

import android.content.Context;

public class InterfaceImplementation implements MyInterface {

    private Context context;

    public InterfaceImplementation(Context context) {
        // Store the context for later use
        this.context = context;
    }

    @Override
    public void manipulateContext() {
        // Do something with the context, this is called on the core module
        System.out.println(context);
    }

    @Override
    public void manipulateContextWithExtraParams(String example, int example2) {
        if (example2 == 1) {
            System.out.println(example + context);
        } else {
            System.out.println(example);
        }
    }
}

Step 3: Send the implemented interface your game (ANDROID MODULE)

import android.os.Bundle;

import com.badlogic.gdx.backends.android.AndroidApplication;
import com.badlogic.gdx.backends.android.AndroidApplicationConfiguration;
import com.frontanilla.helping.getcontext.InterfaceImplementation;
import com.frontanilla.helping.getcontext.MyGame;

public class AndroidLauncher extends AndroidApplication {
    @Override
    protected void onCreate (Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        AndroidApplicationConfiguration config = new AndroidApplicationConfiguration();

        InterfaceImplementation interfaceImplementation = new InterfaceImplementation(this);

        // Here we send the implementation to our Game in Core module
        initialize(new MyGame(interfaceImplementation), config);
    }
}

Step 4: Store and use the methods you defined on your interface (CORE MODULE)

import com.badlogic.gdx.Game;

public class MyGame extends Game {

    private MyInterface myInterface;

    public MyGame(MyInterface myInterface) {
        // Store for later use
        this.myInterface = myInterface;
    }

    @Override
    public void create() {
        // Example of manipulating the Android Context indirectly from Core module
        myInterface.manipulateContext();
        myInterface.manipulateContextWithExtraParams("Hello", 2);
    }
}

As you can see, you will not be manipulating the Context from the core module directly, instead, place that logic on the InterfaceImplementation class

Answer 3

What I have tried is:

scoreHelper = new ScoreSQLiteHelper(context,"dbtest",null,1); db = scoreHelper.getWritableDatabase();

but I don't have any context to feed that method.

It would be usefull any other way to get a path to create the db with:

db = SQLiteDatabase.openOrCreateDatabase(path,null);