libgdx json

Introduction

The module is the recommended json serializer when using LibGDX or when you plan to target HTML5 now or in the future. Provides serialization for all odb platforms.

Setup

1. Add artemis-odb-serializer-json-libgdx module as dependency to your gradle/maven configuration. To your core module for LibGDX projects.

2. To your Html module:

   implementation "net.onedaybeard.artemis:artemis-odb-serializer:$artemisOdbVersion:sources"
implementation "net.onedaybeard.artemis:artemis-odb-serializer-json-libgdx:$artemisOdbVersion:sources"

3. To your GdxDefinition.gwt.xml: <inherits name="com.artemis-json-libgdx" />

4. Add the required manager and configure the json backend:

     final WorldSerializationManager manager = new WorldSerializationManager();
     World world = new World(new WorldConfiguration().setSystem(manager));
     manager.setSerializer(new JsonArtemisSerializer(world));

Using the serializer

Load from file

     final InputStream is = AnyClass.class.getResourceAsStream("level.json");
     manager.load(is, SaveFileFormat.class);

Anything already in the world is unaffected by the load, so you can incrementally load parts of a world.

Save to file

     final PrintWriter writer = new PrintWriter("level.json", "UTF-8");
     manager.save(writer, new SaveFileFormat(entities));
     writer.close();

Save to string

     final StringWriter writer = new StringWriter();
     manager.save(writer, new SaveFileFormat(entities));
     String json = writer.toString();

entities is an IntBag with entity IDs defining the scope of the save operation.

Full example:

private String subscriptionToJson(EntitySubscription subscription) {
	final StringWriter writer = new StringWriter();
	final SaveFileFormat save = new SaveFileFormat(subscription.getEntities());
	world.getSystem(WorldSerializationManager.class).save(writer, save);
	return writer.toString();
}

Usage (Browser)

Save World to Local Storage

final EntitySubscription allEntities = world.getManager(AspectSubscriptionManager.class).get(Aspect.all());

try {
	final ByteArrayOutputStream baos = new ByteArrayOutputStream();
	final SaveFileFormat save = new SaveFileFormat(allEntities.getEntities());
	world.getSystem(WorldSerializationManager.class).save(baos , save);

	final Preferences preferences = Gdx.app.getPreferences("MyGame");
	preferences.putString("MyStateId", baos.toString("UTF-8"));
	preferences.flush();
} catch (Exception e) {
	Gdx.app.error("MyGame", "Save Failed", e);
}  

Local storage has a quota in most browsers! Article about local storage quota

Load world from Local Storage

try {
	final Preferences preferences = Gdx.app.getPreferences("MyGame");
	final String json = preferences.getString("MyStateId");
	final ByteArrayInputStream is = new ByteArrayInputStream(json.getBytes("UTF-8"));
	world.getSystem(WorldSerializationManager.class).load(is,SaveFileFormat.class);
} catch (Exception e) {
	Gdx.app.error("MyGame", "Load Failed", e);
}