SavedStateHandleController.java
/*
* Copyright 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.lifecycle;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.savedstate.SavedStateRegistry;
import androidx.savedstate.SavedStateRegistryOwner;
final class SavedStateHandleController implements LifecycleEventObserver {
static final String TAG_SAVED_STATE_HANDLE_CONTROLLER = "androidx.lifecycle.savedstate.vm.tag";
private final String mKey;
private boolean mIsAttached = false;
private final SavedStateHandle mHandle;
SavedStateHandleController(String key, SavedStateHandle handle) {
mKey = key;
mHandle = handle;
}
boolean isAttached() {
return mIsAttached;
}
void attachToLifecycle(SavedStateRegistry registry, Lifecycle lifecycle) {
if (mIsAttached) {
throw new IllegalStateException("Already attached to lifecycleOwner");
}
mIsAttached = true;
lifecycle.addObserver(this);
registry.registerSavedStateProvider(mKey, mHandle.savedStateProvider());
}
@Override
public void onStateChanged(@NonNull LifecycleOwner source, @NonNull Lifecycle.Event event) {
if (event == Lifecycle.Event.ON_DESTROY) {
mIsAttached = false;
source.getLifecycle().removeObserver(this);
}
}
SavedStateHandle getHandle() {
return mHandle;
}
static SavedStateHandleController create(SavedStateRegistry registry, Lifecycle lifecycle,
String key, Bundle defaultArgs) {
Bundle restoredState = registry.consumeRestoredStateForKey(key);
SavedStateHandle handle = SavedStateHandle.createHandle(restoredState, defaultArgs);
SavedStateHandleController controller = new SavedStateHandleController(key, handle);
controller.attachToLifecycle(registry, lifecycle);
registry.runOnNextRecreation(OnRecreation.class);
return controller;
}
static final class OnRecreation implements SavedStateRegistry.AutoRecreated {
@Override
public void onRecreated(@NonNull SavedStateRegistryOwner owner) {
if (!(owner instanceof ViewModelStoreOwner)) {
throw new IllegalStateException(
"Internal error: OnRecreation should be registered only on components"
+ "that implement ViewModelStoreOwner");
}
ViewModelStore viewModelStore = ((ViewModelStoreOwner) owner).getViewModelStore();
SavedStateRegistry savedStateRegistry = owner.getSavedStateRegistry();
for (String key : viewModelStore.keys()) {
ViewModel viewModel = viewModelStore.get(key);
SavedStateHandleController controller = viewModel.getTag(
TAG_SAVED_STATE_HANDLE_CONTROLLER);
if (controller != null && !controller.isAttached()) {
controller.attachToLifecycle(owner.getSavedStateRegistry(),
owner.getLifecycle());
}
}
if (!viewModelStore.keys().isEmpty()) {
savedStateRegistry.runOnNextRecreation(OnRecreation.class);
}
}
}
}