1 /* 2 * Copyright (C) 2021 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package android.content; 18 19 import android.annotation.NonNull; 20 import android.content.res.Configuration; 21 22 import com.android.internal.annotations.GuardedBy; 23 24 import java.util.ArrayList; 25 import java.util.List; 26 import java.util.function.Consumer; 27 28 /** 29 * A helper class to manage {@link ComponentCallbacks} and {@link ComponentCallbacks2}, such as 30 * registering ,unregistering {@link ComponentCallbacks} and sending callbacks to all registered 31 * {@link ComponentCallbacks}. 32 * 33 * @see Context#registerComponentCallbacks(ComponentCallbacks) 34 * @see Context#unregisterComponentCallbacks(ComponentCallbacks) 35 * @see ComponentCallbacks 36 * @see ComponentCallbacks2 37 * 38 * @hide 39 */ 40 public class ComponentCallbacksController { 41 @GuardedBy("mLock") 42 private List<ComponentCallbacks> mComponentCallbacks; 43 44 private final Object mLock = new Object(); 45 46 /** 47 * Register the {@link ComponentCallbacks}. 48 * 49 * @see Context#registerComponentCallbacks(ComponentCallbacks) 50 */ registerCallbacks(@onNull ComponentCallbacks callbacks)51 public void registerCallbacks(@NonNull ComponentCallbacks callbacks) { 52 synchronized (mLock) { 53 if (mComponentCallbacks == null) { 54 mComponentCallbacks = new ArrayList<>(); 55 } 56 mComponentCallbacks.add(callbacks); 57 } 58 } 59 60 /** 61 * Unregister the {@link ComponentCallbacks}. 62 * 63 * @see Context#unregisterComponentCallbacks(ComponentCallbacks) 64 */ unregisterCallbacks(@onNull ComponentCallbacks callbacks)65 public void unregisterCallbacks(@NonNull ComponentCallbacks callbacks) { 66 synchronized (mLock) { 67 if (mComponentCallbacks == null || mComponentCallbacks.isEmpty()) { 68 return; 69 } 70 mComponentCallbacks.remove(callbacks); 71 } 72 } 73 74 /** 75 * Clear all registered {@link ComponentCallbacks}. 76 * It is useful when the associated {@link Context} is going to be released. 77 */ clearCallbacks()78 public void clearCallbacks() { 79 synchronized (mLock) { 80 if (mComponentCallbacks != null) { 81 mComponentCallbacks.clear(); 82 } 83 } 84 } 85 86 /** 87 * Sending {@link ComponentCallbacks#onConfigurationChanged(Configuration)} to all registered 88 * {@link ComponentCallbacks}. 89 */ dispatchConfigurationChanged(@onNull Configuration newConfig)90 public void dispatchConfigurationChanged(@NonNull Configuration newConfig) { 91 forAllComponentCallbacks(callbacks -> callbacks.onConfigurationChanged(newConfig)); 92 } 93 94 /** 95 * Sending {@link ComponentCallbacks#onLowMemory()} to all registered 96 * {@link ComponentCallbacks}. 97 */ dispatchLowMemory()98 public void dispatchLowMemory() { 99 forAllComponentCallbacks(ComponentCallbacks::onLowMemory); 100 } 101 102 /** 103 * Sending {@link ComponentCallbacks2#onTrimMemory(int)} to all registered 104 * {@link ComponentCallbacks2}. 105 */ dispatchTrimMemory(int level)106 public void dispatchTrimMemory(int level) { 107 forAllComponentCallbacks(callbacks -> { 108 if (callbacks instanceof ComponentCallbacks2) { 109 ((ComponentCallbacks2) callbacks).onTrimMemory(level); 110 } 111 }); 112 } 113 forAllComponentCallbacks(Consumer<ComponentCallbacks> callbacksConsumer)114 private void forAllComponentCallbacks(Consumer<ComponentCallbacks> callbacksConsumer) { 115 final ComponentCallbacks[] callbacksArray; 116 synchronized (mLock) { 117 if (mComponentCallbacks == null || mComponentCallbacks.isEmpty()) { 118 return; 119 } 120 callbacksArray = new ComponentCallbacks[mComponentCallbacks.size()]; 121 mComponentCallbacks.toArray(callbacksArray); 122 } 123 for (ComponentCallbacks callbacks : callbacksArray) { 124 callbacksConsumer.accept(callbacks); 125 } 126 } 127 } 128