| /* |
| * Copyright (C) 2017 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 android.arch.lifecycle; |
| |
| import android.arch.lifecycle.Lifecycle.Event; |
| |
| import java.lang.reflect.InvocationTargetException; |
| import java.lang.reflect.Method; |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.Map.Entry; |
| |
| /** |
| * An internal implementation of {@link GenericLifecycleObserver} that relies on reflection. |
| */ |
| class ReflectiveGenericLifecycleObserver implements GenericLifecycleObserver { |
| private final Object mWrapped; |
| private final CallbackInfo mInfo; |
| @SuppressWarnings("WeakerAccess") |
| static final Map<Class, CallbackInfo> sInfoCache = new HashMap<>(); |
| |
| ReflectiveGenericLifecycleObserver(Object wrapped) { |
| mWrapped = wrapped; |
| mInfo = getInfo(mWrapped.getClass()); |
| } |
| |
| @Override |
| public void onStateChanged(LifecycleOwner source, Event event) { |
| invokeCallbacks(mInfo, source, event); |
| } |
| |
| private void invokeMethodsForEvent(List<MethodReference> handlers, LifecycleOwner source, |
| Event event) { |
| if (handlers != null) { |
| for (int i = handlers.size() - 1; i >= 0; i--) { |
| MethodReference reference = handlers.get(i); |
| invokeCallback(reference, source, event); |
| } |
| } |
| } |
| |
| @SuppressWarnings("ConstantConditions") |
| private void invokeCallbacks(CallbackInfo info, LifecycleOwner source, Event event) { |
| invokeMethodsForEvent(info.mEventToHandlers.get(event), source, event); |
| invokeMethodsForEvent(info.mEventToHandlers.get(Event.ON_ANY), source, event); |
| } |
| |
| private void invokeCallback(MethodReference reference, LifecycleOwner source, Event event) { |
| //noinspection TryWithIdenticalCatches |
| try { |
| switch (reference.mCallType) { |
| case CALL_TYPE_NO_ARG: |
| reference.mMethod.invoke(mWrapped); |
| break; |
| case CALL_TYPE_PROVIDER: |
| reference.mMethod.invoke(mWrapped, source); |
| break; |
| case CALL_TYPE_PROVIDER_WITH_EVENT: |
| reference.mMethod.invoke(mWrapped, source, event); |
| break; |
| } |
| } catch (InvocationTargetException e) { |
| throw new RuntimeException("Failed to call observer method", e.getCause()); |
| } catch (IllegalAccessException e) { |
| throw new RuntimeException(e); |
| } |
| } |
| |
| private static CallbackInfo getInfo(Class klass) { |
| CallbackInfo existing = sInfoCache.get(klass); |
| if (existing != null) { |
| return existing; |
| } |
| existing = createInfo(klass); |
| return existing; |
| } |
| |
| private static void verifyAndPutHandler(Map<MethodReference, Event> handlers, |
| MethodReference newHandler, Event newEvent, Class klass) { |
| Event event = handlers.get(newHandler); |
| if (event != null && newEvent != event) { |
| Method method = newHandler.mMethod; |
| throw new IllegalArgumentException( |
| "Method " + method.getName() + " in " + klass.getName() |
| + " already declared with different @OnLifecycleEvent value: previous" |
| + " value " + event + ", new value " + newEvent); |
| } |
| if (event == null) { |
| handlers.put(newHandler, newEvent); |
| } |
| } |
| |
| private static CallbackInfo createInfo(Class klass) { |
| Class superclass = klass.getSuperclass(); |
| Map<MethodReference, Event> handlerToEvent = new HashMap<>(); |
| if (superclass != null) { |
| CallbackInfo superInfo = getInfo(superclass); |
| if (superInfo != null) { |
| handlerToEvent.putAll(superInfo.mHandlerToEvent); |
| } |
| } |
| |
| Method[] methods = klass.getDeclaredMethods(); |
| |
| Class[] interfaces = klass.getInterfaces(); |
| for (Class intrfc : interfaces) { |
| for (Entry<MethodReference, Event> entry : getInfo(intrfc).mHandlerToEvent.entrySet()) { |
| verifyAndPutHandler(handlerToEvent, entry.getKey(), entry.getValue(), klass); |
| } |
| } |
| |
| for (Method method : methods) { |
| OnLifecycleEvent annotation = method.getAnnotation(OnLifecycleEvent.class); |
| if (annotation == null) { |
| continue; |
| } |
| Class<?>[] params = method.getParameterTypes(); |
| int callType = CALL_TYPE_NO_ARG; |
| if (params.length > 0) { |
| callType = CALL_TYPE_PROVIDER; |
| if (!params[0].isAssignableFrom(LifecycleOwner.class)) { |
| throw new IllegalArgumentException( |
| "invalid parameter type. Must be one and instanceof LifecycleOwner"); |
| } |
| } |
| Event event = annotation.value(); |
| |
| if (params.length > 1) { |
| callType = CALL_TYPE_PROVIDER_WITH_EVENT; |
| if (!params[1].isAssignableFrom(Event.class)) { |
| throw new IllegalArgumentException( |
| "invalid parameter type. second arg must be an event"); |
| } |
| if (event != Event.ON_ANY) { |
| throw new IllegalArgumentException( |
| "Second arg is supported only for ON_ANY value"); |
| } |
| } |
| if (params.length > 2) { |
| throw new IllegalArgumentException("cannot have more than 2 params"); |
| } |
| MethodReference methodReference = new MethodReference(callType, method); |
| verifyAndPutHandler(handlerToEvent, methodReference, event, klass); |
| } |
| CallbackInfo info = new CallbackInfo(handlerToEvent); |
| sInfoCache.put(klass, info); |
| return info; |
| } |
| |
| @SuppressWarnings("WeakerAccess") |
| static class CallbackInfo { |
| final Map<Event, List<MethodReference>> mEventToHandlers; |
| final Map<MethodReference, Event> mHandlerToEvent; |
| |
| CallbackInfo(Map<MethodReference, Event> handlerToEvent) { |
| mHandlerToEvent = handlerToEvent; |
| mEventToHandlers = new HashMap<>(); |
| for (Entry<MethodReference, Event> entry : handlerToEvent.entrySet()) { |
| Event event = entry.getValue(); |
| List<MethodReference> methodReferences = mEventToHandlers.get(event); |
| if (methodReferences == null) { |
| methodReferences = new ArrayList<>(); |
| mEventToHandlers.put(event, methodReferences); |
| } |
| methodReferences.add(entry.getKey()); |
| } |
| } |
| } |
| |
| @SuppressWarnings("WeakerAccess") |
| static class MethodReference { |
| final int mCallType; |
| final Method mMethod; |
| |
| MethodReference(int callType, Method method) { |
| mCallType = callType; |
| mMethod = method; |
| mMethod.setAccessible(true); |
| } |
| |
| @Override |
| public boolean equals(Object o) { |
| if (this == o) { |
| return true; |
| } |
| if (o == null || getClass() != o.getClass()) { |
| return false; |
| } |
| |
| MethodReference that = (MethodReference) o; |
| return mCallType == that.mCallType && mMethod.getName().equals(that.mMethod.getName()); |
| } |
| |
| @Override |
| public int hashCode() { |
| return 31 * mCallType + mMethod.getName().hashCode(); |
| } |
| } |
| |
| private static final int CALL_TYPE_NO_ARG = 0; |
| private static final int CALL_TYPE_PROVIDER = 1; |
| private static final int CALL_TYPE_PROVIDER_WITH_EVENT = 2; |
| } |