| /* |
| * Copyright (C) 2018 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 com.android.server; |
| |
| import android.annotation.NonNull; |
| import android.annotation.Nullable; |
| import android.os.FileUtils; |
| import android.util.Slog; |
| |
| import java.io.File; |
| import java.io.IOException; |
| |
| /** |
| * A specialized ExtconUEventObserver that on receiving a {@link UEvent} calls {@link |
| * #updateState(ExtconInfo, String, S)} with the value of{@link #parseState(ExtconInfo, String)}. |
| * |
| * @param <S> the type of state to parse and update |
| * @hide |
| */ |
| public abstract class ExtconStateObserver<S> extends ExtconUEventObserver { |
| private static final String TAG = "ExtconStateObserver"; |
| private static final boolean LOG = false; |
| |
| /** |
| * Parses the current state from the state file for {@code extconInfo}. |
| * |
| * @param extconInfo the extconInfo to parse state for |
| * @see #parseState(ExtconInfo, String) |
| * @see ExtconInfo#getStatePath() |
| */ |
| @Nullable |
| public S parseStateFromFile(ExtconInfo extconInfo) throws IOException { |
| String statePath = extconInfo.getStatePath(); |
| return parseState( |
| extconInfo, |
| FileUtils.readTextFile(new File(statePath), 0, null).trim()); |
| } |
| |
| @Override |
| public void onUEvent(ExtconInfo extconInfo, UEvent event) { |
| if (LOG) Slog.d(TAG, extconInfo.getName() + " UEVENT: " + event); |
| String name = event.get("NAME"); |
| S state = parseState(extconInfo, event.get("STATE")); |
| if (state != null) { |
| updateState(extconInfo, name, state); |
| } |
| } |
| |
| /** |
| * Subclasses of ExtconStateObserver should override this method update state for {@code |
| * exconInfo} from an {@code UEvent}. |
| * |
| * @param extconInfo the external connection |
| * @param eventName the {@code NAME} of the {@code UEvent} |
| * @param state the{@code STATE} as parsed by {@link #parseState(ExtconInfo, String)}. |
| */ |
| public abstract void updateState(ExtconInfo extconInfo, String eventName, @NonNull S state); |
| |
| /** |
| * Subclasses of ExtconStateObserver should override this method to parse the {@code STATE} from |
| * an UEvent. |
| * |
| * @param extconInfo that matches the {@code DEVPATH} of {@code event} |
| * @param state the {@code STATE} from a {@code UEvent}. |
| * @return the parsed state. Return null if the state can not be parsed. |
| */ |
| @Nullable |
| public abstract S parseState(ExtconInfo extconInfo, String state); |
| } |