1 /* 2 * Copyright (C) 2018 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 package com.android.server; 17 18 import android.annotation.NonNull; 19 import android.annotation.Nullable; 20 import android.os.FileUtils; 21 import android.util.Slog; 22 23 import java.io.File; 24 import java.io.IOException; 25 26 /** 27 * A specialized ExtconUEventObserver that on receiving a {@link UEvent} calls {@link 28 * #updateState(ExtconInfo, String, S)} with the value of{@link #parseState(ExtconInfo, String)}. 29 * 30 * @param <S> the type of state to parse and update 31 * @hide 32 */ 33 public abstract class ExtconStateObserver<S> extends ExtconUEventObserver { 34 private static final String TAG = "ExtconStateObserver"; 35 private static final boolean LOG = false; 36 37 /** 38 * Parses the current state from the state file for {@code extconInfo}. 39 * 40 * @param extconInfo the extconInfo to parse state for 41 * @see #parseState(ExtconInfo, String) 42 * @see ExtconInfo#getStatePath() 43 */ 44 @Nullable parseStateFromFile(ExtconInfo extconInfo)45 public S parseStateFromFile(ExtconInfo extconInfo) throws IOException { 46 String statePath = extconInfo.getStatePath(); 47 return parseState( 48 extconInfo, 49 FileUtils.readTextFile(new File(statePath), 0, null).trim()); 50 } 51 52 @Override onUEvent(ExtconInfo extconInfo, UEvent event)53 public void onUEvent(ExtconInfo extconInfo, UEvent event) { 54 if (LOG) Slog.d(TAG, extconInfo.getName() + " UEVENT: " + event); 55 String name = event.get("NAME"); 56 S state = parseState(extconInfo, event.get("STATE")); 57 if (state != null) { 58 updateState(extconInfo, name, state); 59 } 60 } 61 62 /** 63 * Subclasses of ExtconStateObserver should override this method update state for {@code 64 * exconInfo} from an {@code UEvent}. 65 * 66 * @param extconInfo the external connection 67 * @param eventName the {@code NAME} of the {@code UEvent} 68 * @param state the{@code STATE} as parsed by {@link #parseState(ExtconInfo, String)}. 69 */ updateState(ExtconInfo extconInfo, String eventName, @NonNull S state)70 public abstract void updateState(ExtconInfo extconInfo, String eventName, @NonNull S state); 71 72 /** 73 * Subclasses of ExtconStateObserver should override this method to parse the {@code STATE} from 74 * an UEvent. 75 * 76 * @param extconInfo that matches the {@code DEVPATH} of {@code event} 77 * @param state the {@code STATE} from a {@code UEvent}. 78 * @return the parsed state. Return null if the state can not be parsed. 79 */ 80 @Nullable parseState(ExtconInfo extconInfo, String state)81 public abstract S parseState(ExtconInfo extconInfo, String state); 82 } 83