1 /* 2 * Copyright (C) 2020 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 com.android.eventlib; 18 19 import java.io.ByteArrayInputStream; 20 import java.io.ByteArrayOutputStream; 21 import java.io.IOException; 22 import java.io.ObjectInput; 23 import java.io.ObjectInputStream; 24 import java.io.ObjectOutputStream; 25 import java.io.Serializable; 26 import java.time.Instant; 27 28 /** 29 * Represents a single action which has been logged. 30 */ 31 public abstract class Event implements Serializable { 32 33 private static final long serialVersionUID = 1; 34 35 // This class should contain all standard data applicable to all Events. 36 37 protected String mPackageName; 38 protected Instant mTimestamp; 39 40 /** Get the package name this event was logged by. */ packageName()41 public String packageName() { 42 return mPackageName; 43 } 44 45 /** Get the time that this event was logged. */ timestamp()46 public Instant timestamp() { 47 return mTimestamp; 48 } 49 50 /** 51 * Serialize the {@link Event} to a byte array. 52 * 53 * <p>The resulting array can be deserialized using {@link #fromBytes(byte[])}. 54 */ toBytes()55 byte[] toBytes() throws IOException { 56 try (ByteArrayOutputStream bos = new ByteArrayOutputStream(); 57 ObjectOutputStream out = new ObjectOutputStream(bos)) { 58 out.writeObject(this); 59 out.flush(); 60 return bos.toByteArray(); 61 } 62 } 63 64 /** 65 * Deserialize an {@link Event} from a byte array created using {@link #toBytes()}. 66 */ fromBytes(byte[] bytes)67 static Event fromBytes(byte[] bytes) throws IOException { 68 try (ByteArrayInputStream bis = new ByteArrayInputStream(bytes); 69 ObjectInput in = new ObjectInputStream(bis)) { 70 try { 71 return (Event) in.readObject(); 72 } catch (ClassNotFoundException e) { 73 throw new IllegalStateException( 74 "Trying to read Event which is not on classpath", e); 75 } 76 } 77 } 78 } 79