1 /* 2 * Copyright (C) 2017 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.server.backup.utils; 18 19 import java.io.BufferedOutputStream; 20 import java.io.DataInputStream; 21 import java.io.DataOutputStream; 22 import java.io.File; 23 import java.io.FileInputStream; 24 import java.io.FileOutputStream; 25 import java.io.IOException; 26 27 /** 28 * Provides an interface for serializing an object to a file and deserializing it back again. 29 * 30 * <p>Serialization logic is implemented as a {@link DataStreamCodec}. 31 * 32 * @param <T> The type of object to serialize / deserialize. 33 */ 34 public final class DataStreamFileCodec<T> { 35 private final File mFile; 36 private final DataStreamCodec<T> mCodec; 37 38 /** 39 * Constructs an instance to serialize to or deserialize from the given file, with the given 40 * serialization / deserialization strategy. 41 */ 42 public DataStreamFileCodec(File file, DataStreamCodec<T> codec) { 43 mFile = file; 44 mCodec = codec; 45 } 46 47 /** 48 * Deserializes a {@code T} from the file, automatically closing input streams. 49 * 50 * @return The deserialized object. 51 * @throws IOException if an IO error occurred. 52 */ 53 public T deserialize() throws IOException { 54 try ( 55 FileInputStream fileInputStream = new FileInputStream(mFile); 56 DataInputStream dataInputStream = new DataInputStream(fileInputStream) 57 ) { 58 return mCodec.deserialize(dataInputStream); 59 } 60 } 61 62 /** 63 * Serializes {@code t} to the file, automatically flushing and closing output streams. 64 * 65 * @param t The object to serialize. 66 * @throws IOException if an IO error occurs. 67 */ 68 public void serialize(T t) throws IOException { 69 try ( 70 FileOutputStream fileOutputStream = new FileOutputStream(mFile); 71 BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fileOutputStream); 72 DataOutputStream dataOutputStream = new DataOutputStream(bufferedOutputStream) 73 ) { 74 mCodec.serialize(t, dataOutputStream); 75 dataOutputStream.flush(); 76 } 77 } 78 } 79
