content: /*
   * 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 com.android.server.backup.utils;
  
  import java.io.BufferedOutputStream;
  import java.io.DataInputStream;
  import java.io.DataOutputStream;
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileOutputStream;
  import java.io.IOException;
  
  /**
   * Provides an interface for serializing an object to a file and deserializing it back again.
   *
   * <p>Serialization logic is implemented as a {@link DataStreamCodec}.
   *
   * @param <T> The type of object to serialize / deserialize.
   */
  public final class DataStreamFileCodec<T> {
      private final File mFile;
      private final DataStreamCodec<T> mCodec;
  
      /**
       * Constructs an instance to serialize to or deserialize from the given file, with the given
       * serialization / deserialization strategy.
       */
      public DataStreamFileCodec(File file, DataStreamCodec<T> codec) {
          mFile = file;
          mCodec = codec;
      }
  
      /**
       * Deserializes a {@code T} from the file, automatically closing input streams.
       *
       * @return The deserialized object.
       * @throws IOException if an IO error occurred.
       */
      public T deserialize() throws IOException {
          try (
              FileInputStream fileInputStream = new FileInputStream(mFile);
              DataInputStream dataInputStream = new DataInputStream(fileInputStream)
          ) {
              return mCodec.deserialize(dataInputStream);
          }
      }
  
      /**
       * Serializes {@code t} to the file, automatically flushing and closing output streams.
       *
       * @param t The object to serialize.
       * @throws IOException if an IO error occurs.
       */
      public void serialize(T t) throws IOException {
          try (
              FileOutputStream fileOutputStream = new FileOutputStream(mFile);
              BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(fileOutputStream);
              DataOutputStream dataOutputStream = new DataOutputStream(bufferedOutputStream)
          ) {
              mCodec.serialize(t, dataOutputStream);
              dataOutputStream.flush();
          }
      }
  }
  