1 /* 2 * Copyright 2022 Google LLC 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.google.android.libraries.mobiledatadownload.file.openers; 17 18 import com.google.android.libraries.mobiledatadownload.file.OpenContext; 19 import com.google.android.libraries.mobiledatadownload.file.Opener; 20 import com.google.common.io.Files; 21 import java.io.File; 22 import java.io.IOException; 23 import java.io.RandomAccessFile; 24 25 /** Opener that returns a RandomAccessFile. */ 26 public final class RandomAccessFileOpener implements Opener<RandomAccessFile> { 27 28 private final boolean writeSupport; 29 30 /** 31 * If writeSupport is false, the RAF is read only. If writeSupport is enabled, the RAF is read and 32 * write, and the directory is created if necessary. 33 */ RandomAccessFileOpener(boolean writeSupport)34 private RandomAccessFileOpener(boolean writeSupport) { 35 this.writeSupport = writeSupport; 36 } 37 createForRead()38 public static RandomAccessFileOpener createForRead() { 39 return new RandomAccessFileOpener(/* writeSupport= */ false); 40 } 41 42 /** 43 * Create an opener that returns a RandomAccessFile opened for read and write. If the File or its 44 * parent directories do not exist, they will be created. 45 */ createForReadWrite()46 public static RandomAccessFileOpener createForReadWrite() { 47 return new RandomAccessFileOpener(/* writeSupport= */ true); 48 } 49 50 @Override open(OpenContext openContext)51 public RandomAccessFile open(OpenContext openContext) throws IOException { 52 if (writeSupport) { 53 ReadFileOpener readFileOpener = ReadFileOpener.create().withShortCircuit(); 54 File file = readFileOpener.open(openContext); 55 Files.createParentDirs(file); 56 return new RandomAccessFile(file, "rw"); 57 } else /* if (!writeSupport) */ { 58 ReadFileOpener readFileOpener = ReadFileOpener.create(); 59 File file = readFileOpener.open(openContext); 60 return new RandomAccessFile(file, "r"); 61 } 62 } 63 } 64