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.transforms; 17 18 import android.net.Uri; 19 import com.google.android.libraries.mobiledatadownload.file.common.Fragment; 20 import com.google.android.libraries.mobiledatadownload.file.spi.Transform; 21 import java.io.BufferedOutputStream; 22 import java.io.IOException; 23 import java.io.InputStream; 24 import java.io.OutputStream; 25 26 /** 27 * BufferTransform takes writes and holds on to it until enough has been written to justify flushing 28 * to the disk. Reads are not affected by this transform. 29 * 30 * <p>A flush of the buffer can be performed using {@link OutputStream#flush()}. 31 * 32 * <p>It is configured using transform fragment int param {@code size}. For example: {@code 33 * file:///tmp/file#transform=buffer(size=1024)}. 34 */ 35 public class BufferTransform implements Transform { 36 37 private static final int DEFAULT_BUFFER_SIZE = 8192; 38 39 private static final String TRANSFORM_NAME = "buffer"; 40 private static final String SUBPARAM_SIZE = "size"; 41 42 @Override name()43 public String name() { 44 return TRANSFORM_NAME; 45 } 46 47 @Override wrapForRead(Uri uri, InputStream wrapped)48 public InputStream wrapForRead(Uri uri, InputStream wrapped) throws IOException { 49 return wrapped; 50 } 51 52 @Override wrapForAppend(Uri uri, OutputStream wrapped)53 public OutputStream wrapForAppend(Uri uri, OutputStream wrapped) throws IOException { 54 return wrapForWrite(uri, wrapped); 55 } 56 57 @Override wrapForWrite(Uri uri, OutputStream wrapped)58 public OutputStream wrapForWrite(Uri uri, OutputStream wrapped) throws IOException { 59 String bufferSizeStr = Fragment.getTransformSubParam(uri, name(), SUBPARAM_SIZE); 60 int bufferSize = DEFAULT_BUFFER_SIZE; 61 if (bufferSizeStr != null) { 62 bufferSize = Integer.parseInt(bufferSizeStr); 63 } 64 return new BufferedOutputStream(wrapped, bufferSize); 65 } 66 } 67