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.samples; 17 18 import static com.google.android.libraries.mobiledatadownload.file.common.internal.Charsets.US_ASCII; 19 import static com.google.android.libraries.mobiledatadownload.file.common.internal.Charsets.UTF_8; 20 21 import android.net.Uri; 22 import com.google.android.libraries.mobiledatadownload.file.common.UnsupportedFileStorageOperation; 23 import com.google.android.libraries.mobiledatadownload.file.spi.Transform; 24 import com.google.common.io.BaseEncoding; 25 import java.io.IOException; 26 import java.io.InputStream; 27 import java.io.InputStreamReader; 28 import java.io.OutputStream; 29 import java.io.OutputStreamWriter; 30 import java.io.Reader; 31 import java.io.Writer; 32 33 /** A demo transform that encodes/decodes to base64. */ 34 public final class Base64Transform implements Transform { 35 36 @Override name()37 public String name() { 38 return "base64"; 39 } 40 41 @Override wrapForRead(Uri uri, InputStream wrapped)42 public InputStream wrapForRead(Uri uri, InputStream wrapped) throws IOException { 43 Reader reader = new InputStreamReader(wrapped, US_ASCII.newDecoder()); 44 return BaseEncoding.base64().decodingStream(reader); 45 } 46 47 @Override wrapForWrite(Uri uri, OutputStream wrapped)48 public OutputStream wrapForWrite(Uri uri, OutputStream wrapped) throws IOException { 49 Writer writer = new OutputStreamWriter(wrapped, US_ASCII.newEncoder()); 50 return BaseEncoding.base64().encodingStream(writer); 51 } 52 53 @Override wrapForAppend(Uri uri, OutputStream wrapped)54 public OutputStream wrapForAppend(Uri uri, OutputStream wrapped) throws IOException { 55 throw new UnsupportedFileStorageOperation("Cannot append to encoded file because of padding."); 56 } 57 58 @Override encode(Uri uri, String filename)59 public String encode(Uri uri, String filename) { 60 return BaseEncoding.base64().encode(filename.getBytes()); 61 } 62 63 @Override decode(Uri uri, String filename)64 public String decode(Uri uri, String filename) { 65 return new String(BaseEncoding.base64().decode(filename), UTF_8); 66 } 67 } 68