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.bips.discovery; 18 19 import android.net.Uri; 20 import android.util.JsonReader; 21 import android.util.JsonWriter; 22 import android.util.Log; 23 24 import com.android.bips.BuiltInPrintService; 25 26 import java.io.BufferedReader; 27 import java.io.BufferedWriter; 28 import java.io.File; 29 import java.io.FileReader; 30 import java.io.FileWriter; 31 import java.io.IOException; 32 import java.util.ArrayList; 33 import java.util.Arrays; 34 import java.util.Collections; 35 import java.util.List; 36 37 /** 38 * A {@link Discovery} subclass managing a list of {@link DiscoveredPrinter} objects, persisted 39 * between application sessions 40 */ 41 public abstract class SavedDiscovery extends Discovery { 42 private static final String TAG = SavedDiscovery.class.getSimpleName(); 43 private static final boolean DEBUG = false; 44 45 // manualPrinters for backward-compatibility 46 private static final List<String> PRINTER_LIST_NAMES = Arrays.asList("printers", 47 "manualPrinters"); 48 49 private final File mCacheFile; 50 private final List<DiscoveredPrinter> mSavedPrinters; 51 SavedDiscovery(BuiltInPrintService printService)52 SavedDiscovery(BuiltInPrintService printService) { 53 super(printService); 54 mCacheFile = new File(printService.getCacheDir(), getClass().getSimpleName() + ".json"); 55 mSavedPrinters = load(); 56 } 57 58 /** 59 * Add a persisted printer, returning true if a change occurred 60 */ addSavedPrinter(DiscoveredPrinter printer)61 boolean addSavedPrinter(DiscoveredPrinter printer) { 62 Uri printerUri = printer.getUri(); 63 DiscoveredPrinter old = find(printerUri); 64 if (old != null) { 65 if (printer.equals(old)) { 66 return false; 67 } 68 mSavedPrinters.remove(old); 69 } 70 71 mSavedPrinters.add(0, printer); 72 save(); 73 return true; 74 } 75 76 /** 77 * Return a DiscoveredPrinter having the specified URI, or null 78 */ find(Uri printerUri)79 private DiscoveredPrinter find(Uri printerUri) { 80 for (DiscoveredPrinter printer : mSavedPrinters) { 81 if (printer.getUri().equals(printerUri)) { 82 return printer; 83 } 84 } 85 return null; 86 } 87 88 /** 89 * Remove the first saved printer matching the supplied printer path 90 */ 91 @Override removeSavedPrinter(Uri printerPath)92 public void removeSavedPrinter(Uri printerPath) { 93 for (DiscoveredPrinter printer : mSavedPrinters) { 94 if (printer.path.equals(printerPath)) { 95 mSavedPrinters.remove(printer); 96 save(); 97 return; 98 } 99 } 100 } 101 102 /** 103 * Return a non-modifiable list of saved printers 104 */ 105 @Override getSavedPrinters()106 public List<DiscoveredPrinter> getSavedPrinters() { 107 return Collections.unmodifiableList(mSavedPrinters); 108 } 109 110 /** 111 * Load the list from storage, or return an empty list 112 */ load()113 private List<DiscoveredPrinter> load() { 114 List<DiscoveredPrinter> printers = new ArrayList<>(); 115 if (!mCacheFile.exists()) { 116 return printers; 117 } 118 119 try (JsonReader reader = new JsonReader(new BufferedReader(new FileReader(mCacheFile)))) { 120 reader.beginObject(); 121 while (reader.hasNext()) { 122 String itemName = reader.nextName(); 123 if (PRINTER_LIST_NAMES.contains(itemName)) { 124 reader.beginArray(); 125 while (reader.hasNext()) { 126 printers.add(new DiscoveredPrinter(reader)); 127 } 128 reader.endArray(); 129 } 130 } 131 reader.endObject(); 132 } catch (IllegalStateException | IOException ignored) { 133 Log.w(TAG, "Error while loading from " + mCacheFile, ignored); 134 } 135 if (DEBUG) Log.d(TAG, "Loaded size=" + printers.size() + " from " + mCacheFile); 136 return printers; 137 } 138 139 /** 140 * Save the current list to storage 141 */ save()142 private void save() { 143 if (mCacheFile.exists()) { 144 mCacheFile.delete(); 145 } 146 147 try (JsonWriter writer = new JsonWriter(new BufferedWriter(new FileWriter(mCacheFile)))) { 148 writer.beginObject(); 149 writer.name(PRINTER_LIST_NAMES.get(0)); 150 writer.beginArray(); 151 for (DiscoveredPrinter printer : mSavedPrinters) { 152 printer.write(writer); 153 } 154 writer.endArray(); 155 writer.endObject(); 156 } catch (NullPointerException | IOException e) { 157 Log.w(TAG, "Error while storing to " + mCacheFile, e); 158 } 159 } 160 } 161