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 package com.android.documentsui.prefs;
17 
18 import android.content.Context;
19 import android.content.SharedPreferences;
20 import android.content.SharedPreferences.Editor;
21 import android.preference.PreferenceManager;
22 import android.support.annotation.VisibleForTesting;
23 
24 import java.util.Map;
25 
26 /**
27  * Class providing core logic for backup and restore of DocumentsUI preferences.
28  */
29 final class PrefsBackupHelper {
30 
31     private SharedPreferences mDefaultPreferences;
32 
33     @VisibleForTesting
PrefsBackupHelper(SharedPreferences overridePreferences)34     PrefsBackupHelper(SharedPreferences overridePreferences) {
35         mDefaultPreferences = overridePreferences;
36     }
37 
PrefsBackupHelper(Context context)38     PrefsBackupHelper(Context context) {
39         mDefaultPreferences = PreferenceManager.getDefaultSharedPreferences(context);
40     }
41 
42     /**
43      * Loads all applicable preferences to supplied backup file.
44      */
getBackupPreferences(SharedPreferences prefs)45     void getBackupPreferences(SharedPreferences prefs) {
46         Editor editor = prefs.edit();
47         editor.clear();
48 
49         copyMatchingPreferences(mDefaultPreferences, editor);
50         editor.apply();
51     }
52 
53     /**
54      * Restores all applicable preferences from the supplied preferences file.
55      */
putBackupPreferences(SharedPreferences prefs)56     void putBackupPreferences(SharedPreferences prefs) {
57         Editor editor = mDefaultPreferences.edit();
58 
59         copyMatchingPreferences(prefs, editor);
60         editor.apply();
61     }
62 
copyMatchingPreferences(SharedPreferences source, Editor destination)63     private void copyMatchingPreferences(SharedPreferences source, Editor destination) {
64         for (Map.Entry<String, ?> preference : source.getAll().entrySet()) {
65             if (Preferences.shouldBackup(preference.getKey())) {
66                 setPreference(destination, preference);
67             }
68         }
69     }
70 
71     @SuppressWarnings("unchecked")
72     @VisibleForTesting
setPreference(Editor target, final Map.Entry<String, ?> preference)73     void setPreference(Editor target, final Map.Entry<String, ?> preference) {
74         final String key = preference.getKey();
75         final Object value = preference.getValue();
76         // Only handle already know types.
77         if (value instanceof Integer) {
78             target.putInt(key, (Integer) value);
79         } else if (value instanceof Boolean) {
80             target.putBoolean(key, (Boolean) value);
81         } else {
82             throw new IllegalArgumentException("DocumentsUI backup: invalid preference "
83                     + (value == null ? null : value.getClass()));
84         }
85     }
86 }
87