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 
23 import androidx.annotation.VisibleForTesting;
24 
25 import java.util.Map;
26 
27 /**
28  * Class providing core logic for backup and restore of DocumentsUI preferences.
29  */
30 final class PrefsBackupHelper {
31 
32     private SharedPreferences mDefaultPreferences;
33 
34     @VisibleForTesting
PrefsBackupHelper(SharedPreferences overridePreferences)35     PrefsBackupHelper(SharedPreferences overridePreferences) {
36         mDefaultPreferences = overridePreferences;
37     }
38 
PrefsBackupHelper(Context context)39     PrefsBackupHelper(Context context) {
40         mDefaultPreferences = PreferenceManager.getDefaultSharedPreferences(context);
41     }
42 
43     /**
44      * Loads all applicable preferences to supplied backup file.
45      */
getBackupPreferences(SharedPreferences prefs)46     void getBackupPreferences(SharedPreferences prefs) {
47         Editor editor = prefs.edit();
48         editor.clear();
49 
50         copyMatchingPreferences(mDefaultPreferences, editor);
51         editor.apply();
52     }
53 
54     /**
55      * Restores all applicable preferences from the supplied preferences file.
56      */
putBackupPreferences(SharedPreferences prefs)57     void putBackupPreferences(SharedPreferences prefs) {
58         Editor editor = mDefaultPreferences.edit();
59 
60         copyMatchingPreferences(prefs, editor);
61         editor.apply();
62     }
63 
copyMatchingPreferences(SharedPreferences source, Editor destination)64     private void copyMatchingPreferences(SharedPreferences source, Editor destination) {
65         for (Map.Entry<String, ?> preference : source.getAll().entrySet()) {
66             if (LocalPreferences.shouldBackup(preference.getKey())) {
67                 setPreference(destination, preference);
68             }
69         }
70     }
71 
72     @SuppressWarnings("unchecked")
73     @VisibleForTesting
setPreference(Editor target, final Map.Entry<String, ?> preference)74     void setPreference(Editor target, final Map.Entry<String, ?> preference) {
75         final String key = preference.getKey();
76         final Object value = preference.getValue();
77         // Only handle already know types.
78         if (value instanceof Integer) {
79             target.putInt(key, (Integer) value);
80         } else if (value instanceof Boolean) {
81             target.putBoolean(key, (Boolean) value);
82         } else {
83             throw new IllegalArgumentException("DocumentsUI backup: invalid preference "
84                     + (value == null ? null : value.getClass()));
85         }
86     }
87 }
88