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      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
     34     PrefsBackupHelper(SharedPreferences overridePreferences) {
     35         mDefaultPreferences = overridePreferences;
     36     }
     37 
     38     PrefsBackupHelper(Context context) {
     39         mDefaultPreferences = PreferenceManager.getDefaultSharedPreferences(context);
     40     }
     41 
     42     /**
     43      * Loads all applicable preferences to supplied backup file.
     44      */
     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      */
     56     void putBackupPreferences(SharedPreferences prefs) {
     57         Editor editor = mDefaultPreferences.edit();
     58 
     59         copyMatchingPreferences(prefs, editor);
     60         editor.apply();
     61     }
     62 
     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
     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