SharedPreferencesUtils.java

/*
 * Copyright (C) 2011 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.android.utils;

import android.content.Context;
import android.content.SharedPreferences;
import android.content.res.Resources;
import android.preference.PreferenceManager;
import android.support.v4.content.ContextCompat;
import android.support.v4.os.BuildCompat;

/**
 * Utility methods for interacting with {@link SharedPreferences} objects.
 */
public class SharedPreferencesUtils {
    /**
     * Returns the value of an integer preference stored as a string. This is
     * necessary when using a {@link android.preference.ListPreference} to
     * manage an integer preference, since the entries must be {@link String}
     * values.
     *
     * @param prefs Shared preferences from which to obtain the value.
     * @param res Resources from which to obtain the key and default value.
     * @param keyResId Resource identifier for the key.
     * @param defaultResId Resource identifier for the default value.
     * @return The preference value, or the default value if not set.
     */
    public static int getIntFromStringPref(
            SharedPreferences prefs, Resources res, int keyResId, int defaultResId) {
        final String strPref = prefs.getString(
                res.getString(keyResId), res.getString(defaultResId));
        return Integer.parseInt(strPref);
    }

    /**
     * Returns the value of a floating point preference stored as a string. This
     * is necessary when using a {@link android.preference.ListPreference} to
     * manage a floating point preference, since the entries must be
     * {@link String} values.
     *
     * @param prefs Shared preferences from which to obtain the value.
     * @param res Resources from which to obtain the key and default value.
     * @param keyResId Resource identifier for the key.
     * @param defaultResId Resource identifier for the default value.
     * @return The preference value, or the default value if not set.
     */
    public static float getFloatFromStringPref(
            SharedPreferences prefs, Resources res, int keyResId, int defaultResId) {
        final String strPref = prefs.getString(
                res.getString(keyResId), res.getString(defaultResId));
        return Float.parseFloat(strPref);
    }

    /**
     * Returns the value of a string preference.
     *
     * @param prefs Shared preferences from which to obtain the value.
     * @param res Resources from which to obtain the key and default value.
     * @param keyResId Resource identifier for the key.
     * @param defaultResId Resource identifier for the default value.
     * @return The preference value, or the default value if not set.
     */
    public static String getStringPref(SharedPreferences prefs, Resources res, int keyResId,
            int defaultResId) {
        return prefs.getString(res.getString(keyResId),
                ((defaultResId == 0) ? null : res.getString(defaultResId)));
    }

    /**
     * Returns the value of a boolean preference.
     *
     * @param prefs Shared preferences from which to obtain the value.
     * @param res Resources from which to obtain the key and default value.
     * @param keyResId Resource identifier for the key.
     * @param defaultResId Resource identifier for the default value.
     * @return The preference value, or the default value if not set.
     */
    public static boolean getBooleanPref(SharedPreferences prefs, Resources res, int keyResId,
            int defaultResId) {
        return prefs.getBoolean(res.getString(keyResId), res.getBoolean(defaultResId));
    }

    /**
     * Stores the value of a boolean preference.
     *
     * @param prefs Shared preferences from which to obtain the value.
     * @param res Resources from which to obtain the key and default value.
     * @param keyResId Resource identifier for the key.
     * @param value The value to store.
     */
    public static void putBooleanPref(
            SharedPreferences prefs, Resources res, int keyResId, boolean value) {
        storeBooleanAsync(prefs, res.getString(keyResId), value);
    }

    /**
     * Stores the value of a boolean preference async.
     *
     * @param prefs Shared preferences from which to obtain the value.
     * @param key The pref key
     * @param value The value to store.
     */
    public static void storeBooleanAsync(SharedPreferences prefs, String key, boolean value) {
        SharedPreferences.Editor editor = prefs.edit();
        editor.putBoolean(key, value);
        editor.apply();
    }

    /**
     * Gets the appropriate SharedPreferences depending on the device capabilities.
     * On systems that support device-protected storage (Android N or later with compatible device),
     * returns SharedPreferences backed by device-protected storage.
     * Otherwise, returns SharedPreferences backed by a standard credential-protected storage
     * context.
     */
    public static SharedPreferences getSharedPreferences(Context context) {
        Context deContext = ContextCompat.createDeviceProtectedStorageContext(context);
        if (deContext != null) {
            return PreferenceManager.getDefaultSharedPreferences(deContext);
        } else {
            return PreferenceManager.getDefaultSharedPreferences(context);
        }
    }

    /**
     * Move existing preferences file from credential protected storage to device protected storage.
     * This is used to migrate data between storage locations after an Android upgrade from
     * Build.VERSION < N to Build.VERSION >= N.
     */
    public static void migrateSharedPreferences(Context context) {
        if (BuildCompat.isAtLeastN()) {
            Context deContext = ContextCompat.createDeviceProtectedStorageContext(context);
            deContext.moveSharedPreferencesFrom(context,
                    PreferenceManager.getDefaultSharedPreferencesName(context));
        }
    }
}