AppLocalesStorageHelper.java
/*
* Copyright 2023 The Android Open Source Project
*
* 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 androidx.core.app;
import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP_PREFIX;
import android.content.Context;
import android.util.Log;
import android.util.Xml;
import androidx.annotation.NonNull;
import androidx.annotation.RestrictTo;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlSerializer;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
/**
* Helper class to manage storage of locales in app's persistent files.
*/
@RestrictTo(LIBRARY_GROUP_PREFIX)
public class AppLocalesStorageHelper {
static final String APPLICATION_LOCALES_RECORD_FILE =
"androidx.appcompat.app.AppCompatDelegate.application_locales_record_file";
static final String LOCALE_RECORD_ATTRIBUTE_TAG = "application_locales";
static final String LOCALE_RECORD_FILE_TAG = "locales";
static final String TAG = "AppLocalesStorageHelper";
static final boolean DEBUG = false;
private static final Object sAppLocaleStorageSync = new Object();
private AppLocalesStorageHelper() {}
/**
* Returns app locales after reading from storage, fetched using the application context.
*/
@NonNull
public static String readLocales(@NonNull Context context) {
synchronized (sAppLocaleStorageSync) {
String appLocales = "";
FileInputStream fis;
try {
fis = context.openFileInput(APPLICATION_LOCALES_RECORD_FILE);
} catch (FileNotFoundException fnfe) {
if (DEBUG) {
Log.d(TAG, "Reading app Locales : Locales record file not found: "
+ APPLICATION_LOCALES_RECORD_FILE);
}
return appLocales;
}
try {
XmlPullParser parser = Xml.newPullParser();
parser.setInput(fis, "UTF-8");
int type;
int outerDepth = parser.getDepth();
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
String tagName = parser.getName();
if (tagName.equals(LOCALE_RECORD_FILE_TAG)) {
appLocales = parser.getAttributeValue(/*namespace= */ null,
LOCALE_RECORD_ATTRIBUTE_TAG);
break;
}
}
} catch (XmlPullParserException | IOException e) {
Log.w(TAG,
"Reading app Locales : Unable to parse through file :"
+ APPLICATION_LOCALES_RECORD_FILE);
} finally {
if (fis != null) {
try {
fis.close();
} catch (IOException e) {
/* ignore */
}
}
}
if (!appLocales.isEmpty()) {
if (DEBUG) {
Log.d(TAG,
"Reading app Locales : Locales read from file: "
+ APPLICATION_LOCALES_RECORD_FILE + " ," + " appLocales: "
+ appLocales);
}
} else {
context.deleteFile(APPLICATION_LOCALES_RECORD_FILE);
}
return appLocales;
}
}
/**
* Stores the provided locales in internal app file, using the application context.
*/
public static void persistLocales(@NonNull Context context, @NonNull String locales) {
synchronized (sAppLocaleStorageSync) {
if (locales.equals("")) {
context.deleteFile(APPLICATION_LOCALES_RECORD_FILE);
return;
}
FileOutputStream fos;
try {
fos = context.openFileOutput(APPLICATION_LOCALES_RECORD_FILE, Context.MODE_PRIVATE);
} catch (FileNotFoundException fnfe) {
Log.w(TAG, String.format("Storing App Locales : FileNotFoundException: Cannot open "
+ "file %s for writing ", APPLICATION_LOCALES_RECORD_FILE));
return;
}
XmlSerializer serializer = Xml.newSerializer();
try {
serializer.setOutput(fos, /* encoding= */ null);
serializer.startDocument("UTF-8", true);
serializer.startTag(/* namespace= */ null, LOCALE_RECORD_FILE_TAG);
serializer.attribute(/* namespace= */ null, LOCALE_RECORD_ATTRIBUTE_TAG, locales);
serializer.endTag(/* namespace= */ null, LOCALE_RECORD_FILE_TAG);
serializer.endDocument();
if (DEBUG) {
Log.d(TAG, "Storing App Locales : app-locales: "
+ locales + " persisted successfully.");
}
} catch (Exception e) {
Log.w(TAG, "Storing App Locales : Failed to persist app-locales in storage ",
e);
} finally {
if (fos != null) {
try {
fos.close();
} catch (IOException e) {
/* ignore */
}
}
}
}
}
}