a SharedPreferences replacement for Android with multiprocess support
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README.md

Tray - a SharedPreferences replacement for Android

Build Status License

If you have read the documentation of the SharedPreferences you might have seen one of these warnings:

Note: This class does not support use across multiple processes.

Google even deprecated the multiprocess support because it never worked relieable

Tray is this mentioned explicit cross-process data management approach powered by a ContentProvider. Tray also provides an advanced API which makes it super easy to access and maintain your data with upgrade and migrate mechanisms. Welcome to SharedPreferences 2.0 aka Tray.

Features

Usage

Simple tutorial how to use Tray in your project instead of the SharedPreferences

Save and read preferences

// create a preference accessor. This is for global app preferences.
final AppPreferences appPreferences = new AppPreferences(getContext()); // this Preference comes for free from the library
// save a key value pair
appPreferences.put("key", "lorem ipsum");

// read the value for your key. the second parameter is a fallback (optional otherwise throws)
final String value = appPreferences.getString("key", "default");
Log.v(TAG, "value: " + value); // value: lorem ipsum

// read a key that isn't saved. returns the default (or throws without default)
final String defaultValue = appPreferences.getString("key2", "default");
Log.v(TAG, "value: " + defaultValue); // value: default

No Editor, no commit() or apply() 😉

Create your own preference module

It's recommended to bundle preferences in groups, so called modules instead of putting everything in one global module. If you were using SharedPreferences before, you might have used different files to group your preferences. Extending the TrayModulePreferences and put all Keys inside this class is a recommended way to keep your code clean.

// create a preference accessor for a module
public class MyModulePreference extends TrayPreferences {

    public static String KEY_IS_FIRST_LAUNCH = "first_launch";

    public MyModulePreference(final Context context) {
        super(context, "myModule", 1);
    }
}
// accessing the preferences for my own module
final MyModulePreference myModulePreference = new MyModulePreference(getContext());
myModulePreference.put(MyModulePreference.KEY_IS_FIRST_LAUNCH, false);

See the sample project for more

Like the Android SQLiteOpenHelper a TrayPreference lets you implement methods to handle versioning.

public class MyModulePreference extends TrayPreferences {

    public MyModulePreference(final Context context) {
        super(context, "myModule", 1);
    }

    @Override
    protected void onCreate(final int initialVersion) {
        super.onCreate(initialVersion);
    }

    @Override
    protected void onUpgrade(final int oldVersion, final int newVersion) {
        super.onUpgrade(oldVersion, newVersion);
    }

    @Override
    protected void onDowngrade(final int oldVersion, final int newVersion) {
        super.onDowngrade(oldVersion, newVersion);
    }
}

// TOOD add clear sample

Migrate from SharedPreferences to Tray

To migrate values from SharedPreferences you have to create you own preference module. This module will be now store all of your SharedPreferences values.

public class ImportPreferences extends TrayPreferences {

    // The SharedPreferences name
    private static final String SHARED_PREFERENCES_FILE_NAME = "PREF_NAME";
    
    // The key inside the SHARED_PREFERENCES_NAME
    private static final String KEY_FIRST_LAUNCH = "KEY_FIRST_LAUNCH";
    
    // The new key for this module
    private static final String KEY_FIRST_LAUNCH_TRAY = "KEY_FIRST_LAUNCH_TRAY";
    
    public ImportPreferences(@NonNull Context context) {
        super(context, "myImportModule", 1);
    }    
    
    // Called only once when the module was created
    @Override
    protected void onCreate(int initialVersion) {
        super.onCreate(initialVersion);
            
        // Create a SharedPreferencesImport object
        SharedPreferencesImport importPref = 
            new SharedPreferencesImport(getContext(), 
                SHARED_PREFERENCES_FILE_NAME, KEY_FIRST_LAUNCH, KEY_FIRST_LAUNCH_TRAY);
            
        // Finally migrate it
        migrate(importPref);
    }
}

Getting Started Download

Add Tray to your project

Tray is available via jcenter

dependencies {
    compile 'net.grandcentrix.tray:tray:0.12.0'
}

More on the ContentProvider configuration can be found in the wiki

Project state

Tray is currently in active development by grandcentrix. We decided to go open source after reaching 100% test coverage. grandcentrix uses Tray in production in two apps without problems.

You can follow the development in the develop branch.

Testcoverage 100%

Tray has 100% test coverage and we'll try to keep it at that level for stable releases.

You can run the coverage report with ./gradlew createDebugCoverageReport. You'll find the output in library/build/outputs/coverage/debug/index.html which looks like this:

coverage report

You can check the coverage report at codecov.io

Those ~170 tests will help us indicate bugs in the future before we publish them. Don't think the code is 100% bug free based on the test coverage.

Build state

Build Status

codecov.io

ContentProvider is overkill

At first, it was the simplest way to use IPC with Binder to solve the multiprocess problem. Using the ContentProvider with a database turned out to be very handy when it comes to save metadata. We thought about replacing the database with the real SharedPreferences to boost the performance (the SharedPreferences do not access the disk for every read/write action which causes the multiprocess problem btw) but the metadata seemed to be more valuable to us. see more informations

If you have found a better solution implement the TrayStorage and contribute to this project! We would appreciate it.

That said, yes the performance isn't as good as the SharedPreferences. But the performance is good enough to save/access single key value pairs synchron. If you want to save more you should think about a simple database.

Missing Features

Tray is ready to use without showblockers! But here are some nice to have features for the future:

  • Reactive wrapper to observe values
  • no support to save Set<String>. Is someone using this?
  • more metadata fields: (i.e. app version code/name)

Roadmap

  • performance tests
  • memory cache for based on contentobservers
  • prevent app crashes due to database errors
  • rx wrapper for changes
  • save additional data types (Set<String>, byte[])

Versions

Version 0.11.1 07.02.17
  • preference key cannot be empty #84
  • clearBut(TrayPreference) -> clearBut(AbstractTrayPreference) #89
Version 0.11.0 07.09.16
  • all accessor methods return boolean indicating the success of i.e. put, remove. They will never again throw an error. #69
  • new contains() method #74
Version 0.10.0 31.05.16
  • All features and changes of the 1.0.0-rc preview builds
  • #65 Fix deletion of non string migrated shared preferences.
Version 1.0.0 preview - postponed until the memory cache is ready
1.0.0-rc3 05.11.15
  • hotfix for listener on Android 6.0 which has caused a infinity loop #55
  • the sample project includes now a way to test the multi process support compared to the SharedPreferences
  • removed unnecessary write operation for every version check #54
1.0.0-rc2 24.09.15
  • added logging for all data changing methods. Enable via adb shell setprop log.tag.Tray VERBOSE
1.0.0-rc1 21.09.15
  • Android M Auto Backup feature support (see the Documentation)
    • split up database for user and device specific data (device specific data can now be excluded from the auto backup)
    • TrayPreferences has now an optional 3. constructor parameter TrayStorage.Type, USER or DEVICE indicating the internal database (required for Android M Auto Backup). Default is USER
  • New methods and changes
    • PreferenceAccessor#wipe() clears the preference data and it's internal data (version)
    • TrayPreferences#annexModule(String name) imports a module by name and wipes it afterwards. This allows renaming of preferences without losing data
    • AbstractTrayPreference#annex(ModularizedStorage<TrayItem>) allows a storage to import another storage, wipes the imported afterwards
    • Preference #onCreate(...) and #onUpgrade(...) aren't abstract anymore because they don't require an implementation
  • Deprecations (will be removed soon)
    • TrayAppPreferences is now deprecated. Use AppPreferences instead (renaming)
    • TrayModulePreferences is now deprecated. Use TrayPreferences instead to extend from for your own Preferences
  • Internal structure
    • new package structure. merged packages accessor, migration and storage into core
    • package provider contains a TrayStorage implementation with a ContentProvider. Is easy exchangeable with another TrayStorage implementation
    • ModularizedTrayPreference is now called AbstractTrayPreference
    • ModularizedStorage was renamed to TrayStorage
Version 0.9.2 02.06.15
  • getContext() is working in TrayModulePreference#onCreate
Version 0.9.1 18.05.15
  • saving null with mPref.put(KEY, null) works now
  • access to preference with throwing methods instead of default value (throws ItemNotFoundException). Example: mPref.getString(KEY); instead of mPref.getString(KEY, "defaultValue");
  • WrongTypeException when accessing a preference with a different type and the data isn't parsable. Float (10.1f) -> String works, String ("10.1") -> Float works, String ("test") -> Float throws!
  • javadoc in now included in aar
Version 0.9 27.04.15
  • initial public release
Version 0.2 - 0.8
  • Refactoring
  • 100% Testing
  • Bugfixing
Version 0.1 17.09.14
  • first working prototype

Contributors

License

Copyright 2015 grandcentrix GmbH

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.