I understand that there is no Application Level Scope available to be able to define shared logic/data, and that each activity is essentially a stand alone application tied together by the manifest...
BUT I have a group of user access permissions that I am getting via a web service call and do not want to make this call in every activities onCreate().
I am using SharedPreferences in the application, but since the permissions are not intended to be editable by the user, the flat file exposure on android devices feels like an insecure way to handle this.
I do need to re-request this info if the application is restarted, so I believe the least expensive would be to store it in a variable.
I am aware of IntentExtras but we are talking about a Settings "Object", not a primitive type.
right way to handle this situation?
You can actually create an "Application" class that can be used to essentially create Application wide settings.
Just create a new class and extend Application, then set any class members and appropriate getter/setter methods and you can access them throughout your application.
You then need to update your manifest as follows:
<application android:icon="#drawable/logo"
android:label="#string/app_name"
android:name=".application.CustomApplication">
Then in any activity you can access it as follows:
CustomApplication app = ((CustomApplication)getApplication());
I think that using shared preferences is fairly secure. Only advanced users with root, custom roms and hacking knowledge would be able to take a chance at it! (I'm not even sure that this would be possible).
Besides SharedPreferences, you could also implement a custom Application object and keep your permissions there.
Anyway, as a developer I think that it's much more likely to be hacked somewhere within the request I do to get the user permissions (use https, etc) and my application being decompiled.
Related
I have an interesting use case where I need to pass certain data to my application so that it can be used in its "attachBaseContext" method.
I know that typically, the proper way to pass data to an application is to use an intent and pass the data through to an "activity" but this is too late in my application's life cycle. I need the data in my application so that I can use it to setup the environment prior to any android components running (e.g. Activities, Services, ContentProviders, etc.).
At the moment, I use a very hack-ish approach where I write the data to my application's internal storage and then read it in my "attachBaseContext". I am hoping there is a better way though to do this as this doesn't seem very safe/clean.
Any ideas?
First time asking on stackoverflow here !
Okay so here's the context. I'm doing an android application, and I'm trying to implement something like a plug-in framework.
My main app's MainActivity's purpose is to manage and launch/show Fragments.
Each of my plug-in will contain (at least) a Fragment and it's layout.
Thus, the idea is to fetch the fragment and put it inside my main app's MainActivity, from it.
So I decided to put my Fragments/Plug-ins into different apps and give all my plug-ins and main app the same user_id. This way all of them are in the same process, and even if they appear in the phone's Application Manager, only the main app is launchable and visible in the Application Browser (which is great).
But here's my problem... How do I get access to my plug-ins Fragments ?
I thought I could fetch some class through the PackageManager and use relfexion to use my fragment, but apparently you can't (or I didn't find how).
I considered binding Services together on each end (Application - Plug-in) but I have no guarantee that the services will bind together. Especially since each app have the same copy of the service, aka not the same Service.
Maybe by using a common .jar to make sure the Services are the same, and thus pass an instance of my Fragment to the main app (yes an instance would suffice).
Or make a CustomClassLoader (but then I might need advice on how to load classes from my other app, because I don't know how to do that...)
I've been running in circles in my head and on the net to find a solution...
To make things clear:
How do i fetch the classe (CustomClassLoader) or an instance (via binding or maybe sharedPreference or wiriting my instance in a file and read it in the main ?) of another app, considering they share the same user_id and thus are in the same process ?
Just because apps share the same user_id this does not imply they are running in the same process. They may and propably have been started by the same process. Sharing resources amongst processes is commonly known as IPC.
AIDL , the android Interface Definition language is a way for implementing IPC. Still this will not allow you retrieve objects from a different application directly but the possibility to invoke methods on remote objects.
But your problem description to me seems more like accessing objects of an jar at runtime in an application. This could be done via classloading.
So your app could retrieve a jar from a Server and load your fragments from it. The definitions of the fragments than would be runtime updateable if you define your fragments completely by code.
In my android backup, i want to backup the SharedPreferences and some Data stored in a SQL database.
Is it possible to register two backupAgents in the android manifest (one for each) or do i have to implement my own custom manager which stores both?
If its possible
<application
android:backupAgent=".SharedPrefBackupAgentHelper"
android:backupAgent=".SQLBackupAgent"
/>
I'm no expert at this, as I just started using the Data Backup API.
But, I believe if you declare an attribute twice, it will only use one of them.
So in this case, you would have only actually registered .SQLBackupAgent
What I'd do is have one BackupAgent class, for example, .MultiBackupAgent.
Then that class would initialize and call the methods of your two backup agents.
No, you can't have more than one designated backup agent class for your application. You just need to write your agent's onBackup() / onRestore() logic to handle all the various kinds of data that you need to save & restore. Some people choose to do this by deriving their agent class from BackupAgentHelper and then writing separate BackupHelper subclasses for the different kinds of data that they want to store, for example. That is not necessary, of course; you can just do it all explicitly in your agent class -- it's basically just a matter of figuring out what will work best for you.
I'm trying to understand how the Application class.
I've noticed that need to declare it in <application> manifest within the tag and then can access the variables in other classes as they were global variables. And even out of the application the value of these varieties do not change.
However, if you unplug the phone, the next time you turn it on and start applying the value of the variables returned to its initial state.
I wonder if you can maintain the state of variables when we turned off the phone and reconnect it?
Application data is available as long as your application is "active". When the OS decides to terminate it to clear memory, so goes your application data (you typically don't control when this happens, as per the mobile development good practices: the OS decides on its own), and it's not persisted for the next time you start the app. So anything you store in the Application should be stored again each time the app is started.
It should be used to keep short-term data available to you. A good use case is when you need to access a complex data structure from multiple activities: it's not possible to use bundles for that. You can generate your complex data structure in your start activity, store it in the application, and then retrieve it in any other application that may need it.
But you should not use it for long-term persistent data. For that, the best is to use a SQLite database.
I'm not sure I fully understand what you mean, but it seems like you want to use Shared Preferences.
try this Question: Android - How Do I Set A Preference In Code
I have a Weather app with four Activities. The main/launcher activity is 'invisible' using...
android:theme="#android:style/Theme.Translucent.NoTitleBar"`
...and is simply used to do a few checks (whether this is a new install, whether a network connection is available etc) before firing off one of the other Activities. The other Activities are UI-oriented - two simply display weather data pulled from a website and the third to provide a location 'picker' so the user can choose which area to show the weather for.
However, all four activities make use of a WeatherHelper object which basically does everything from checking for available SD card storage to maintaining preferences and pulling/formatting website pages.
So, my question(s)...what is the best way to have one instance of WeatherHelper which can be used by multiple activities and where/how are best to create it in my case?
I've been an OO programmer for a lot of years but I'm very new to Android and the design concepts - I've read a lot on the Android Developers site over the past weeks but I've stalled trying to decide on this.
Any ideas gratefully received.
I would store shared information in you Application object. Subclass this and add any extra initialization and data there. You can get your application using getApplication() from your activity, which you can cast to your specialized version and access the shared data.
I would also avoid launching the special startup activity if possible and do the work in your Application's onCreate() override.
Well, your question has been answered, but it seems like it would be much simpler to instantiate your WeatherHelper object in the onCreate() of the Activity that has the launcher intent, and make the WeatherHelper static.