I want to share data between different Android applications. On iOS applications I use the Keychain with an accessGroup property so the data is only accessible from my applications plus the data remains even if I delete all applications.
What mechanism can I use to do the same on Android?
Thanks in advance,
You can use ContentProviders. Here is a good tutorial on ContentProviders. And this post specifically tells about data sharing using it.
ContentProviders are the way to go on Android for sharing data between apps.
From the Android tutorials:
Content providers manage access to a structured set of data. They encapsulate the data, and provide mechanisms for defining data security. Content providers are the standard interface that connects data in one process with code running in another process.
Use ContentProviders to do that.
Related
i'm beginner in android development, need help regarding ContentProvider.
public class My Application extends ContentProvider {}
A ContentProvider manages access to a structured set of data. It encapsulates the data and provide mechanisms for defining data security. ContentProvider is the standard interface that connects data in one process with code running in another process.
Kindly refer following links,
https://developer.android.com/guide/topics/providers/content-provider-creating.html
and
https://www.tutorialspoint.com/android/android_content_providers.htm
A content provider component supplies data from one application to others on request. one application cannot directly access (read/write) other application's data. Every application has its own id data directory and own protected memory area.
Content provider is the best way to share data across applications. Content provider is a set of data wrapped up in a custom API to read and write. Applications/Processes have to register themselves as a provider of data.
In simple language you can say content provider is a shared database which expose his properties and on there behalf of them other application can access and store the data as per the implementation privilege
Content providers can help an application manage access to data stored by itself, stored by other apps, and provide a way to share data with other apps. They encapsulate the data, and provide mechanisms for defining data security. Content providers are the standard interface that connects data in one process with code running in another process. Implementing a content provider has many advantages. Most importantly you can configure a content provider to allow other applications to securely access and modify your app data.
It is not that they are used only to share data with other applications. You may still use them because they provide a nice abstraction, but you don’t have to necessarily share data with other apps. This abstraction allows you to make modifications to your application data storage implementation without affecting other existing applications that rely on access to your data
You can get more info from the documentation.
ContentProvider is mainly used for access data from one application to another application.
For example by using ContentProvider we can get phone contacts,call log from phone to our own application in android.we can also access data which are stored in (sqlite)databases.
Everyone,I was looking at android source.But I could not find something valuable for me.Actually,I want to know whether ContentProvider is worked like AIDL.You know ,AIDL can achieve the communication between two independence application.
So, I just want to see how does the ContentProvider work internally.
From ContentProvider Source code
Content providers are one of the primary building blocks of Android
applications, providing content to applications. They encapsulate data
and provide it to applications through the single ContentResolver
interface. A content provider is only required if you need to share
data between multiple applications. For example, the contacts data is
used by multiple applications and must be stored in a content
provider. If you don't need to share data amongst multiple
applications you can use a database directly via
android.database.sqlite.SQLiteDatabase.
According to this and to the information in the link I sent you, ContentProvider isn't using AIDL... It is using the ContentResolver interface.
Content Providers use IPC Binders internally. "In fact, Intents and ContentProvider are just a higher-level abstraction of Binder"
So I come mostly from a web background and I'm trying to learn the architecture of android apps. Trying to grasp a proper understanding of content providers.
What I think I'm understanding is that content providers are pretty much your middle man between the activity/services and your data (DAO of sort). I also think that content provider are also to provide other applications access to your data (almost like a web service?)
What I'm not really getting is, what if you did not need this data exposed to other applications? Do I need to bother with content providers and all the uri defining etc? If not, is there a name for this ... pattern? (or lack of) Or am I better off just using ContentProviders and just accept the added benefit of exposing this data to other apps?
I know eventually I will want to sync data between the app and a external database. I saw a google IO presentation supporting the pattern of using a content provider for RESTful communication. But for the time being, I'm just trying to get comfortable with basic static data. Then hopefully swap it out to data from a REST service down the line once I get it.
Hope I'm not completely off here. Thanks.
Although it says that content providers are nice for sharing content they also give you a couple of other things free!
The best thing about content providers is that the system handles the threading issues for you :) when I ported my app over to Honeycomb i got lots of database errors (mind you ones that couldn't previously exist in gingerbread) I wasn't handling the access on different threads properly.
I quickly put a content provider on top of my database and well.. never looked back in that regards, it seems much easier once you've setup your content provider the code throughout the rest of the app is much nicer and you don't have to worry about concurrency
As written in the specs, and as you mentioned :
Content providers store and retrieve data and make it accessible to all applications. They're the only way to share data across applications; there's no common storage area that all Android packages can access.
So if the data you are storing should not be accessible by other applications there is no need to bother with ContentProviders. As you can see on Android Data Storage there are several ways in which you could store your data.
My opinion is that in your case, for usage of REST Services, and data that is not to be shared with other application you should use SQLiteDatabase. You can find a good example SQLiteDatabase example here.
I understand that Content Providers are made to allow publicly sharing data between applications. However, I'm wondering if anyone has thoughts about making a Content Provider to use just within your own app. Would there be any advantages to doing this? Any disadvantages?
In the past I've just implemented the SQliteOpenHelper to access data from my database, but I'm considering creating a Content Provider. I feel like the URI approach to requesting data is clear and concise. On the other hand, will using a Content Provider just for my application be redundant ( since within it I will have a SQliteOpenHelper class ) and more work than I need?
I would argue it is definitely a good idea to use a ContentProvider even if you don't intend to make it public.
It's good practice to provide the extra level of abstraction over your data to make it easier to change internally. What if you decide to change the underlying database structure at a later time? If you use a ContentProvider you can contain all the structural changes within it, where as if you don't use one, you are forced to change all areas of the code that are affected by the structural changes. Besides, it's nice to be able to re-use the same standard API for accessing data rather than littering your code with low-level access to the database.
Also, there is always the chance that you might want to expose your data in the future. If you don't use a ContentProvider up front, it will be much harder to retrofit it in at a later date.
Then, there's the other parts of the Android where ContentProvider's are required/recommended such as when using SyncAdapters and if you want an App Widget that involves data access for instance.
In summary, there is very little overhead involved in writing a ContentProvider up front (once you have learned the API which is a good idea anyway) so it makes sense to do so, even for private data.
If you are not planning to share data, don't think about Content Providers. They are powerful but hard to write and it will be just silly to implement them if you are going to use them internally.
However, I'm wondering if anyone has thoughts about making a Content Provider to use just within your own app.
Of course... for instance, for an old TODO list app I wrote, I had to write a content provider to allow other apps retrieve and access the tasks states. It was part of the requirements, but more than that it made sense and made the app nicer.
Take a look at the MOTODEV Studio for Eclipse. It is a development environment that extends Eclipse. They have a tool where you can automatically generate a content provider for a database. If a content provider makes it easier to access your data and it doesn't have a significant impact on performance go ahead and use it. In most scenarios this will be the case.
In short,Content Providers helps in managing your data effectively. I would suggest to use them for the following reasons.
It acts as an abstraction layer between your UI and database. You can implement data validation in ContentProviders to validate the data entered by the user. It also lets you to modify the structure of the database without touching the UI and other parts.
They play along nicely with other android framework classes like SyncAdapter. For eg., you can automatically refresh a list, when a value in a database changes using ContentProviders along with CursorLoader. Without ContentProviders you have to implement a lot of functionalities like these on your own.
We can safely expose our private data to other apps. Using ContentProviders will allow us to share our data easily and safely with other apps.
So even if you don't need any of these functionalities now, you might need them in future and its good to go the extra mile and implement them right now.
I agree ContentProviders are a little difficult to grasp but they are definitely helpful, even if you want to use them internally for you own app. The best thing about it is that you can customize the contentproviders for suitable URIs.
Here's a scenario where you may have 5 tables in your database, but you need to join a few of them in certain orders before using them. And make a content URI for each of these joins. You could then each use these URIs as a table :)
I suggest you go ahead with Content Provider, you'll be amazed to see how powerful it is.
In my view point, the content-provider comes with plenty of advantages leave alone just sharing data with other apps. If you need to synchronize with the server using a Sync-Adapter, use google cloud messaging, auto update the UI when the underlying data in the DB changes using Loaders, implement search, use widgets... then the content provider is for you.
I prefer you follow the guideline on because one day you may need to implement some of the above features attached to the content-provider
By the way, you can quickly build you database and CP in less than 5 minutes using content provider generator
As said in documentation:
Creating a Content provider
You don't need a provider to use an SQLite database if the use is
entirely within your own application.
So why bother developing this overhead? You want easier and faster development, right? So one layer of abstraction (SQLiteOpenHelper descendent) is enough.
See Occam's Razor
Do not make an entities without very good reason.
Using a Content Provider can help in an additional level of abstraction - Putting it within your own application make add a significant development time to your project. However if you are using it to share data, application settings or configurations across multiple applications then the Content Provider is your choice.
Watch your security levels and I would recommend using SQLcipher to encrypt data-at-reset (DAR) if your Content Provider is writing to SQLite. (I've used a content provider in a few solutions and provided the ability to take a live "snap shot" of the operational values for debugging and testing.)
Do not use content provider if do not wish to share data with other apps. Use simple sqlitedatabase to perform database operations. Be careful while using content providers for storing confidential data because your confidential information may be accessed by other apps
I am developing an application that involves some sensitive user information. I retrieve this information via a private web API. I am trying to determine the best way to get this data into my app. Right now I'm exploring creating a content provider that can do so; my hesitation is in making it secure. I want this data to be usable only by my application. Ideally, no other apps would even know it exists.
Do you have any pointers or advice on how to do this effectively and securely?
Any info on content providers who's data source is a remote OAuth'd API?
Thanks!
Edit: I say content provider, but if that isn't the best way to do what I need, by all means let me know what else to look into.
Try android:exported="false" in your manifest.
Why even consider a ContentProvider? As far as I know ContentProviders are meant to share data with other applications. I would suggest writing a utility class to interface with your storage of the sensitive data, be it SQLite or whatever.
-Dan