使用内部存储在Android应用程序之间共享大量数据？

Question

Background: we are porting an enterprise system to have android clients. The architecture for windows and html is based around a core library that does the hard business logic but no user interaction at all, and we use programs or single page web apps to provide the user interface and simply call the core API library to actually do stuff.

The "core" is implemented as a shared library on windows and built into each app. If we mirror this and use a java library, we need to share files using external storage, which is a not permitted as data needs to be reasonably secure. (Nb data is binary data, not Sql database, in case that is relevant)

So we thought about using a bound service, and using intents, content provider etc, but it seems (from googling) we must then distribute the background service separately the user interface app, but this seems terrible experience for new users. However, a bound service seems ideal from all other angles.

We also cannot guarantee which apps a user might download, we will have at least 10 individual apps all doing logically different things, but referencing similar data.

In brief:

• lots of individual apps all wanting access to same data
• no control over which apps are downloaded
• using external data is not permitted as data should be semi secure
• using sqllite might not work as data is long binary chunks ( eg 3Mb plus ). (Ref: How to share data across a group of applications in Android )
• some data files are big and do not want every app to download a private copy
• some data changes dynamically, say every 15min
• core business logic is big and complex, cannot be distributed in source form, lib/jar ok though.
• the windows solutions all use network IO to an application server, but we want to avoid as much network traffic as possible by storing data locally.

How can we bundle a bound service in each and every user interface app we distribute? Or is there a different way to approach this whole design?

Answer 1

I think that there is a few number of options that you can explore:

1) I never have done this before though this seems possible as Android is package based. First you need to use the same main package across all your apps though each app must be in a separated sub package, eg : main -> au.com.myapp.main and the app actually have it's first screen on app1 -> au.com.myapp.main.app1 . Create on your main app a method(s) that will look for those extra packages (within your project), as it find something you create a trigger that will display a item on the menu. Each app should have the same main packages and main activity, as it will be responsible for enable the user have access to the others and all of them can share the same preferences, files folders and Database. When installing the same packages should be overrides though those different ones should keep intact. You should have all the 'main' classes for each app, not the real main one declared on your manifest (that will be quite big depending on the amount of activities in all your apps) with those packages.

2) You can using Spongy Castle, create a shared zone (folder) where you create the DB and write your settings or files, encrypting everything with a key (strong one or using RSA) that might be made by the user or provided once for your company at the very first run. You must decide how to handle this.

3) You also can use the share id in all your apps and each app before run perform look up for all packages (it's possible to do) to know and if and what packages exist to check if there is a DB with data in that package.

4) Not really nice though create a background service that keep updated all tables in all apps (sharing id or using content provider), you can user AlarmManager to trigger it in intervals rather keep it on at all times and you have all apps.

My last project had a similar requirement though as the user had to login to do anything, I opted for the option 3 and each data pertinent exclusively to each app went the app DB. I hope this helps.