Hi i am looking into an android development , as we all know when we build the project it makes an APK that is the whole program. but is it possible to make a an android project / APK that would be able to use external files to include more info into the project.
like say for example i have a list commands or functions in my list , but i dont want it to be added into my APK build , is it possible to use it externally?
i was curious because something like COC and other games after downloading it , then downloads extra data from the net , more into updates for the whole game.
how is this possible or is it possible to do , and use functions or source codes externally and not include it into the APK , and also the proper usage of it
Any Android App can connect to the Internet and save downloaded data files to use as they need, without requiring to include them inside the APK. Indeed, for many games (and other Apps having large data sets), it's a sensible option.
There are a couple of things to be aware of:
Android restricts where (on the filesystem) you can save files. And no matter where you save the files, the user can delete them at any
time. Your App should be able to cope with this.
The files should only ever be data files - not executable code. Attempting to
execute downloaded files is likely to put your users at risk
(depending on the permissions your App was installed with) and is also likely to get your App marked as malware.
You should read the Android documentation on Data Storage to learn a bit more about it.
Related
I am developing an Android application that has a NDK .so file which I need to iterate on and fix + improve.
The current workflow has me having to generate a APK and install it every iteration which updates a whole plethora of non NDK elements in the process really slowing things down.
The question is how could I access the installation folder of my own APK? I have both a rooted and unrooted device.
Is there some change I could make to install the app in an unprotected location for development purposes even. The installation data is my own application after all so feels like should be a way...
Help greatly appreciated :)
EDIT1:
I found Unity3D has some sort of patching mode, maybe this is a sign that with the correct ADB commands it may be possible... https://docs.unity3d.com/Manual/android-AppPatching.html
EDIT2: I found the location of the .so I am building in... checked on unrooted device and don't have permission.
If your app is not a native-only app (has a Java/Kotlin part) then your so library should be loaded at the moment using a call to System.loadlibrary(..).
What is interesting on this method is, that calls to this method are ignored if the library to be loaded has already been loaded. So if you modify the Java code of the development build of your app to manually load your library before the original loadLibrary call is executed you can end up with a different library loaded.
The only problem is that System.loadLibrary(..) does not accept a file-name or path as argument. But using System.load(..) which uses a full path as argument you should be able to specify a full path to a file e.g. in the app's data directory. That way you can replace the library as often as you want and then just restart the app to load the updated library.
Android introduced the Multiple Users feature in 4.2 (Jelly Bean MR1) and its documentation states:
From your app’s point of view, each user is running on a completely separate device.
And here is a quote from the Environment.getExternalsStorageDirectory() and getExternalStoragePublicDirectory() methods doc:
On devices with multiple users (as described by UserManager), each user has their own isolated external storage. Applications only have access to the external storage for the user they're running as.
Could it be true that there really is no reliable way to communicate data between users on a single device without using the network as mediator? I'm looking for solutions that don't rely on quirks of how the device's file system is laid out by a manufacturer. Also, for security, the sharing should be internal to my app.
Even if file sharing is indeed impossible, is communication via intents somehow possible?
There are use cases for this. Use Case 1: let's say I'm writing an input method app that requires a 100MB dictionary file. I'd like to code things so that if User A downloads this file, then User B can access it also without needing to re-download. Use Case 2: let's say I'm writing a fun Leave My Wife a Note app that allows User A to type messages that will appear next time User B logs in (without using the network).
This thread on a separate site proposes a solution, but their method seems undocumented and possibly unreliable. And there are a few other SO questions that have a title similar to this one but are actually discussing different topics.
OBB Folder (/sdcard/Android/obb) is used to share files and folder between the multi users. But OBB folder not shown in my second user (One plus 5 mobile). So I have tried to create an OBB folder in Android folder (/sdcard/Android/) in second user and "BOOM" it worked. Now i am able to access the shared files in second user. Try this trick if OBB folder not shown in your second user.
OBB files (stored in /sdcard/Android/obb) and used as expansion files in Google Play are shared between all users by design, as they are fairly large. If you Input method uses expansion files, the downloaded data will be shared automatically. You can send broadcasts to other users but that requires the INTERACT_ACROSS_USERS permission, which is reserved for system applications.
I also had the same question, and have tried various approaches such as using /sdcard/Android/obb but it does not work in Android 10. So I followed below approach, and I am able to copy files seamlessly between users.
Login to the User from where you would like to copy files from (lets call U1)
Run FTP Server using any application of choice like MiXplorer / ES Explorer etc... Note down the details of the port#, username, password etc... and point it to /sdcard
Switch user, to where you want to copy files to (lets call U2)
Install the FTP browser. If you use MiXplorer / ES Explorer, they will allow you to add a FTP share
Use ftp://localhost:2121 assuming the port is 2121, if not change it accordingly and add the FTP share
Open the FTP share and you can see all the files & folders of U1 here
Copy across to your heart's content !
I'm looking to packing a large sqlite database with an android app, about 200-300MB. From what I've read, my options are putting it in the assets folder, and coping it out at runtime, resulting in duplicate data, or downloading the database from the web at runtime. I don't want to create a webserver for this app, so I was thinking of creating a seperate app that just installs the database to get around the data duplication problem.
All of those are pretty crummy, and I was wondering if there is a better solution?
First, I don't think you are allowed to put a 200-300MB database in your assets folder and distribute it as a single apk, since the hard limit for an apk file size is (as per google's documentation) 50 MB and I doubt that your db will compress that far.. Google introduced the "APK expansion files" for packaging large files with your apk. You can read all about those here: http://developer.android.com/google/play/expansion-files.html
I think (but I have no experience with expansion files myself) that this will not fix the issue you mentioned about having to deal with duplicate data because of the requirement to copy out your database file, but at least this will help you in the sense that you won't have to host your database file on your own webserver. I quickly scanned the documentation on the link I gave above and it clearly states that you should NOT throw away the expansion files when you are done with them, so no help on that part.
Of course, for the "setting up your own webserver part": I wouldn't even bother setting up my own webserver. There are plenty of parties out there that provide you some file hosting service. Probably you will have to pay for the bandwidth, but hey.. if people download your db file a lot, that also means that your app is doing well ;-)
I test of apk expansion files. I created a test app with a 100 MB sqlite database, uploaded the apk and database to the play store. I then downloaded the app onto the phone, the database was downloaded at the same time. The database was automatically renamed and placed in the publicly accessible directory:
/storage/sdcard0/Android/obb/com.example.app/main.1.com.example.app.obb
The app was able to open the database without any problems, but required external read and write permissions. The new and original database are bit for bit, the same. This appears to be the best solution for my use case.
A few issues, the new android developer console does not support uploading expansion files, so the old one needs to be used. Google only allows 2 expansion files, so that may be an issue for some use cases. Google say that you must not rename or delete the file, and that your app must be able to download the file from Google itself if it wasn't automatically installed.
I'm working on a platform=app for games and I want the user to be able to choose games like some kind of an add on, then it will download some file (a game) which my app knows how to read and work with.
Basically, what I want is to build a market without apk files.
Or to generate a new kind of apk files.
I hope you can understand my question..
The way I do it is to simply send a level to the client using the network connection.
My maps look like: [[0,1,2],[0,-1-1]...] which can be nicely compressed.
Even a big level doesn't take more than a few seconds to download.
You just need to generate your own 'level' code reader.
the way snesdroid works is it will play emulator files on the sd card, not sure if you could code the app to download files directly to the sdcard in a specific folder then have the app rescan that directory to refresh the levels.
How can I instruct Eclipse to copy a file from my Android solution to an emulator, as part of Run/Debug? I have a small database, stored in Assets, that needs to accompany the application. Thus far I have simply copied the file myself using DDMS but would prefer to have it automatically included. The project properties allow me to specify some aspects of the build, e.g. the build order and which libraries should be included, but I don't see anything about simply copying a file.
Is the file in your "res/assets" folder not available using the AssetManager class during testing versus during testing or when installed via a signed apk?
I use a large file that I store in "res/raw" in one of my games, I am able to access this file during testing with eclipse without a problem just using the normal calls to context.getResources().openRawResource()
Deploying databases with your application it a reoccurring topic over in the android-developers Google group here is a post with a few thoughts on the matter.
Good luck.