Is is possible to create a new APK by overloading/overriding and existing APK.
Say, we have WhatsApp messenger. Now if I want to show a notification like, "Person X is online now.", in notification area, it is not possible using the existing WhatsApp messenger. So, I'd like to develop a new custom messenger, which uses all the functionality of WhatsApp messenger, with some of my custom code. Just like importing JARs, can we import APK...??
This seems like using another persons work, but just from learning point of view, I'd like to know the possibilities. As of now, lets leave all the, security, vulnerability.
In a nutshell, no.
APKs are not like Jar files such that you can simply import them into your app. They also contain other resources like the XML and assets. The code is kept in a classes.dex file, which is generated from the Jar file of the app code.
Moreover, each app runs in its own DVM, and is sandboxed to prevent this kind of interaction between apps. You cannot simply use WhatsApp's code in your own app as a third party apps.
There are however two ways to achieve what you want.
If the app you are targeting provides an API by means of content providers, or even web services that you can use to access their data and events like users coming online. WhatsApp does not offer any such API
You decompile the target app, and insert your own code to do what you want. This can be very hard because most popular apps, like WhatsApp, obfuscate their code making it hard to decipher (but not impossible). Additionally, WhatsApp encrypts most of its data like messages, contacts, chat threads etc using AES, which adds an additional layer to bypass in some places. Oh, and it also violates several IP and copyright laws if you do this.
Yes and No.
There are a couple of ways for an app - a standalone one - to share its information with other apps. One is through the use of a content provider, the other through custom broadcasts.
If, say, WhatsApp has documented its app and was built such that you can build on it further, you can catch those broadcasts and listen to those providers such that your app can also react upon the changes made in WhatsApp.
you can create a config.properties file and insert it in Asset folder in your wattsup messenger assuming you have the source code,
Now you will have to configure your custom application to write that changes in this file, however you can change these data in several ways such as webservices that allows you to modify that data in that file through them .
ok with the above scenario, you can make the changes,but your application will never update that changes coz your dealing with an APK not a code,therefore you will have to re-generate the APK again so it will take the latest changes .
for an automated APK generating you can use ANT tools, by placing a build.xml file in your wattsp sources
code you can run that script which ant release that will generate the new APK with the latest code
as you said these are possibilities still but in my opinion in the end you cant use the APK as a library
Related
Context: I have two apps, both signed with the same signature. The first app has data stored in internal storage that I would like to migrate to the second app.
Question: How can I access the data in the first app from the second app? The Android documentation makes reference to "signature permissions" (https://developer.android.com/guide/topics/permissions/overview#signature and https://developer.android.com/training/articles/security-tips#StoringData) and hints that it is possible to share data between apps with the same signature, but I cannot find clear guidelines about how to do this.
It seems like it might be possible by creating a content provider? Or is it possible to directly access the files, since I understand from the docs that they will be running with the same user / same process?
Ideally this process can happen with minimal intervention from the user, and can all happen from the second app (e.g. the second app can recognize that the first app is installed, prompt the user to migrate, and then read the data from the first app and move it to the second). It would be even better if it was possible to move the files (rather than copy) because we potentially have a lot of data and the user may not have enough disk space to copy the data.
It seems like it might be possible by creating a content provider?
Yes. You can create a signature-level permission and use that to protect access to any of the standard IPC options in Android, including ContentProvider and Service.
Or is it possible to directly access the files, since I understand from the docs that they will be running with the same user / same process?
No, two apps signed by the same signing key to not run as the same user, let alone in the same process. android:sharedUserId has the apps run as the same user. This was never a great idea, is deprecated, and is likely to go away soon.
It would be even better if it was possible to move the files (rather than copy) because we potentially have a lot of data and the user may not have enough disk space to copy the data.
That suggests that having two apps is a bug, not a feature, from the standpoint of the user. The closest you will be able to do to a "move" operation is "delete-after-copy", so plan your copies to be as granular as possible so you can delete as you go.
Some relevant background:
My application is a Java app compiled into a .exe via JSmooth. The anticipated user base would likely be a few hundred users, but could grow well beyond that, as it's a community specific application.
How it works:
2 .jar files, one that preforms initial checks, another with the meat of the application.
Ideally, the init jar displays the splash, checks the version in desktop.txt against server.txt, if they differ, it prompts the user to update.
What I need to figure out:
1) What is a cheap, scalable hosting service that I could use as the file host for updates?
2) How can I create an "updater" to actually preform the jar replacement? My current solution is simply writing an updater in Java, but I was hoping for something like the installers people are more familiar with.
All of the research I've done has resulted in lackluster results, as 99% of hosting searches result in site hosting results. I just need an update repository with reasonable security. i.e., decent DDoS resistance and not left wide open to the Internet.
Edit: formatting
Easy to do and very foolish cheap with Amazon S3 or Joyent Manta as both support time-limited signed URLs and headers (which can contain a SHA-1 of the file) to check to see if the update is needed before downloading
On startup your app would check the update URL to see if it has changed. If it has changed, download the JARs. Do this before the app loads classes from those JARs. Updating the updater itself will be trickier so consider that an update might need a new update URL to prevent expiry.
I have written an android application. I would like to be able to customize the app programmatically. For example, change logos/titles within the application.
Assume I have a simple web server that displays a form with fields to input text, upload images etc. Upon submission of this form, I would like to generate an apk file available for download for the user.
Is there a way to script eclipse to achieve this? Is that even where I should be looking? If anyone has done something like this, (or have some ideas), please let me know!
Thanks
Is there a way to script eclipse to achieve this?
Possibly, but I doubt it.
Is that even where I should be looking?
Use Ant. Make a copy of some master project, make your adjustments from the entered data, and run the appropriate ant tasks (e.g., ant release build) to create the APK.
We have put together a system that creates multiple, customised APKs from a single body of source code. The system is not in a state where we can make it available (although we may open source it at some point) but the general structure is described here.
Having said that, the system you describe in your question is much more dynamic than what we need. We only need to create a few (~10) different variants. It strikes me that what you're trying to do would be better solved by having a single APK together with a configuration file. Your webserver would generate the configuration file, not the APK.
I have an SQLite database stored in the assets resources of one application used to load UI and other stuff into the app, mainly just holding text nothing out of the ordinary. I want to be able to get a writable version of this database so I can modify it from another application.
Example:
First application is on the market with limited number of enabled features. User gets to a certain point where they need to buy extra content to do more stuff in the app. The original app has these features but they are not enabled in the app using the database. I want the user then to download a second app from the market which is just used to change one field in the database from disabled to enabled thus unlocking the new features.
I have an idea I may need to use content providers but my understanding is once created they are accessible to all applications. I need it, for piracy reasons I guess, to only be able to communicate with apps signed off by my key.
Thanks
Sam,
I understand what you intend to do, but you are going about it the wrong way. Your 'Unlock App' would not be able to modify the Database in the assets folder of your 'Free App'. That's just general android security model stuff.
You may want to look at this question: How can I use the paid version of my app as a "key" to the free version?
It describes how you can create a 'Unlock App' on the market to unlock features of your 'Free app' without needing to actually modify any of the original data in the 'Free App'.
Good luck
I'm working on an app that is meant to be used by fans of a sport team. In the future, I expect to use the same app but for any different team. So, what changes would be the colors, team logo, app name and the like.
So, is there any technique that allows me to build binaries for different teams without having duplicated resources?
Probably the best way is to depart from the default build system. That typically means writing custom Ant scripts (or you could use some kind of preparatory script that manipulates the resources prior to invoking the default build).
I've previously sketched an outline of how I achieved something similar.
Is it possible to have one binary that contains all the resources and have the user select which team they want from the app itself? Then the app can load whichever resources it needs.
There may be a better way to do this, but here goes:
Build your app for the first team and make all logos / team names / styles / etc resources. Then just write yourself a script that allows you to delete all the items in the res/ folder of your project and replace them with different items. If you are smart, then most of the string's like team names are included in the logos, so all your script has to do is to delete the old ones and copy in the new ones from some other location on your hard drive.
The worst part about this is that you will have to define android-type file for the styles. It might be good to have your script take as parameters a team primary & secondary color, and actually generate all the android-type style files.
Again, there might be a better way, I am just saying that this way could be a solution.
I think build your application which will load the image , colour information from internet / your server. then,
1) ask user for team name which they are following and download image,color information from internet/server and store it as local. don't download next time.
2) attach any global id with each build which will download the image,color information from server first time user installs the application.