Java Question Third-party VPN library import error

laomms · Nov 9, 2020

I made a VirtualHosts.aar library from https://github.com/x-falcon/Virtual-Hosts, and use #AdditionalJar: VirtualHosts.aar import to b4a project.

in java project there are some codes like this :

Java:

package com.github.xfalcon.vhosts.vservice;

import ...


public class VhostsService extends VpnService {
    ...
      
     public static void startVService(Context context, int method) {
        ...
    }

in b4a I write:

B4X:

'#AdditionalRes: ..\resource
#AdditionalJar: VirtualHosts.aar

Sub Activity_Create(FirstTime As Boolean)
    Dim pm As B4XPagesManager
    pm.Initialize(Activity)
  
    'Dim ctxt As JavaObject
    'ctxt.InitializeContext
    Dim fb As JavaObject
    fb.InitializeNewInstance("com.github.xfalcon.vhosts.vservice.startVService",Array("23.101.130.247 microsoft.gointeract.io", 2))
  
    Activity.LoadLayout("mainpage")
    WebView1.LoadUrl("https://microsoft.gointeract.io/interact/index?interaction=1461173234028-3884f8602eccbe259104553afa8415434b4581-05d1&accountId=microsoft&appkey=196de13c-e946-4531-98f6-2719ec8405ce&Language=Italian&CountryCode=IT&CountryLanguage=IT&Click%20To%20Call%20Caller%20Id=+31641190689&startedFromSmsToken=QCYw2pA&sessionID=188781095&token=wXVhvi")

End Sub

It abnormal in : java.lang.ClassNotFoundException: com.github.xfalcon$vhosts$vservice$startVService , likes can not find the aar library.

agraham · Nov 9, 2020

startVService
is a method so you can't create an instance of it. You need an instance of
com.github.xfalcon.vhosts.vservice.VhostsService
and then call startVService by RunMethod. Even then it may not work, but you can only try.

laomms · Nov 10, 2020

thanks agraham, I change the code as below:

B4X:

    Dim ctxt As JavaObject
    ctxt.InitializeContext
    Dim fb As JavaObject
    Dim O As JavaObject=fb.InitializeNewInstance("com.github.xfalcon.vhosts.vservice.VhostsService",Null)
    O.RunMethod ("startVService",Array(ctxt, 2))

the errors occurred with Method: startVService not found in: com.github.xfalcon.vhosts.vservice.VhostsService

stevel05 · Nov 10, 2020

Check the code you compiled the library from, it appears that there is no method startVService in the VhostsService class.

laomms · Nov 10, 2020

how to call this function: startVService

agraham · Nov 10, 2020

Ah! I just noticed it's a static method. You don't call it on an instance,

Accessing third party Jar with #Additionaljar and JavaObject - Picasso

The #AdditionalJar module attribute (introduced in B4A v3.80) allows us to reference external jars. With the help of JavaObject it is now possible to integrate third party jars without a wrapper. This solution is good for "simple" libraries. If the API is complicated with many interfaces then...

www.b4x.com

stevel05 · Nov 10, 2020

I tried running it on a static object, still wouldn't find it.

DonManfred · Nov 10, 2020

stevel05 said:
still wouldn't find it.

probably the needed manifestchanged are not applied?
A service from a AAR must be added to the manifest; it does not happen automatically.

Virtual-Hosts/app/src/main/AndroidManifest.xml at main · x-falcon/Virtual-Hosts

hosts for android,implement by vpn mode,supports wildcard DNS records - x-falcon/Virtual-Hosts

github.com

agraham · Nov 10, 2020

Steve is correct. I've looked in the aar and there is no static startVService in the VhostsService class

DonManfred · Nov 10, 2020

agraham said:
Steve is correct. I've looked in the aar and there is no static startVService in the VhostsService class

Virtual-Hosts/app/src/main/java/com/github/xfalcon/vhosts/vservice/VhostsService.java at main · x-falcon/Virtual-Hosts

hosts for android,implement by vpn mode,supports wildcard DNS records - x-falcon/Virtual-Hosts

github.com

Line 215

agraham · Nov 10, 2020

DonManfred said:
Line 215

What do you mean? I've taken the aar file in the first post attachment apart and as you can see from the image above there is no startVService method. If you compare my image and the source file there is other stuff missing as well. Perhaps he's got the wrong file.

DonManfred · Nov 10, 2020

agraham said:
What do you mean?

Did you checked the link in my post and had a look at line 215 of the link?

agraham said:
I've taken the aar file in the first post attachment

I did visit the githubpage and had a look at the Source.

Check line 215 of this link

Virtual-Hosts/app/src/main/java/com/github/xfalcon/vhosts/vservice/VhostsService.java at main · x-falcon/Virtual-Hosts

hosts for android,implement by vpn mode,supports wildcard DNS records - x-falcon/Virtual-Hosts

github.com

laomms · Nov 11, 2020

under android studio, I can normal import this aar, and use the startVService function normal:

agraham · Nov 11, 2020

Ah! The penny's dropped, the problem is obvious but I overlooked it. The code in the aar is obfuscated! Look at my screenshot above.

laomms · Nov 12, 2020

I found two similar github projects: https://github.com/nICEnnnnnnnLee/PureHost and https://github.com/lmgy/Redirect , It seems much simpler than this project, I will try to compile to aar and then try to import.

stevel05 · Nov 12, 2020

If you try a new one or the same one, you will need to turn off obfuscation.

laomms · Nov 12, 2020

yes, I have comment out ‘minifyEnabled true’ and ‘shrinkResources true’ when compiling aar library file , It seems enable shrinkResources when compiling the com.android.library file will report an exception.

stevel05 · Nov 12, 2020

It's a long time since I used android studio, and that was only playing with it. I don't know if there is more than one tool that could be used, but Proguard seems to be referenced in the threads I've looked at.

info in this link may help you turn it off. https://stackoverflow.com/questions/57156648/how-to-add-code-obfuscation-for-my-android-application

laomms · Nov 12, 2020

thanks stevel05, after comment out all obfuscation items in build.gradle, it can be called successfully. But there are a lot of things to be resolved. I can only give up it.
Hope B4X will support the VpnService library in the future or publish some similar libraries.

laomms · Nov 17, 2020

Change to SLC ways, I try use SLC wrapper it to b4a library, it can compiled successfully, but when import to B4A, Prompt the following error:

B4X:

java.lang.RuntimeException: Unable to start activity ComponentInfo{b4a.example/top.nicelee.purehost.MainActivity}: android.content.res.Resources$NotFoundException: Resource ID #0x7f0b001c

Java Question Third-party VPN library import error

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