how to use android plugin sdk in unity?

For example, i have LiveKit SDK for Android and i need to integrate this plugin into my Unity project for android devices.

I have searched for many tutorials, but none of them had good explanation how to implement this whole SDK to my project and properly use it

In addition, i just took livekit.aar file from .gradle folder and put it in unity project Then, I coded it like that

private void Start() {
    AndroidJavaClass liveKit = new AndroidJavaClass("io.livekit.android.LiveKit");
    devInf.text = "Found LiveKit Class";
    AndroidJavaClass unityPlayer = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
    AndroidJavaObject currentActivity = unityPlayer.GetStatic<AndroidJavaObject>("currentActivity");
    AndroidJavaObject applicationContext = currentActivity.Call<AndroidJavaObject>("getApplicationContext");

    AndroidJavaObject room = liveKit.CallStatic<AndroidJavaObject>("create", applicationContext);

    token = PlayerPrefs.GetString("stream-token", "");
    Debug.LogWarning(token);

    StartCoroutine(ConnectCoroutine(room, url, token));
    //Invoke("CreateRoomWithDelay", 3f);
}

IEnumerator ConnectCoroutine(AndroidJavaObject room, string url, string token) {
    devInf.text = "Starting Connection";
    yield return room.Call<IEnumerator>("connect", url, token);

    AndroidJavaObject localParticipant = room.Call<AndroidJavaObject>("localParticipant");

    if (localParticipant != null) {
        AndroidJavaObject audioTrack = localParticipant.Call<AndroidJavaObject>("createAudioTrack");
        AndroidJavaObject videoTrack = localParticipant.Call<AndroidJavaObject>("createVideoTrack");

        localParticipant.Call("publishAudioTrack", audioTrack);
        localParticipant.Call("publishVideoTrack", videoTrack);

        localParticipant.Call("setCameraEnabled", true); 
        localParticipant.Call("setMicrophoneEnabled", true); 
    }
}

this is how i realized livekit in android studio

fun startStream() {
    val cfgData = getCfgData.getData()
    viewModelScope.launch {

        if (token != null) {
            room.connect(STREAM_URL, token)
            val localParticipant = room.localParticipant
            val videoTrack = localParticipant.createVideoTrack(
                "video",
                LocalVideoTrackOptions(position = CameraPosition.BACK)
            )
            localParticipant.publishVideoTrack(videoTrack)

            val audioTrack = localParticipant.createAudioTrack(
                "audio",
                LocalAudioTrackOptions()
            )
            localParticipant.publishAudioTrack(audioTrack)

            localParticipant.setCameraEnabled(true)
            localParticipant.setMicrophoneEnabled(true)
        }
    }
}

Solution

LiveKit has unity plugin so you shouldn't need to install Android SDK separately.

But if you want to know how to add android libraries to the Unity, here are the steps:

Adding Android library from Maven repository:

Download and install External Dependency Manager for Unity. https://github.com/googlesamples/unity-jar-resolver (there is external-dependency-manager-latest.unitypackage)
In your Assets directory, create "Editor" directory
Inside "Editor" create XML file and name it as you like, e.g. MyDependencies.xml

In XML add:

<?xml version="1.0" encoding="UTF-8" ?> 
<dependencies>
  <androidPackages>
    <repositories>
      <repository>https://repo1.maven.org/maven2</repository>
      <repository>https://jitpack.io</repository>
    </repositories>
    <androidPackage spec="io.livekit:livekit-android:2.0.1"/>
  </androidPackages>
</dependencies>

I would recommend enabling Custom Main Gradle Template and Custom Gradle Properties Templete in Edit > Project Setting > Player > Android > Publishing Settings. When templates are enabled, External Dependency Manager will use Gradle to resolve dependencies, which works a lot better than Dependency manager's own implementation.
Then proceed to Assets > External Dependency Manager > Android Resolver > Resolve
If you have enabled minification in Publishing Settings and are working with added Android library from C#, you may face class not found/defined errors. In that case you will need to enable Custom Proguard File and add:
```
-keep class io.livekit.** { public *; }
```

Adding Android library as .aar archive:

Copy .aar file to the Assets/Plugins/Android directory
If needed, add custom Proguard rules to avoid code obfuscation.

Note that many Android libraries have transitive dependencies, which means that also dependencies' aar files needs to be added.