Add registerWith method for FlutterCallkeepPlugin, fix #4.

Author: cloudwebrtc

android/src/main/java/com/github/cloudwebrtc/flutter_callkeep/FlutterCallkeepPlugin.java

@@ -1,14 +1,18 @@
 package com.github.cloudwebrtc.flutter_callkeep;
 
+import android.app.Activity;
+import android.content.Context;
 import androidx.annotation.NonNull;
 
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
 import io.flutter.embedding.engine.plugins.activity.ActivityAware;
 import io.flutter.embedding.engine.plugins.activity.ActivityPluginBinding;
+import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.MethodCall;
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.MethodChannel.MethodCallHandler;
 import io.flutter.plugin.common.MethodChannel.Result;
+import io.flutter.plugin.common.PluginRegistry.Registrar;
 import io.wazo.callkeep.CallKeepModule;
 
 /** FlutterCallkeepPlugin */
@@ -20,11 +24,44 @@ public class FlutterCallkeepPlugin implements FlutterPlugin, MethodCallHandler,
   private MethodChannel channel;
   private CallKeepModule callKeep;
 
+  /**
+   * Plugin registration.
+   */
+  public static void registerWith(Registrar registrar) {
+    final FlutterCallkeepPlugin plugin = new FlutterCallkeepPlugin();
+
+    plugin.startListening(registrar.context(), registrar.messenger());
+
+    if (registrar.activeContext() instanceof Activity) {
+      plugin.setActivity((Activity) registrar.activeContext());
+    }
+
+    registrar.addViewDestroyListener(view -> {
+      plugin.stopListening();
+      return false;
+    });
+  }
+
+  private void setActivity(@NonNull Activity activity) {
+    callKeep.setActivity(activity);
+  }
+
+  private void startListening(final Context context, BinaryMessenger messenger) {
+    channel = new MethodChannel(messenger, "FlutterCallKeep.Method");
+    channel.setMethodCallHandler(this);
+    callKeep = new CallKeepModule(context, messenger);
+  }
+
+  private void stopListening() {
+    channel.setMethodCallHandler(null);
+    channel = null;
+    callKeep.dispose();
+    callKeep = null;
+  }
+
   @Override
   public void onAttachedToEngine(@NonNull FlutterPluginBinding flutterPluginBinding) {
-    channel = new MethodChannel(flutterPluginBinding.getBinaryMessenger(), "FlutterCallKeep.Method");
-    channel.setMethodCallHandler(this);
-    callKeep = new CallKeepModule(flutterPluginBinding.getApplicationContext(), flutterPluginBinding);
+    startListening(flutterPluginBinding.getApplicationContext(), flutterPluginBinding.getBinaryMessenger());
   }
 
   @Override
@@ -36,7 +73,7 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull Result result) {
 
   @Override
   public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {
-    channel.setMethodCallHandler(null);
+    stopListening();
   }
 
   @Override

android/src/main/java/io/wazo/callkeep/CallKeepModule.java

@@ -54,6 +54,7 @@
 import java.util.Map;
 
 import io.flutter.embedding.engine.plugins.FlutterPlugin;
+import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.EventChannel;
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.MethodCall;
@@ -87,15 +88,20 @@ public class CallKeepModule {
     Activity _currentActivity = null;
     MethodChannel _eventChannel;
 
-    public CallKeepModule(Context context, FlutterPlugin.FlutterPluginBinding binding) {
+    public CallKeepModule(Context context, BinaryMessenger messenger) {
         this._context = context;
-        this._eventChannel = new MethodChannel(binding.getBinaryMessenger(), "FlutterCallKeep.Event");
+        this._eventChannel = new MethodChannel(messenger, "FlutterCallKeep.Event");
     }
 
     public void setActivity(Activity activity) {
         this._currentActivity = activity;
     }
 
+    public void dispose(){
+        LocalBroadcastManager.getInstance(this._context).unregisterReceiver(voiceBroadcastReceiver);
+        VoiceConnectionService.setPhoneAccountHandle(null);
+    }
+
     public boolean HandleMethodCall(@NonNull MethodCall call, @NonNull Result result) {
         switch(call.method) {
             case "setup": {