added javascript interface to listen post messages

Author: erdemyerebasmaz

android/src/main/java/com/flutter_webview_plugin/WebviewManager.java

@@ -10,6 +10,7 @@
 import android.view.View;
 import android.view.ViewGroup;
 import android.webkit.CookieManager;
+import android.webkit.JavascriptInterface;
 import android.webkit.ValueCallback;
 import android.webkit.WebChromeClient;
 import android.webkit.WebSettings;
@@ -171,6 +172,7 @@ public boolean onShowFileChooser(
                 return true;
             }
         });
+        webView.addJavascriptInterface(new WebAppInterface(), "Android");
     }
 
     private void clearCookies() {
@@ -339,4 +341,13 @@ void stopLoading(MethodCall call, MethodChannel.Result result){
             webView.stopLoading();
         }
     }
+
+    public class WebAppInterface {
+        @JavascriptInterface
+        public void getPostMessage(String value){
+            Map<String, Object> orderMap = new HashMap<>();
+            orderMap.put("order", value);
+            FlutterWebviewPlugin.channel.invokeMethod("onOrderRequest", orderMap);
+        }
+    }
 }

lib/src/base.dart

@@ -29,6 +29,7 @@ class FlutterWebviewPlugin {
   final _onScrollXChanged = StreamController<double>.broadcast();
   final _onScrollYChanged = StreamController<double>.broadcast();
   final _onHttpError = StreamController<WebViewHttpError>.broadcast();
+  final _lightningLinkStream = StreamController<String>.broadcast();
 
   Future<Null> _handleMessages(MethodCall call) async {
     switch (call.method) {
@@ -54,6 +55,9 @@ class FlutterWebviewPlugin {
       case 'onHttpError':
         _onHttpError.add(WebViewHttpError(call.arguments['code'], call.arguments['url']));
         break;
+      case 'onOrderRequest':
+        _lightningLinkStream.add(call.arguments['order']);
+        break;
     }
   }
 
@@ -76,6 +80,8 @@ class FlutterWebviewPlugin {
 
   Stream<WebViewHttpError> get onHttpError => _onHttpError.stream;
 
+  Stream<String> get lightningLinkStream => _lightningLinkStream.stream;
+
   /// Start the Webview with [url]
   /// - [headers] specify additional HTTP headers
   /// - [withJavascript] enable Javascript or not for the Webview
@@ -188,6 +194,7 @@ class FlutterWebviewPlugin {
     _onScrollXChanged.close();
     _onScrollYChanged.close();
     _onHttpError.close();
+    _lightningLinkStream.close();
     _instance = null;
   }