[webview_flutter_android][webview_flutter_wkwebview] Adds support for getUserAgent for webview_flutter platform implementations (#4927)

Platform implementations for #4472

Author: bparrishMines

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 3.12.0
+
+* Adds support for `PlatformWebViewController.getUserAgent`.
+
 ## 3.11.0
 
 * Adds support to register a callback to receive JavaScript console messages. See `AndroidWebViewController.onConsoleMessage`.
@@ -27,7 +31,7 @@
 ## 3.9.2
 
 * Fixes bug where `PlatformWebViewWidget` doesn't rebuild when the controller or PlatformView
-  implementation flag changes. 
+  implementation flag changes.
 
 ## 3.9.1
 

packages/webview_flutter/webview_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/GeneratedAndroidWebView.java

@@ -1790,6 +1790,9 @@ public interface WebSettingsHostApi {
 
     void setTextZoom(@NonNull Long instanceId, @NonNull Long textZoom);
 
+    @NonNull
+    String getUserAgentString(@NonNull Long instanceId);
+
     /** The codec used by WebSettingsHostApi. */
     static @NonNull MessageCodec<Object> getCodec() {
       return new StandardMessageCodec();
@@ -2179,6 +2182,33 @@ static void setup(@NonNull BinaryMessenger binaryMessenger, @Nullable WebSetting
           channel.setMessageHandler(null);
         }
       }
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<>(
+                binaryMessenger,
+                "dev.flutter.pigeon.webview_flutter_android.WebSettingsHostApi.getUserAgentString",
+                getCodec());
+        if (api != null) {
+          channel.setMessageHandler(
+              (message, reply) -> {
+                ArrayList<Object> wrapped = new ArrayList<Object>();
+                ArrayList<Object> args = (ArrayList<Object>) message;
+                Number instanceIdArg = (Number) args.get(0);
+                try {
+                  String output =
+                      api.getUserAgentString(
+                          (instanceIdArg == null) ? null : instanceIdArg.longValue());
+                  wrapped.add(0, output);
+                } catch (Throwable exception) {
+                  ArrayList<Object> wrappedError = wrapError(exception);
+                  wrapped = wrappedError;
+                }
+                reply.reply(wrapped);
+              });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
     }
   }
   /** Generated interface from Pigeon that represents a handler of messages from Flutter. */

packages/webview_flutter/webview_flutter_android/android/src/main/java/io/flutter/plugins/webviewflutter/WebSettingsHostApiImpl.java

@@ -132,4 +132,11 @@ public void setTextZoom(@NonNull Long instanceId, @NonNull Long textZoom) {
     final WebSettings webSettings = Objects.requireNonNull(instanceManager.getInstance(instanceId));
     webSettings.setTextZoom(textZoom.intValue());
   }
+
+  @NonNull
+  @Override
+  public String getUserAgentString(@NonNull Long instanceId) {
+    final WebSettings webSettings = Objects.requireNonNull(instanceManager.getInstance(instanceId));
+    return webSettings.getUserAgentString();
+  }
 }

packages/webview_flutter/webview_flutter_android/android/src/test/java/io/flutter/plugins/webviewflutter/WebSettingsTest.java

@@ -4,6 +4,7 @@
 
 package io.flutter.plugins.webviewflutter;
 
+import static org.junit.Assert.assertEquals;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
@@ -117,4 +118,11 @@ public void setTextZoom() {
     testHostApiImpl.setTextZoom(0L, 100L);
     verify(mockWebSettings).setTextZoom(100);
   }
+
+  @Test
+  public void getUserAgentString() {
+    final String userAgent = "str";
+    when(mockWebSettings.getUserAgentString()).thenReturn(userAgent);
+    assertEquals(testHostApiImpl.getUserAgentString(0L), userAgent);
+  }
 }

packages/webview_flutter/webview_flutter_android/example/integration_test/webview_flutter_test.dart

@@ -342,7 +342,7 @@ Future<void> main() async {
 
     await pageFinished.future;
 
-    final String customUserAgent = await _getUserAgent(controller);
+    final String? customUserAgent = await controller.getUserAgent();
     expect(customUserAgent, 'Custom_User_Agent1');
   });
 
@@ -1353,19 +1353,6 @@ Future<void> main() async {
   });
 }
 
-/// Returns the value used for the HTTP User-Agent: request header in subsequent HTTP requests.
-Future<String> _getUserAgent(PlatformWebViewController controller) async {
-  return _runJavaScriptReturningResult(controller, 'navigator.userAgent;');
-}
-
-Future<String> _runJavaScriptReturningResult(
-  PlatformWebViewController controller,
-  String js,
-) async {
-  return jsonDecode(await controller.runJavaScriptReturningResult(js) as String)
-      as String;
-}
-
 class ResizableWebView extends StatefulWidget {
   const ResizableWebView({
     super.key,

packages/webview_flutter/webview_flutter_android/lib/src/android_webview.dart

@@ -695,6 +695,11 @@ class WebSettings extends JavaObject {
     return api.setSetTextZoomFromInstance(this, textZoom);
   }
 
+  /// Gets the WebView's user-agent string.
+  Future<String> getUserAgentString() {
+    return api.getUserAgentStringFromInstance(this);
+  }
+
   @override
   WebSettings copy() {
     return WebSettings.detached(

packages/webview_flutter/webview_flutter_android/lib/src/android_webview.g.dart

@@ -1499,6 +1499,34 @@ class WebSettingsHostApi {
       return;
     }
   }
+
+  Future<String> getUserAgentString(int arg_instanceId) async {
+    final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+        'dev.flutter.pigeon.webview_flutter_android.WebSettingsHostApi.getUserAgentString',
+        codec,
+        binaryMessenger: _binaryMessenger);
+    final List<Object?>? replyList =
+        await channel.send(<Object?>[arg_instanceId]) as List<Object?>?;
+    if (replyList == null) {
+      throw PlatformException(
+        code: 'channel-error',
+        message: 'Unable to establish connection on channel.',
+      );
+    } else if (replyList.length > 1) {
+      throw PlatformException(
+        code: replyList[0]! as String,
+        message: replyList[1] as String?,
+        details: replyList[2],
+      );
+    } else if (replyList[0] == null) {
+      throw PlatformException(
+        code: 'null-error',
+        message: 'Host platform returned null value for non-null return value.',
+      );
+    } else {
+      return (replyList[0] as String?)!;
+    }
+  }
 }
 
 class JavaScriptChannelHostApi {

packages/webview_flutter/webview_flutter_android/lib/src/android_webview_api_impls.dart

@@ -553,6 +553,11 @@ class WebSettingsHostApiImpl extends WebSettingsHostApi {
       enabled,
     );
   }
+
+  /// Helper method to convert instances ids to objects.
+  Future<String> getUserAgentStringFromInstance(WebSettings instance) {
+    return getUserAgentString(instanceManager.getIdentifier(instance)!);
+  }
 }
 
 /// Host api implementation for [JavaScriptChannel].

packages/webview_flutter/webview_flutter_android/lib/src/android_webview_controller.dart

@@ -617,6 +617,9 @@ class AndroidWebViewController extends PlatformWebViewController {
     return _webChromeClient.setSynchronousReturnValueForOnConsoleMessage(
         _onConsoleLogCallback != null);
   }
+
+  @override
+  Future<String?> getUserAgent() => _webView.settings.getUserAgentString();
 }
 
 /// Android implementation of [PlatformWebViewPermissionRequest].

packages/webview_flutter/webview_flutter_android/pigeons/android_webview.dart

@@ -299,6 +299,8 @@ abstract class WebSettingsHostApi {
   void setAllowFileAccess(int instanceId, bool enabled);
 
   void setTextZoom(int instanceId, int textZoom);
+
+  String getUserAgentString(int instanceId);
 }
 
 @HostApi(dartHostTestHandler: 'TestJavaScriptChannelHostApi')