[webview_flutter_android] Adds dispose methods for HostApi and FlutterApi of JavaObject (flutter#6172)

Author: bparrishMines

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.9.5
+
+* Adds dispose methods for HostApi and FlutterApi of JavaObject.
+
 ## 2.9.4
 
 * Fixes avoid_redundant_argument_values lint warnings and minor typos.

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

@@ -1,7 +1,7 @@
 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-// Autogenerated from Pigeon (v3.0.3), do not edit directly.
+// Autogenerated from Pigeon (v3.2.0), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 
 package io.flutter.plugins.webviewflutter;
@@ -271,6 +271,87 @@ public interface Result<T> {
     void error(Throwable error);
   }
 
+  private static class JavaObjectHostApiCodec extends StandardMessageCodec {
+    public static final JavaObjectHostApiCodec INSTANCE = new JavaObjectHostApiCodec();
+
+    private JavaObjectHostApiCodec() {}
+  }
+
+  /** Generated interface from Pigeon that represents a handler of messages from Flutter. */
+  public interface JavaObjectHostApi {
+    void dispose(@NonNull Long identifier);
+
+    /** The codec used by JavaObjectHostApi. */
+    static MessageCodec<Object> getCodec() {
+      return JavaObjectHostApiCodec.INSTANCE;
+    }
+
+    /**
+     * Sets up an instance of `JavaObjectHostApi` to handle messages through the `binaryMessenger`.
+     */
+    static void setup(BinaryMessenger binaryMessenger, JavaObjectHostApi api) {
+      {
+        BasicMessageChannel<Object> channel =
+            new BasicMessageChannel<>(
+                binaryMessenger, "dev.flutter.pigeon.JavaObjectHostApi.dispose", getCodec());
+        if (api != null) {
+          channel.setMessageHandler(
+              (message, reply) -> {
+                Map<String, Object> wrapped = new HashMap<>();
+                try {
+                  ArrayList<Object> args = (ArrayList<Object>) message;
+                  Number identifierArg = (Number) args.get(0);
+                  if (identifierArg == null) {
+                    throw new NullPointerException("identifierArg unexpectedly null.");
+                  }
+                  api.dispose((identifierArg == null) ? null : identifierArg.longValue());
+                  wrapped.put("result", null);
+                } catch (Error | RuntimeException exception) {
+                  wrapped.put("error", wrapError(exception));
+                }
+                reply.reply(wrapped);
+              });
+        } else {
+          channel.setMessageHandler(null);
+        }
+      }
+    }
+  }
+
+  private static class JavaObjectFlutterApiCodec extends StandardMessageCodec {
+    public static final JavaObjectFlutterApiCodec INSTANCE = new JavaObjectFlutterApiCodec();
+
+    private JavaObjectFlutterApiCodec() {}
+  }
+
+  /** Generated class from Pigeon that represents Flutter messages that can be called from Java. */
+  public static class JavaObjectFlutterApi {
+    private final BinaryMessenger binaryMessenger;
+
+    public JavaObjectFlutterApi(BinaryMessenger argBinaryMessenger) {
+      this.binaryMessenger = argBinaryMessenger;
+    }
+
+    public interface Reply<T> {
+      void reply(T reply);
+    }
+
+    static MessageCodec<Object> getCodec() {
+      return JavaObjectFlutterApiCodec.INSTANCE;
+    }
+
+    public void dispose(@NonNull Long identifierArg, Reply<Void> callback) {
+      BasicMessageChannel<Object> channel =
+          new BasicMessageChannel<>(
+              binaryMessenger, "dev.flutter.pigeon.JavaObjectFlutterApi.dispose", getCodec());
+      channel.send(
+          new ArrayList<Object>(Arrays.asList(identifierArg)),
+          channelReply -> {
+            callback.reply(null);
+          });
+    }
+  }
+
   private static class CookieManagerHostApiCodec extends StandardMessageCodec {
     public static final CookieManagerHostApiCodec INSTANCE = new CookieManagerHostApiCodec();
 

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

@@ -0,0 +1,32 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.plugins.webviewflutter;
+
+import androidx.annotation.NonNull;
+
+/**
+ * A pigeon Host API implementation that handles creating {@link Object}s and invoking its static
+ * and instance methods.
+ *
+ * <p>{@link Object} instances created by {@link JavaObjectHostApiImpl} are used to intercommunicate
+ * with a paired Dart object.
+ */
+public class JavaObjectHostApiImpl implements GeneratedAndroidWebView.JavaObjectHostApi {
+  private final InstanceManager instanceManager;
+
+  /**
+   * Constructs a {@link JavaObjectHostApiImpl}.
+   *
+   * @param instanceManager maintains instances stored to communicate with Dart objects
+   */
+  public JavaObjectHostApiImpl(InstanceManager instanceManager) {
+    this.instanceManager = instanceManager;
+  }
+
+  @Override
+  public void dispose(@NonNull Long identifier) {
+    instanceManager.remove(identifier);
+  }
+}

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

@@ -0,0 +1,32 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package io.flutter.plugins.webviewflutter;
+
+import static org.junit.Assert.assertNull;
+
+import org.junit.Test;
+
+public class JavaObjectHostApiTest {
+  @Test
+  public void dispose() {
+    final InstanceManager instanceManager = InstanceManager.open(identifier -> {});
+
+    final JavaObjectHostApiImpl hostApi = new JavaObjectHostApiImpl(instanceManager);
+
+    Object object = new Object();
+    instanceManager.addDartCreatedInstance(object, 0);
+
+    // To free object for garbage collection.
+    //noinspection UnusedAssignment
+    object = null;
+
+    hostApi.dispose(0L);
+    Runtime.getRuntime().gc();
+
+    assertNull(instanceManager.getInstance(0));
+
+    instanceManager.close();
+  }
+}

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

@@ -13,6 +13,7 @@ import 'dart:typed_data';
 import 'dart:ui';
 
 import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart' show BinaryMessenger;
 import 'package:flutter/widgets.dart' show AndroidViewSurface;
 
 import 'android_webview.pigeon.dart';
@@ -22,17 +23,36 @@ import 'instance_manager.dart';
 /// Root of the Java class hierarchy.
 ///
 /// See https://docs.oracle.com/javase/8/docs/api/java/lang/Object.html.
-abstract class JavaObject with Copyable {
+class JavaObject with Copyable {
   /// Constructs a [JavaObject] without creating the associated Java object.
   ///
   /// This should only be used by subclasses created by this library or to
   /// create copies.
-  JavaObject.detached();
+  JavaObject.detached({
+    BinaryMessenger? binaryMessenger,
+    InstanceManager? instanceManager,
+  }) : _api = JavaObjectHostApiImpl(
+          binaryMessenger: binaryMessenger,
+          instanceManager: instanceManager,
+        );
 
   /// Global instance of [InstanceManager].
   static final InstanceManager globalInstanceManager = InstanceManager(
     onWeakReferenceRemoved: (_) {},
   );
+
+  /// Pigeon Host Api implementation for [JavaObject].
+  final JavaObjectHostApiImpl _api;
+
+  /// Release the reference to a native Java instance.
+  static void dispose(JavaObject instance) {
+    instance._api.instanceManager.removeWeakReference(instance);
+  }
+
+  @override
+  JavaObject copy() {
+    return JavaObject.detached();
+  }
 }
 
 /// An Android View that displays web pages.

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

@@ -1,7 +1,7 @@
 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-// Autogenerated from Pigeon (v3.0.3), do not edit directly.
+// Autogenerated from Pigeon (v3.2.0), do not edit directly.
 // See also: https://pub.dev/packages/pigeon
 // ignore_for_file: public_member_api_docs, non_constant_identifier_names, avoid_as, unused_import, unnecessary_parenthesis, prefer_null_aware_operators, omit_local_variable_types, unused_shown_name
 // @dart = 2.12
@@ -78,6 +78,78 @@ class WebResourceErrorData {
   }
 }
 
+class _JavaObjectHostApiCodec extends StandardMessageCodec {
+  const _JavaObjectHostApiCodec();
+}
+
+class JavaObjectHostApi {
+  /// Constructor for [JavaObjectHostApi].  The [binaryMessenger] named argument is
+  /// available for dependency injection.  If it is left null, the default
+  /// BinaryMessenger will be used which routes to the host platform.
+  JavaObjectHostApi({BinaryMessenger? binaryMessenger})
+      : _binaryMessenger = binaryMessenger;
+
+  final BinaryMessenger? _binaryMessenger;
+
+  static const MessageCodec<Object?> codec = _JavaObjectHostApiCodec();
+
+  Future<void> dispose(int arg_identifier) async {
+    final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+        'dev.flutter.pigeon.JavaObjectHostApi.dispose', codec,
+        binaryMessenger: _binaryMessenger);
+    final Map<Object?, Object?>? replyMap =
+        await channel.send(<Object?>[arg_identifier]) as Map<Object?, Object?>?;
+    if (replyMap == null) {
+      throw PlatformException(
+        code: 'channel-error',
+        message: 'Unable to establish connection on channel.',
+      );
+    } else if (replyMap['error'] != null) {
+      final Map<Object?, Object?> error =
+          (replyMap['error'] as Map<Object?, Object?>?)!;
+      throw PlatformException(
+        code: (error['code'] as String?)!,
+        message: error['message'] as String?,
+        details: error['details'],
+      );
+    } else {
+      return;
+    }
+  }
+}
+
+class _JavaObjectFlutterApiCodec extends StandardMessageCodec {
+  const _JavaObjectFlutterApiCodec();
+}
+
+abstract class JavaObjectFlutterApi {
+  static const MessageCodec<Object?> codec = _JavaObjectFlutterApiCodec();
+
+  void dispose(int identifier);
+  static void setup(JavaObjectFlutterApi? api,
+      {BinaryMessenger? binaryMessenger}) {
+    {
+      final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+          'dev.flutter.pigeon.JavaObjectFlutterApi.dispose', codec,
+          binaryMessenger: binaryMessenger);
+      if (api == null) {
+        channel.setMessageHandler(null);
+      } else {
+        channel.setMessageHandler((Object? message) async {
+          assert(message != null,
+              'Argument for dev.flutter.pigeon.JavaObjectFlutterApi.dispose was null.');
+          final List<Object?> args = (message as List<Object?>?)!;
+          final int? arg_identifier = (args[0] as int?);
+          assert(arg_identifier != null,
+              'Argument for dev.flutter.pigeon.JavaObjectFlutterApi.dispose was null, expected non-null int.');
+          api.dispose(arg_identifier!);
+          return;
+        });
+      }
+    }
+  }
+}
+
 class _CookieManagerHostApiCodec extends StandardMessageCodec {
   const _CookieManagerHostApiCodec();
 }

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

@@ -36,11 +36,14 @@ WebResourceError _toWebResourceError(WebResourceErrorData data) {
 class AndroidWebViewFlutterApis {
   /// Creates a [AndroidWebViewFlutterApis].
   AndroidWebViewFlutterApis({
+    JavaObjectFlutterApiImpl? javaObjectFlutterApi,
     DownloadListenerFlutterApiImpl? downloadListenerFlutterApi,
     WebViewClientFlutterApiImpl? webViewClientFlutterApi,
     WebChromeClientFlutterApiImpl? webChromeClientFlutterApi,
     JavaScriptChannelFlutterApiImpl? javaScriptChannelFlutterApi,
   }) {
+    this.javaObjectFlutterApi =
+        javaObjectFlutterApi ?? JavaObjectFlutterApiImpl();
     this.downloadListenerFlutterApi =
         downloadListenerFlutterApi ?? DownloadListenerFlutterApiImpl();
     this.webViewClientFlutterApi =
@@ -58,6 +61,9 @@ class AndroidWebViewFlutterApis {
   /// This should only be changed for testing purposes.
   static AndroidWebViewFlutterApis instance = AndroidWebViewFlutterApis();
 
+  /// Handles callbacks methods for the native Java Object class.
+  late final JavaObjectFlutterApi javaObjectFlutterApi;
+
   /// Flutter Api for [DownloadListener].
   late final DownloadListenerFlutterApiImpl downloadListenerFlutterApi;
 
@@ -73,6 +79,7 @@ class AndroidWebViewFlutterApis {
   /// Ensures all the Flutter APIs have been setup to receive calls from native code.
   void ensureSetUp() {
     if (!_haveBeenSetUp) {
+      JavaObjectFlutterApi.setup(javaObjectFlutterApi);
       DownloadListenerFlutterApi.setup(downloadListenerFlutterApi);
       WebViewClientFlutterApi.setup(webViewClientFlutterApi);
       WebChromeClientFlutterApi.setup(webChromeClientFlutterApi);
@@ -82,6 +89,40 @@ class AndroidWebViewFlutterApis {
   }
 }
 
+/// Handles methods calls to the native Java Object class.
+class JavaObjectHostApiImpl extends JavaObjectHostApi {
+  /// Constructs a [JavaObjectHostApiImpl].
+  JavaObjectHostApiImpl({
+    this.binaryMessenger,
+    InstanceManager? instanceManager,
+  })  : instanceManager = instanceManager ?? JavaObject.globalInstanceManager,
+        super(binaryMessenger: binaryMessenger);
+
+  /// Receives binary data across the Flutter platform barrier.
+  ///
+  /// If it is null, the default BinaryMessenger will be used which routes to
+  /// the host platform.
+  final BinaryMessenger? binaryMessenger;
+
+  /// Maintains instances stored to communicate with native language objects.
+  final InstanceManager instanceManager;
+}
+
+/// Handles callbacks methods for the native Java Object class.
+class JavaObjectFlutterApiImpl implements JavaObjectFlutterApi {
+  /// Constructs a [JavaObjectFlutterApiImpl].
+  JavaObjectFlutterApiImpl({InstanceManager? instanceManager})
+      : instanceManager = instanceManager ?? JavaObject.globalInstanceManager;
+
+  /// Maintains instances stored to communicate with native language objects.
+  final InstanceManager instanceManager;
+
+  @override
+  void dispose(int identifier) {
+    instanceManager.remove(identifier);
+  }
+}
+
 /// Host api implementation for [WebView].
 class WebViewHostApiImpl extends WebViewHostApi {
   /// Constructs a [WebViewHostApiImpl].