[webview_flutter_android] Adds a WebViewFlutterApi (flutter#3324)

[webview_flutter_android] Adds a WebViewFlutterApi

packages/webview_flutter/webview_flutter_android/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 3.4.1
+
+* Fixes a potential bug where a `WebView` that was not added to the `InstanceManager` could be
+  returned by a `WebViewClient` or `WebChromeClient`.
+
 ## 3.4.0
 
 * Adds support to set text zoom of a page. See `AndroidWebViewController.setTextZoom`.

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

@@ -57,18 +57,16 @@ private static GeneratedAndroidWebView.FileChooserModeEnumData toFileChooserEnum
   /**
    * Stores the FileChooserParams instance and notifies Dart to create a new FileChooserParams
    * instance that is attached to this one.
-   *
-   * @return the instanceId of the stored instance
    */
-  public long create(WebChromeClient.FileChooserParams instance, Reply<Void> callback) {
-    final long instanceId = instanceManager.addHostCreatedInstance(instance);
-    create(
-        instanceId,
-        instance.isCaptureEnabled(),
-        Arrays.asList(instance.getAcceptTypes()),
-        toFileChooserEnumData(instance.getMode()),
-        instance.getFilenameHint(),
-        callback);
-    return instanceId;
+  public void create(WebChromeClient.FileChooserParams instance, Reply<Void> callback) {
+    if (!instanceManager.containsInstance(instance)) {
+      create(
+          instanceManager.addHostCreatedInstance(instance),
+          instance.isCaptureEnabled(),
+          Arrays.asList(instance.getAcceptTypes()),
+          toFileChooserEnumData(instance.getMode()),
+          instance.getFilenameHint(),
+          callback);
+    }
   }
 }

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

@@ -1574,6 +1574,42 @@ public void error(Throwable error) {
       }
     }
   }
+  /**
+   * Flutter API for `WebView`.
+   *
+   * <p>This class may handle instantiating and adding Dart instances that are attached to a native
+   * instance or receiving callback methods from an overridden native class.
+   *
+   * <p>See https://developer.android.com/reference/android/webkit/WebView.
+   *
+   * <p>Generated class from Pigeon that represents Flutter messages that can be called from Java.
+   */
+  public static class WebViewFlutterApi {
+    private final BinaryMessenger binaryMessenger;
+
+    public WebViewFlutterApi(BinaryMessenger argBinaryMessenger) {
+      this.binaryMessenger = argBinaryMessenger;
+    }
+
+    public interface Reply<T> {
+      void reply(T reply);
+    }
+    /** The codec used by WebViewFlutterApi. */
+    static MessageCodec<Object> getCodec() {
+      return new StandardMessageCodec();
+    }
+    /** Create a new Dart instance and add it to the `InstanceManager`. */
+    public void create(@NonNull Long identifierArg, Reply<Void> callback) {
+      BasicMessageChannel<Object> channel =
+          new BasicMessageChannel<>(
+              binaryMessenger, "dev.flutter.pigeon.WebViewFlutterApi.create", getCodec());
+      channel.send(
+          new ArrayList<Object>(Collections.singletonList(identifierArg)),
+          channelReply -> {
+            callback.reply(null);
+          });
+    }
+  }
   /** Generated interface from Pigeon that represents a handler of messages from Flutter. */
   public interface WebSettingsHostApi {
 

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

@@ -21,6 +21,7 @@
 public class WebChromeClientFlutterApiImpl extends WebChromeClientFlutterApi {
   private final BinaryMessenger binaryMessenger;
   private final InstanceManager instanceManager;
+  private final WebViewFlutterApiImpl webViewFlutterApi;
 
   /**
    * Creates a Flutter api that sends messages to Dart.
@@ -33,15 +34,16 @@ public WebChromeClientFlutterApiImpl(
     super(binaryMessenger);
     this.binaryMessenger = binaryMessenger;
     this.instanceManager = instanceManager;
+    webViewFlutterApi = new WebViewFlutterApiImpl(binaryMessenger, instanceManager);
   }
 
   /** Passes arguments from {@link WebChromeClient#onProgressChanged} to Dart. */
   public void onProgressChanged(
       WebChromeClient webChromeClient, WebView webView, Long progress, Reply<Void> callback) {
-    final Long webViewIdentifier = instanceManager.getIdentifierForStrongReference(webView);
-    if (webViewIdentifier == null) {
-      throw new IllegalStateException("Could not find identifier for WebView.");
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    final Long webViewIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView));
     super.onProgressChanged(
         getIdentifierForClient(webChromeClient), webViewIdentifier, progress, callback);
   }
@@ -53,17 +55,15 @@ public void onShowFileChooser(
       WebView webView,
       WebChromeClient.FileChooserParams fileChooserParams,
       Reply<List<String>> callback) {
-    Long paramsInstanceId = instanceManager.getIdentifierForStrongReference(fileChooserParams);
-    if (paramsInstanceId == null) {
-      final FileChooserParamsFlutterApiImpl flutterApi =
-          new FileChooserParamsFlutterApiImpl(binaryMessenger, instanceManager);
-      paramsInstanceId = flutterApi.create(fileChooserParams, reply -> {});
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    new FileChooserParamsFlutterApiImpl(binaryMessenger, instanceManager)
+        .create(fileChooserParams, reply -> {});
 
     onShowFileChooser(
         Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webChromeClient)),
         Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView)),
-        paramsInstanceId,
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(fileChooserParams)),
         callback);
   }
 

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

@@ -15,14 +15,17 @@
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugins.webviewflutter.GeneratedAndroidWebView.WebViewClientFlutterApi;
 import java.util.HashMap;
+import java.util.Objects;
 
 /**
  * Flutter Api implementation for {@link WebViewClient}.
  *
  * <p>Passes arguments of callbacks methods from a {@link WebViewClient} to Dart.
  */
 public class WebViewClientFlutterApiImpl extends WebViewClientFlutterApi {
+  private final BinaryMessenger binaryMessenger;
   private final InstanceManager instanceManager;
+  private final WebViewFlutterApiImpl webViewFlutterApi;
 
   @RequiresApi(api = Build.VERSION_CODES.M)
   static GeneratedAndroidWebView.WebResourceErrorData createWebResourceErrorData(
@@ -71,26 +74,28 @@ static GeneratedAndroidWebView.WebResourceRequestData createWebResourceRequestDa
   public WebViewClientFlutterApiImpl(
       BinaryMessenger binaryMessenger, InstanceManager instanceManager) {
     super(binaryMessenger);
+    this.binaryMessenger = binaryMessenger;
     this.instanceManager = instanceManager;
+    webViewFlutterApi = new WebViewFlutterApiImpl(binaryMessenger, instanceManager);
   }
 
   /** Passes arguments from {@link WebViewClient#onPageStarted} to Dart. */
   public void onPageStarted(
       WebViewClient webViewClient, WebView webView, String urlArg, Reply<Void> callback) {
-    final Long webViewIdentifier = instanceManager.getIdentifierForStrongReference(webView);
-    if (webViewIdentifier == null) {
-      throw new IllegalStateException("Could not find identifier for WebView.");
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    final Long webViewIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView));
     onPageStarted(getIdentifierForClient(webViewClient), webViewIdentifier, urlArg, callback);
   }
 
   /** Passes arguments from {@link WebViewClient#onPageFinished} to Dart. */
   public void onPageFinished(
       WebViewClient webViewClient, WebView webView, String urlArg, Reply<Void> callback) {
-    final Long webViewIdentifier = instanceManager.getIdentifierForStrongReference(webView);
-    if (webViewIdentifier == null) {
-      throw new IllegalStateException("Could not find identifier for WebView.");
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    final Long webViewIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView));
     onPageFinished(getIdentifierForClient(webViewClient), webViewIdentifier, urlArg, callback);
   }
 
@@ -105,10 +110,10 @@ public void onReceivedRequestError(
       WebResourceRequest request,
       WebResourceError error,
       Reply<Void> callback) {
-    final Long webViewIdentifier = instanceManager.getIdentifierForStrongReference(webView);
-    if (webViewIdentifier == null) {
-      throw new IllegalStateException("Could not find identifier for WebView.");
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    final Long webViewIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView));
     onReceivedRequestError(
         getIdentifierForClient(webViewClient),
         webViewIdentifier,
@@ -128,10 +133,10 @@ public void onReceivedRequestError(
       WebResourceRequest request,
       WebResourceErrorCompat error,
       Reply<Void> callback) {
-    final Long webViewIdentifier = instanceManager.getIdentifierForStrongReference(webView);
-    if (webViewIdentifier == null) {
-      throw new IllegalStateException("Could not find identifier for WebView.");
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    final Long webViewIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView));
     onReceivedRequestError(
         getIdentifierForClient(webViewClient),
         webViewIdentifier,
@@ -151,10 +156,10 @@ public void onReceivedError(
       String descriptionArg,
       String failingUrlArg,
       Reply<Void> callback) {
-    final Long webViewIdentifier = instanceManager.getIdentifierForStrongReference(webView);
-    if (webViewIdentifier == null) {
-      throw new IllegalStateException("Could not find identifier for WebView.");
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    final Long webViewIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView));
     onReceivedError(
         getIdentifierForClient(webViewClient),
         webViewIdentifier,
@@ -174,10 +179,10 @@ public void requestLoading(
       WebView webView,
       WebResourceRequest request,
       Reply<Void> callback) {
-    final Long webViewIdentifier = instanceManager.getIdentifierForStrongReference(webView);
-    if (webViewIdentifier == null) {
-      throw new IllegalStateException("Could not find identifier for WebView.");
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    final Long webViewIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView));
     requestLoading(
         getIdentifierForClient(webViewClient),
         webViewIdentifier,
@@ -190,10 +195,10 @@ public void requestLoading(
    */
   public void urlLoading(
       WebViewClient webViewClient, WebView webView, String urlArg, Reply<Void> callback) {
-    final Long webViewIdentifier = instanceManager.getIdentifierForStrongReference(webView);
-    if (webViewIdentifier == null) {
-      throw new IllegalStateException("Could not find identifier for WebView.");
-    }
+    webViewFlutterApi.create(webView, reply -> {});
+
+    final Long webViewIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(webView));
     urlLoading(getIdentifierForClient(webViewClient), webViewIdentifier, urlArg, callback);
   }
 

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

@@ -0,0 +1,59 @@
+// 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 android.webkit.WebView;
+import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
+import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugins.webviewflutter.GeneratedAndroidWebView.WebViewFlutterApi;
+
+/**
+ * Flutter API implementation for `WebView`.
+ *
+ * <p>This class may handle adding native instances that are attached to a Dart instance or passing
+ * arguments of callbacks methods to a Dart instance.
+ */
+public class WebViewFlutterApiImpl {
+  // To ease adding additional methods, this value is added prematurely.
+  @SuppressWarnings({"unused", "FieldCanBeLocal"})
+  private final BinaryMessenger binaryMessenger;
+
+  private final InstanceManager instanceManager;
+  private WebViewFlutterApi api;
+
+  /**
+   * Constructs a {@link WebViewFlutterApiImpl}.
+   *
+   * @param binaryMessenger used to communicate with Dart over asynchronous messages
+   * @param instanceManager maintains instances stored to communicate with attached Dart objects
+   */
+  public WebViewFlutterApiImpl(
+      @NonNull BinaryMessenger binaryMessenger, @NonNull InstanceManager instanceManager) {
+    this.binaryMessenger = binaryMessenger;
+    this.instanceManager = instanceManager;
+    api = new WebViewFlutterApi(binaryMessenger);
+  }
+
+  /**
+   * Stores the `WebView` instance and notifies Dart to create and store a new `WebView` instance
+   * that is attached to this one. If `instance` has already been added, this method does nothing.
+   */
+  public void create(@NonNull WebView instance, @NonNull WebViewFlutterApi.Reply<Void> callback) {
+    if (!instanceManager.containsInstance(instance)) {
+      api.create(instanceManager.addHostCreatedInstance(instance), callback);
+    }
+  }
+
+  /**
+   * Sets the Flutter API used to send messages to Dart.
+   *
+   * <p>This is only visible for testing.
+   */
+  @VisibleForTesting
+  void setApi(@NonNull WebViewFlutterApi api) {
+    this.api = api;
+  }
+}

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

@@ -47,8 +47,6 @@ public class WebChromeClientTest {
   public void setUp() {
     instanceManager = InstanceManager.open(identifier -> {});
 
-    instanceManager.addDartCreatedInstance(mockWebView, 0L);
-
     final WebChromeClientCreator webChromeClientCreator =
         new WebChromeClientCreator() {
           @Override

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

@@ -43,8 +43,6 @@ public class WebViewClientTest {
   public void setUp() {
     instanceManager = InstanceManager.open(identifier -> {});
 
-    instanceManager.addDartCreatedInstance(mockWebView, 0L);
-
     final WebViewClientCreator webViewClientCreator =
         new WebViewClientCreator() {
           @Override

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

@@ -7,6 +7,7 @@
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.eq;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
@@ -18,6 +19,7 @@
 import android.webkit.WebChromeClient;
 import android.webkit.WebViewClient;
 import io.flutter.plugin.common.BinaryMessenger;
+import io.flutter.plugins.webviewflutter.GeneratedAndroidWebView.WebViewFlutterApi;
 import io.flutter.plugins.webviewflutter.WebViewHostApiImpl.WebViewPlatformView;
 import java.util.HashMap;
 import java.util.Objects;
@@ -314,4 +316,23 @@ public void destroy() {
 
     assertTrue(destroyCalled[0]);
   }
+
+  @Test
+  public void flutterApiCreate() {
+    final InstanceManager instanceManager = InstanceManager.open(identifier -> {});
+
+    final WebViewFlutterApiImpl flutterApiImpl =
+        new WebViewFlutterApiImpl(mockBinaryMessenger, instanceManager);
+
+    final WebViewFlutterApi mockFlutterApi = mock(WebViewFlutterApi.class);
+    flutterApiImpl.setApi(mockFlutterApi);
+
+    flutterApiImpl.create(mockWebView, reply -> {});
+
+    final long instanceIdentifier =
+        Objects.requireNonNull(instanceManager.getIdentifierForStrongReference(mockWebView));
+    verify(mockFlutterApi).create(eq(instanceIdentifier), any());
+
+    instanceManager.close();
+  }
 }