Implementation of loadFlutterAsset on Android

Author: mvanbeusekom

packages/webview_flutter/webview_flutter_android/android/build.gradle

@@ -58,8 +58,4 @@ android {
             }
         }
     }
-    compileOptions {
-        sourceCompatibility JavaVersion.VERSION_1_8
-        targetCompatibility JavaVersion.VERSION_1_8
-    }
 }

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

@@ -0,0 +1,99 @@
+// 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.content.res.AssetManager;
+import androidx.annotation.NonNull;
+import io.flutter.embedding.engine.plugins.FlutterPlugin;
+import io.flutter.plugin.common.PluginRegistry;
+import java.io.IOException;
+
+/**
+ * Provides access to the assets registered as part of the App bundle.
+ */
+abstract class FlutterAssetManager {
+  final AssetManager assetManager;
+
+  /**
+   * Constructs a new instance of the {@link FlutterAssetManager}.
+   *
+   * @param assetManager Instance of Android's {@link AssetManager} used to access assets within the App bundle.
+   */
+  public FlutterAssetManager(AssetManager assetManager) {
+    this.assetManager = assetManager;
+  }
+
+  /**
+   * Gets the relative file path to the Flutter asset with the given name, including the file's extension, e.g., "myImage.jpg".
+   *
+   * The returned file path is relative to the Android app's standard asset's directory. Therefore,
+   * the returned path is appropriate to pass to Android's AssetManager, but the path is not
+   * appropriate to load as an absolute path.
+   */
+  abstract String getAssetFilePathByName(String name);
+
+  /**
+   * Returns a String array of all the assets at the given path.
+   *
+   * @param path A relative path within the assets, i.e., "docs/home.html". This value cannot be null.
+   * @return String[] Array of strings, one for each asset. These file names are relative to 'path'. This value may be null.
+   * @throws IOException Throws an IOException in case I/O operations were interrupted.
+   */
+  public String[] list(@NonNull String path) throws IOException {
+    return assetManager.list(path);
+  }
+
+  /**
+   * Provides access to assets using the {@link PluginRegistry.Registrar} for looking up file paths to Flutter assets.
+   *
+   * @deprecated The {@link RegistrarFlutterAssetManager} is for Flutter's v1 embedding. For
+   *     instructions on migrating a plugin from Flutter's v1 Android embedding to v2, visit
+   *     http://flutter.dev/go/android-plugin-migration
+   */
+  @Deprecated
+  static class RegistrarFlutterAssetManager extends FlutterAssetManager {
+    final PluginRegistry.Registrar registrar;
+
+    /**
+     * Constructs a new instance of the {@link RegistrarFlutterAssetManager}.
+     *
+     * @param assetManager Instance of Android's {@link AssetManager} used to access assets within the App bundle.
+     * @param registrar Instance of {@link io.flutter.plugin.common.PluginRegistry.Registrar} used to look up file paths to assets registered by Flutter.
+     */
+    RegistrarFlutterAssetManager(AssetManager assetManager, PluginRegistry.Registrar registrar) {
+      super(assetManager);
+      this.registrar = registrar;
+    }
+
+    @Override
+    public String getAssetFilePathByName(String name) {
+      return registrar.lookupKeyForAsset(name);
+    }
+  }
+
+  /**
+   * Provides access to assets using the {@link FlutterPlugin.FlutterAssets} for looking up file paths to Flutter assets.
+   */
+  static class PluginBindingFlutterAssetManager extends FlutterAssetManager {
+    final FlutterPlugin.FlutterAssets flutterAssets;
+
+    /**
+     * Constructs a new instance of the {@link PluginBindingFlutterAssetManager}.
+     *
+     * @param assetManager Instance of Android's {@link AssetManager} used to access assets within the App bundle.
+     * @param flutterAssets Instance of {@link io.flutter.embedding.engine.plugins.FlutterPlugin.FlutterAssets} used to look up file paths to assets registered by Flutter.
+     */
+    PluginBindingFlutterAssetManager(AssetManager assetManager, FlutterPlugin.FlutterAssets flutterAssets) {
+      super(assetManager);
+      this.flutterAssets = flutterAssets;
+    }
+
+    @Override
+    public String getAssetFilePathByName(String name) {
+      return flutterAssets.getAssetFilePathByName(name);
+    }
+  }
+}
+

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

@@ -0,0 +1,43 @@
+// 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.content.Context;
+import android.webkit.WebView;
+import io.flutter.plugins.webviewflutter.GeneratedAndroidWebView.FlutterAssetManagerHostApi;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+
+/**
+ * Host api implementation for {@link WebView}.
+ *
+ * <p>Handles creating {@link WebView}s that intercommunicate with a paired Dart object.
+ */
+public class FlutterAssetManagerHostApiImpl implements FlutterAssetManagerHostApi {
+  final FlutterAssetManager flutterAssetManager;
+
+  /**
+   * Constructs a new instance of {@link FlutterAssetManagerHostApiImpl}.
+   */
+  public FlutterAssetManagerHostApiImpl(FlutterAssetManager flutterAssetManager) {
+    this.flutterAssetManager = flutterAssetManager;
+  }
+
+  @Override
+  public List<String> list(String path) {
+    try {
+      String[] paths = flutterAssetManager.list(path);
+      return Arrays.asList(paths);
+    } catch (IOException ex) {
+      throw new RuntimeException(ex.getMessage());
+    }
+  }
+
+  @Override
+  public String getAssetFilePathByName(String name) {
+    return flutterAssetManager.getAssetFilePathByName(name);
+  }
+}