[jnigen] migrate in_app_java example to Dart API (#2671)

Author: goderbauer

pkgs/jnigen/example/in_app_java/README.md

@@ -1,28 +1,31 @@
 # In-App Java Example
 
 This example shows how to write custom java code in `android/app/src` and call
-it using `jnigen` generated bindings.
+it using bindings generated by `jnigen`.
 
-#### How to run this example:
+### How to run this example:
 
 - Run `flutter run` to run the app.
 
 - To regenerate bindings after changing Java code, run
-  `flutter pub run jnigen --config jnigen.yaml`. This requires at least one APK
-  build to have been run before, so that it's possible for `jnigen` to obtain
-  classpaths of Android Gradle libraries. Therefore, once run
-  `flutter build apk` before generating bindings for the first time, or after a
-  `flutter clean`.
+  `dart run tool/jnigen.dart`. This requires at least one APK build to have
+  been run before, so that  `jnigen` can obtain classpaths of Android Gradle
+  libraries. Therefore, run `flutter build apk` once before generating bindings
+  for the first time, or after a `flutter clean`.
 
-#### General steps
+### General steps
 
-These are general steps to integrate Java code into a flutter project using
+These are general steps to integrate Java code into a Flutter project using
 `jnigen`.
 
-- Write Java code in suitable package folder, under `android/` subproject of the
-  flutter app.
-- Create A jnigen config like `jnigen.yaml` in this example.
-- Generate bindings using jnigen config.
-- Add proguard rules to exclude your custom classes from tree shaking, since
-  they are always accessed reflectively in JNI.
+- Place Java code in a suitable package folder under the `android/` subproject
+  of the flutter app.
+- Create a `jnigen` configuration script like `tool/jnigen.dart` in this
+  example.
+- Generate bindings by running that script with `dart run`.
+- To prevent tree shaking of your custom classes (which are always accessed
+  reflectively in JNI) use either the `@Keep` annotation 
+  (`androidx.annotation.Keep`) for code written in the application itself, or
+  a [proguard-rules file](https://github.com/dart-lang/native/blob/main/pkgs/jnigen/example/in_app_java/android/app/proguard-rules.pro)
+  for external libraries.
 - Build and run the app.

pkgs/jnigen/example/in_app_java/jnigen.yaml

@@ -7,7 +7,7 @@ import 'package:jni/jni.dart';
 
 // The hierarchy created in generated code will mirror the java package
 // structure.
-import 'android_utils.dart';
+import 'android_utils.g.dart';
 
 JObject activity = JObject.fromReference(Jni.getCurrentActivity());
 JObject context = JObject.fromReference(Jni.getCachedApplicationContext());

pkgs/jnigen/example/in_app_java/lib/android_utils.dart renamed to pkgs/jnigen/example/in_app_java/lib/android_utils.g.dart

@@ -15,9 +15,6 @@ dependencies:
     sdk: flutter
   jni:
     path: ../../../jni/
-
-  # The following adds the Cupertino Icons font to your application.
-  # Use with the CupertinoIcons class for iOS style icons.
   cupertino_icons: ^1.0.2
 
 dev_dependencies:
@@ -29,39 +26,5 @@ dev_dependencies:
   flutter_lints: ^6.0.0
 
 flutter:
-
-  # The following line ensures that the Material Icons font is
-  # included with your application, so that you can use the icons in
-  # the material Icons class.
   uses-material-design: true
 
-  # To add assets to your application, add an assets section, like this:
-  # assets:
-  #   - images/a_dot_burr.jpeg
-  #   - images/a_dot_ham.jpeg
-
-  # An image asset can refer to one or more resolution-specific "variants", see
-  # https://flutter.dev/assets-and-images/#resolution-aware
-
-  # For details regarding adding assets from package dependencies, see
-  # https://flutter.dev/assets-and-images/#from-packages
-
-  # To add custom fonts to your application, add a fonts section here,
-  # in this "flutter" section. Each entry in this list should have a
-  # "family" key with the font family name, and a "fonts" key with a
-  # list giving the asset and other descriptors for the font. For
-  # example:
-  # fonts:
-  #   - family: Schyler
-  #     fonts:
-  #       - asset: fonts/Schyler-Regular.ttf
-  #       - asset: fonts/Schyler-Italic.ttf
-  #         style: italic
-  #   - family: Trajan Pro
-  #     fonts:
-  #       - asset: fonts/TrajanPro.ttf
-  #       - asset: fonts/TrajanPro_Bold.ttf
-  #         weight: 700
-  #
-  # For details regarding fonts from package dependencies,
-  # see https://flutter.dev/custom-fonts/#from-packages

pkgs/jnigen/example/in_app_java/lib/main.dart

@@ -0,0 +1,26 @@
+import 'dart:io';
+
+import 'package:jnigen/jnigen.dart';
+
+void main(List<String> args) {
+  final packageRoot = Platform.script.resolve('../');
+  generateJniBindings(
+    Config(
+      outputConfig: OutputConfig(
+        dartConfig: DartCodeOutputConfig(
+          path: packageRoot.resolve('lib/android_utils.g.dart'),
+          structure: OutputStructure.singleFile,
+        ),
+      ),
+      androidSdkConfig: AndroidSdkConfig(addGradleDeps: true),
+      sourcePath: [packageRoot.resolve('android/app/src/main/java')],
+      classes: [
+        'com.example.in_app_java', // Generate the entire package
+        'androidx.emoji2.text.EmojiCompat', // From gradle's compile classpath
+        'androidx.emoji2.text.DefaultEmojiCompatConfig', // From gradle's compile classpath
+        'android.os.Build', // from gradle's compile classpath
+        'java.util.HashMap', // from gradle's compile classpath
+      ],
+    ),
+  );
+}

pkgs/jnigen/example/in_app_java/pubspec.yaml

@@ -14,10 +14,10 @@ import 'test_util/test_util.dart';
 /// Generates bindings using jnigen config in [exampleName] and compares
 /// them to provided reference outputs.
 ///
-/// [dartOutput] and [cOutput] are relative paths from example project dir.
+/// [dartOutput] is a relative path from the example project dir.
 ///
 /// Pass [isLargeTest] as true if the test will take considerable time.
-void testExample(String exampleName, String dartOutput, String? cOutput,
+void testExample(String exampleName, String dartOutput,
     {bool isLargeTest = false}) {
   test(
     'Generate and compare bindings for $exampleName',
@@ -37,30 +37,65 @@ void testExample(String exampleName, String dartOutput, String? cOutput,
   );
 }
 
+void testDartApiExample(
+    {required String exampleName,
+    required String generatorScriptPath,
+    required String outputPath,
+    bool isLargeTest = false}) {
+  test(
+    'Generate and compare bindings for $exampleName',
+    timeout: const Timeout.factor(3),
+    () async {
+      final examplePath = join('example', exampleName);
+      try {
+        final generatorResult = await Process.run(
+            Platform.resolvedExecutable, ['run', generatorScriptPath],
+            workingDirectory: examplePath);
+        if ((generatorResult.stderr as String)
+            .contains('Gradle execution failed.')) {
+          stderr.writeln('Skip: $exampleName');
+          return;
+        }
+        final processResults = await Process.run(
+            'git', ['diff', '--exit-code', outputPath],
+            workingDirectory: examplePath);
+        if (processResults.exitCode == 1) {
+          fail('The checked-in bindings of $exampleName are out of date. Run '
+              'the generator script ($generatorScriptPath) and commit the '
+              'changes.\n\n${processResults.stdout}');
+        } else if (processResults.exitCode != 0) {
+          throw Exception(
+              'Invocation of "git diff" failed:\n${processResults.stderr}');
+        }
+      } on GradleException catch (_) {
+        stderr.writeln('Skip: $exampleName');
+      }
+    },
+    tags: isLargeTest ? largeTestTag : null,
+  );
+}
+
 void main() async {
   await checkLocallyBuiltDependencies();
-  testExample(
-    'in_app_java',
-    join('lib', 'android_utils.dart'),
-    join('src', 'android_utils'),
+  testDartApiExample(
+    exampleName: 'in_app_java',
+    generatorScriptPath: 'tool/jnigen.dart',
+    outputPath: join('lib', 'android_utils.g.dart'),
     isLargeTest: true,
   );
   testExample(
     'pdfbox_plugin',
     join('lib', 'src', 'third_party'),
-    'src',
     isLargeTest: false,
   );
   testExample(
     'notification_plugin',
     join('lib', 'notifications.dart'),
-    'src',
     isLargeTest: true,
   );
   testExample(
     'kotlin_plugin',
     join('lib', 'kotlin_bindings.dart'),
-    'src',
     isLargeTest: true,
   );
 }