[flutter_tools] Add namespace getter in Android project; use namespace as fallback (#121416)

[flutter_tools] Add namespace getter in Android project; use namespace as fallback

packages/flutter_tools/lib/src/android/application_package.dart

@@ -171,7 +171,10 @@ class AndroidApk extends ApplicationPackage implements PrebuiltApplicationPackag
       logger.printError('Please check ${manifest.path} for errors.');
       return null;
     }
-    final String? packageId = manifests.first.getAttribute('package');
+
+    // Starting from AGP version 7.3, the `package` attribute in Manifest.xml
+    // can be replaced with the `namespace` attribute under the `android` section in `android/app/build.gradle`.
+    final String? packageId = manifests.first.getAttribute('package') ?? androidProject.namespace;
 
     String? launchActivity;
     for (final XmlElement activity in document.findAllElements('activity')) {

packages/flutter_tools/lib/src/project.dart

@@ -424,6 +424,7 @@ class AndroidProject extends FlutterProjectPlatform {
   @override
   String get pluginConfigKey => AndroidPlugin.kConfigKey;
 
+  static final RegExp _androidNamespacePattern = RegExp('android {[\\S\\s]+namespace[\\s]+[\'"](.+)[\'"]');
   static final RegExp _applicationIdPattern = RegExp('^\\s*applicationId\\s+[\'"](.*)[\'"]\\s*\$');
   static final RegExp _kotlinPluginPattern = RegExp('^\\s*apply plugin\\:\\s+[\'"]kotlin-android[\'"]\\s*\$');
   static final RegExp _groupPattern = RegExp('^\\s*group\\s+[\'"](.*)[\'"]\\s*\$');
@@ -486,9 +487,15 @@ class AndroidProject extends FlutterProjectPlatform {
   }
 
   File get appManifestFile {
-    return isUsingGradle
-        ? globals.fs.file(globals.fs.path.join(hostAppGradleRoot.path, 'app', 'src', 'main', 'AndroidManifest.xml'))
-        : hostAppGradleRoot.childFile('AndroidManifest.xml');
+    if(isUsingGradle) {
+      return hostAppGradleRoot
+        .childDirectory('app')
+        .childDirectory('src')
+        .childDirectory('main')
+        .childFile('AndroidManifest.xml');
+    }
+
+    return hostAppGradleRoot.childFile('AndroidManifest.xml');
   }
 
   File get gradleAppOutV1File => gradleAppOutV1Directory.childFile('app-debug.apk');
@@ -512,6 +519,19 @@ class AndroidProject extends FlutterProjectPlatform {
     return firstMatchInFile(gradleFile, _applicationIdPattern)?.group(1);
   }
 
+  /// Get the namespace for newer Android projects,
+  /// which replaces the `package` attribute in the Manifest.xml.
+  String? get namespace {
+    final File gradleFile = hostAppGradleRoot.childDirectory('app').childFile('build.gradle');
+
+    if (!gradleFile.existsSync()) {
+      return null;
+    }
+
+    // firstMatchInFile() reads per line but `_androidNamespacePattern` matches a multiline pattern.
+    return _androidNamespacePattern.firstMatch(gradleFile.readAsStringSync())?.group(1);
+  }
+
   String? get group {
     final File gradleFile = hostAppGradleRoot.childFile('build.gradle');
     return firstMatchInFile(gradleFile, _groupPattern)?.group(1);

packages/flutter_tools/test/general.shard/android/android_gradle_builder_test.dart

@@ -5,7 +5,9 @@
 import 'package:archive/archive.dart';
 import 'package:file/memory.dart';
 import 'package:file_testing/file_testing.dart';
+import 'package:flutter_tools/src/android/android_sdk.dart';
 import 'package:flutter_tools/src/android/android_studio.dart';
+import 'package:flutter_tools/src/android/application_package.dart';
 import 'package:flutter_tools/src/android/gradle.dart';
 import 'package:flutter_tools/src/android/gradle_errors.dart';
 import 'package:flutter_tools/src/android/gradle_utils.dart';
@@ -14,6 +16,8 @@ import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/base/io.dart';
 import 'package:flutter_tools/src/base/logger.dart';
 import 'package:flutter_tools/src/base/platform.dart';
+import 'package:flutter_tools/src/base/process.dart';
+import 'package:flutter_tools/src/base/user_messages.dart';
 import 'package:flutter_tools/src/build_info.dart';
 import 'package:flutter_tools/src/cache.dart';
 import 'package:flutter_tools/src/project.dart';
@@ -23,6 +27,7 @@ import 'package:test/fake.dart';
 import '../../src/common.dart';
 import '../../src/context.dart';
 import '../../src/fake_process_manager.dart';
+import '../../src/fakes.dart';
 
 void main() {
   group('gradle build', () {
@@ -724,6 +729,64 @@ void main() {
       AndroidStudio: () => FakeAndroidStudio(),
     });
 
+    testUsingContext('Uses namespace attribute if manifest lacks a package attribute', () async {
+      final FlutterProject project = FlutterProject.fromDirectoryTest(fileSystem.currentDirectory);
+      final AndroidSdk sdk = FakeAndroidSdk();
+
+      fileSystem.directory(project.android.hostAppGradleRoot)
+        .childFile('build.gradle')
+        .createSync(recursive: true);
+
+      fileSystem.directory(project.android.hostAppGradleRoot)
+        .childDirectory('app')
+        .childFile('build.gradle')
+        ..createSync(recursive: true)
+        ..writeAsStringSync(
+'''
+apply from: irrelevant/flutter.gradle
+
+android {
+    namespace 'com.example.foo'
+}
+''');
+
+      fileSystem.directory(project.android.hostAppGradleRoot)
+        .childDirectory('app')
+        .childDirectory('src')
+        .childDirectory('main')
+        .childFile('AndroidManifest.xml')
+        ..createSync(recursive: true)
+        ..writeAsStringSync(r'''
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <application
+        android:label="namespacetest"
+        android:name="${applicationName}"
+        android:icon="@mipmap/ic_launcher">
+        <activity
+            android:name=".MainActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN"/>
+                <category android:name="android.intent.category.LAUNCHER"/>
+            </intent-filter>
+        </activity>
+    </application>
+</manifest>
+''');
+
+      final AndroidApk? androidApk = await AndroidApk.fromAndroidProject(
+        project.android,
+        androidSdk: sdk,
+        fileSystem: fileSystem,
+        logger: logger,
+        processManager: processManager,
+        processUtils: ProcessUtils(processManager: processManager, logger: logger),
+        userMessages: UserMessages(),
+        buildInfo: const BuildInfo(BuildMode.debug, null, treeShakeIcons: false),
+      );
+
+      expect(androidApk?.id, 'com.example.foo');
+    });
+
     testUsingContext("doesn't indicate how to consume an AAR when printHowToConsumeAar is false", () async {
       final AndroidGradleBuilder builder = AndroidGradleBuilder(
         logger: logger,