Apply the Kotlin plugin in a java project (#95225)

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

@@ -19,7 +19,17 @@ import '../project.dart';
 import '../reporting/reporting.dart';
 import 'android_sdk.dart';
 
-const String _defaultGradleVersion = '6.7';
+// These are the versions used in the project templates.
+//
+// In general, Flutter aims to default to the latest version.
+// However, this currently requires to migrate existing integration tests to the latest supported values.
+//
+// For more information about the latest version, check:
+// https://developer.android.com/studio/releases/gradle-plugin#updating-gradle
+// https://kotlinlang.org/docs/gradle.html#plugin-and-versions
+const String templateDefaultGradleVersion = '6.7';
+const String templateAndroidGradlePluginVersion = '4.1.0';
+const String templateKotlinGradlePluginVersion = '1.4.32';
 
 final RegExp _androidPluginRegExp = RegExp(r'com\.android\.tools\.build:gradle:(\d+\.\d+\.\d+)');
 
@@ -109,14 +119,14 @@ distributionUrl=https\\://services.gradle.org/distributions/gradle-$gradleVersio
 String getGradleVersionForAndroidPlugin(Directory directory, Logger logger) {
   final File buildFile = directory.childFile('build.gradle');
   if (!buildFile.existsSync()) {
-    logger.printTrace("$buildFile doesn't exist, assuming AGP version: $_defaultGradleVersion");
-    return _defaultGradleVersion;
+    logger.printTrace("$buildFile doesn't exist, assuming Gradle version: $templateDefaultGradleVersion");
+    return templateDefaultGradleVersion;
   }
   final String buildFileContent = buildFile.readAsStringSync();
   final Iterable<Match> pluginMatches = _androidPluginRegExp.allMatches(buildFileContent);
   if (pluginMatches.isEmpty) {
-    logger.printTrace("$buildFile doesn't provide an AGP version, assuming AGP version: $_defaultGradleVersion");
-    return _defaultGradleVersion;
+    logger.printTrace("$buildFile doesn't provide an AGP version, assuming Gradle version: $templateDefaultGradleVersion");
+    return templateDefaultGradleVersion;
   }
   final String? androidPluginVersion = pluginMatches.first.group(1);
   logger.printTrace('$buildFile provides AGP version: $androidPluginVersion');

packages/flutter_tools/lib/src/commands/create.dart

@@ -271,6 +271,9 @@ class CreateCommand extends CreateBase {
       // Enable null safety everywhere.
       dartSdkVersionBounds: '">=$dartSdk <3.0.0"',
       implementationTests: boolArg('implementation-tests'),
+      agpVersion: gradle.templateAndroidGradlePluginVersion,
+      kotlinVersion: gradle.templateKotlinGradlePluginVersion,
+      gradleVersion: gradle.templateDefaultGradleVersion,
     );
 
     final String relativeDirPath = globals.fs.path.relative(projectDirPath);

packages/flutter_tools/lib/src/commands/create_base.dart

@@ -336,6 +336,9 @@ abstract class CreateBase extends FlutterCommand {
     String iosLanguage,
     String flutterRoot,
     String dartSdkVersionBounds,
+    String agpVersion,
+    String kotlinVersion,
+    String gradleVersion,
     bool withPluginHook = false,
     bool ios = false,
     bool android = false,
@@ -398,6 +401,9 @@ abstract class CreateBase extends FlutterCommand {
       'year': DateTime.now().year,
       'dartSdkVersionBounds': dartSdkVersionBounds,
       'implementationTests': implementationTests,
+      'agpVersion': agpVersion,
+      'kotlinVersion': kotlinVersion,
+      'gradleVersion': gradleVersion,
     };
   }
 

packages/flutter_tools/lib/src/project.dart

@@ -543,6 +543,9 @@ class AndroidProject extends FlutterProjectPlatform {
         'projectName': parent.manifest.appName,
         'androidIdentifier': androidIdentifier,
         'androidX': usesAndroidX,
+        'agpVersion': gradle.templateAndroidGradlePluginVersion,
+        'kotlinVersion': gradle.templateKotlinGradlePluginVersion,
+        'gradleVersion': gradle.templateDefaultGradleVersion,
       },
       printStatusWhenWriting: false,
     );

packages/flutter_tools/templates/app_shared/android-java.tmpl/app/build.gradle.tmpl

@@ -22,6 +22,7 @@ if (flutterVersionName == null) {
 }
 
 apply plugin: 'com.android.application'
+apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {

packages/flutter_tools/templates/app_shared/android-kotlin.tmpl/build.gradle → packages/flutter_tools/templates/app_shared/android-java.tmpl/build.gradle.tmpl

 buildscript {
-    ext.kotlin_version = '1.4.32'
+    ext.kotlin_version = '{{kotlinVersion}}'
     repositories {
         google()
         mavenCentral()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.1.0'
+        classpath 'com.android.tools.build:gradle:{{agpVersion}}'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }

packages/flutter_tools/templates/app_shared/android-java.tmpl/build.gradle → packages/flutter_tools/templates/app_shared/android-kotlin.tmpl/build.gradle.tmpl

 buildscript {
+    ext.kotlin_version = '{{kotlinVersion}}'
     repositories {
         google()
         mavenCentral()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.1.0'
+        classpath 'com.android.tools.build:gradle:{{agpVersion}}'
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
 

packages/flutter_tools/templates/app_shared/android.tmpl/gradle/wrapper/gradle-wrapper.properties → packages/flutter_tools/templates/app_shared/android.tmpl/gradle/wrapper/gradle-wrapper.properties.tmpl

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.7-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-{{gradleVersion}}-all.zip

packages/flutter_tools/templates/module/android/gradle/build.gradle.copy.tmpl → packages/flutter_tools/templates/module/android/gradle/build.gradle.tmpl

@@ -7,7 +7,7 @@ buildscript {
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.1.0'
+        classpath 'com.android.tools.build:gradle:{{agpVersion}}'
     }
 }
 

packages/flutter_tools/templates/plugin/android-kotlin.tmpl/build.gradle.tmpl

@@ -2,14 +2,14 @@ group '{{androidIdentifier}}'
 version '1.0-SNAPSHOT'
 
 buildscript {
-    ext.kotlin_version = '1.4.32'
+    ext.kotlin_version = '{{kotlinVersion}}'
     repositories {
         google()
         mavenCentral()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.1.0'
+        classpath 'com.android.tools.build:gradle:{{agpVersion}}'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }

packages/flutter_tools/templates/template_manifest.json

@@ -18,11 +18,11 @@
         "templates/app_shared/analysis_options.yaml.tmpl",
         "templates/app_shared/android-java.tmpl/app/build.gradle.tmpl",
         "templates/app_shared/android-java.tmpl/app/src/main/java/androidIdentifier/MainActivity.java.tmpl",
-        "templates/app_shared/android-java.tmpl/build.gradle",
+        "templates/app_shared/android-java.tmpl/build.gradle.tmpl",
         "templates/app_shared/android-java.tmpl/projectName_android.iml.tmpl",
         "templates/app_shared/android-kotlin.tmpl/app/build.gradle.tmpl",
         "templates/app_shared/android-kotlin.tmpl/app/src/main/kotlin/androidIdentifier/MainActivity.kt.tmpl",
-        "templates/app_shared/android-kotlin.tmpl/build.gradle",
+        "templates/app_shared/android-kotlin.tmpl/build.gradle.tmpl",
         "templates/app_shared/android-kotlin.tmpl/projectName_android.iml.tmpl",
         "templates/app_shared/android.tmpl/.gitignore",
         "templates/app_shared/android.tmpl/app/src/debug/AndroidManifest.xml.tmpl",
@@ -38,7 +38,7 @@
         "templates/app_shared/android.tmpl/app/src/main/res/values/styles.xml",
         "templates/app_shared/android.tmpl/app/src/profile/AndroidManifest.xml.tmpl",
         "templates/app_shared/android.tmpl/gradle.properties.tmpl",
-        "templates/app_shared/android.tmpl/gradle/wrapper/gradle-wrapper.properties",
+        "templates/app_shared/android.tmpl/gradle/wrapper/gradle-wrapper.properties.tmpl",
         "templates/app_shared/android.tmpl/settings.gradle",
         "templates/app_shared/ios-objc.tmpl/Runner.xcodeproj/project.pbxproj.tmpl",
         "templates/app_shared/ios-objc.tmpl/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme",
@@ -207,7 +207,7 @@
 
         "templates/module/android/deferred_component/build.gradle.tmpl",
         "templates/module/android/deferred_component/src/main/AndroidManifest.xml.tmpl",
-        "templates/module/android/gradle/build.gradle.copy.tmpl",
+        "templates/module/android/gradle/build.gradle.tmpl",
         "templates/module/android/gradle/gradle.properties.tmpl",
         "templates/module/android/host_app_common/app.tmpl/build.gradle.tmpl",
         "templates/module/android/host_app_common/app.tmpl/src/main/AndroidManifest.xml.tmpl",