[jnigen] standardize on using gradle to build all artifacts versus a mix of Maven and Gradle

pkgs/jni/CHANGELOG.md

@@ -1,3 +1,9 @@
+## 0.14.1
+- Moved build system for Java code from Maven to Gradle.
+- Updated `bin\setup.dart` to do lookup for a Gradle wrapper executable.
+- Change eliminates the need to install Maven, all that is 
+  needed is a Java install.
+
 ## 0.14.0
 
 - Added `DynamicLibraryLoadError` which is thrown when the dynamic library fails

pkgs/jni/bin/setup.dart

@@ -22,7 +22,10 @@ const _verbose = 'verbose';
 const _cmakeArgs = 'cmake-args';
 
 Future<void> runCommand(
-    String exec, List<String> args, String workingDir) async {
+  String exec,
+  List<String> args,
+  String workingDir,
+) async {
   // For printing relative path always.
   var current = Directory.current.path;
   if (!current.endsWith(Platform.pathSeparator)) {
@@ -37,7 +40,8 @@ Future<void> runCommand(
   int status;
   if (options.verbose) {
     final process = await Process.start(
-      exec, args,
+      exec,
+      args,
       workingDirectory: workingDir,
       mode: ProcessStartMode.inheritStdio,
       // without `runInShell`, sometimes cmake doesn't run on windows.
@@ -49,8 +53,12 @@ Future<void> runCommand(
     }
   } else {
     // ProcessStartMode.normal sometimes hangs on windows. No idea why.
-    final process = await Process.run(exec, args,
-        runInShell: true, workingDirectory: workingDir);
+    final process = await Process.run(
+      exec,
+      args,
+      runInShell: true,
+      workingDirectory: workingDir,
+    );
     status = process.exitCode;
     if (status != 0) {
       exitCode = status;
@@ -144,17 +152,28 @@ String getTargetName(Directory cDir) {
 
 void main(List<String> arguments) async {
   final parser = ArgParser()
-    ..addOption(_buildPath,
-        abbr: 'b', help: 'Directory to place built artifacts')
-    ..addMultiOption(_srcPath,
-        abbr: 's', help: 'alternative path to package:jni sources')
-    ..addMultiOption(_packageName,
-        abbr: 'p',
-        help: 'package for which native'
-            'library should be built')
+    ..addOption(
+      _buildPath,
+      abbr: 'b',
+      help: 'Directory to place built artifacts',
+    )
+    ..addMultiOption(
+      _srcPath,
+      abbr: 's',
+      help: 'alternative path to package:jni sources',
+    )
+    ..addMultiOption(
+      _packageName,
+      abbr: 'p',
+      help: 'package for which native'
+          'library should be built',
+    )
     ..addFlag(_verbose, abbr: 'v', help: 'Enable verbose output')
-    ..addMultiOption(_cmakeArgs,
-        abbr: 'm', help: 'Pass additional argument to CMake');
+    ..addMultiOption(
+      _cmakeArgs,
+      abbr: 'm',
+      help: 'Pass additional argument to CMake',
+    );
   final argResults = parser.parse(arguments);
   options = Options(argResults);
   final rest = argResults.rest;
@@ -174,8 +193,10 @@ void main(List<String> arguments) async {
   }
   if (sources.isEmpty) {
     final dependencySources = await findDependencySources();
-    stderr.writeln('selecting source directories for dependencies: '
-        '${dependencySources.keys}');
+    stderr.writeln(
+      'selecting source directories for dependencies: '
+      '${dependencySources.keys}',
+    );
     sources.addAll(dependencySources.values);
   } else {
     stderr.writeln('selecting source directories: $sources');
@@ -194,17 +215,28 @@ void main(List<String> arguments) async {
 
   final javaSrc = await findSources('jni', 'java');
   final targetJar = File.fromUri(buildDir.uri.resolve('jni.jar'));
+  final isWin = Platform.isWindows;
+  verboseLog('File exists:${targetJar.existsSync()}');
+
+  final gradleWExecutable = (Platform.isLinux || Platform.isMacOS)
+      ? Uri.directory(javaSrc).resolve('gradlew')
+      : Uri.directory(javaSrc).resolve('gradlew.bat');
+
   if (!needsBuild(targetJar, Directory.fromUri(Uri.directory(javaSrc)))) {
-    verboseLog('Last modified of ${targetJar.path}: '
-        '${targetJar.lastModifiedSync()}.');
+    verboseLog(
+      'Last modified of ${targetJar.path}: '
+      '${targetJar.lastModifiedSync()}.',
+    );
     stderr.writeln('Target newer than source, skipping build.');
   } else {
-    verboseLog('Running mvn package for jni java sources to $buildPath.');
+    verboseLog('Running gradle task for building jni sources to $buildPath.');
     await runCommand(
-      'mvn',
-      ['package', '-Dtarget=${buildDir.absolute.path}'],
-      await findSources('jni', 'java'),
-    );
+        gradleWExecutable.toFilePath(windows: isWin),
+        [
+          'jar',
+          '-Pjni.targetDir=${buildDir.absolute.uri.toFilePath(windows: isWin)}',
+        ],
+        await findSources('jni', 'java'));
   }
 
   for (var srcPath in sources) {
@@ -221,8 +253,10 @@ void main(List<String> arguments) async {
     final targetFileUri = buildDir.uri.resolve(getTargetName(srcDir));
     final targetFile = File.fromUri(targetFileUri);
     if (!needsBuild(targetFile, srcDir)) {
-      verboseLog('Last modified of ${targetFile.path}: '
-          '${targetFile.lastModifiedSync()}.');
+      verboseLog(
+        'Last modified of ${targetFile.path}: '
+        '${targetFile.lastModifiedSync()}.',
+      );
       stderr.writeln('Target newer than source, skipping build.');
       continue;
     }

pkgs/jni/java/build.gradle.kts

@@ -0,0 +1,39 @@
+plugins {
+    java
+    application
+}
+
+repositories {
+    mavenCentral()
+    google()
+}
+
+dependencies {
+    implementation(libs.org.jetbrains.kotlin.kotlin.stdlib)
+    implementation(libs.org.jetbrains.kotlinx.kotlinx.coroutines.core)
+}
+
+group = "com.github.dart_lang"
+description = "jni"
+
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
+tasks.withType<Jar> {
+    val targetDir: String? = project.findProperty("jni.targetDir") as String?
+    if (targetDir != null) {
+        destinationDirectory = file(targetDir)
+    } else {
+        destinationDirectory = file("build/jni_libs")
+    }
+}
+
+tasks.withType<JavaCompile>() {
+    options.encoding = "UTF-8"
+}
+
+tasks.withType<Javadoc>() {
+    options.encoding = "UTF-8"
+}

pkgs/jni/java/gradle/libs.versions.toml

@@ -0,0 +1,10 @@
+# This file was generated by the Gradle 'init' task.
+# https://docs.gradle.org/current/userguide/platforms.html#sub::toml-dependencies-format
+
+[versions]
+org-jetbrains-kotlin-kotlin-stdlib = "1.6.20"
+org-jetbrains-kotlinx-kotlinx-coroutines-core = "1.6.4"
+
+[libraries]
+org-jetbrains-kotlin-kotlin-stdlib = { module = "org.jetbrains.kotlin:kotlin-stdlib", version.ref = "org-jetbrains-kotlin-kotlin-stdlib" }
+org-jetbrains-kotlinx-kotlinx-coroutines-core = { module = "org.jetbrains.kotlinx:kotlinx-coroutines-core", version.ref = "org-jetbrains-kotlinx-kotlinx-coroutines-core" }

pkgs/jni/java/gradle/wrapper/gradle-wrapper.properties

@@ -0,0 +1,7 @@
+distributionBase=GRADLE_USER_HOME
+distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.7-bin.zip
+networkTimeout=10000
+validateDistributionUrl=true
+zipStoreBase=GRADLE_USER_HOME
+zipStorePath=wrapper/dists