Add support for Kotlin's runApplication

Spring Boot 2.0.0.M6 offers a better integration with Kotlin. A
top-level `runApplication` function can be used to start the app and
additional dependency and plugin management are provided.

This commit simplifies the way a Kotlin-based project is generated when
running with a compatible version

Closes gh-534

initializr-generator/src/main/java/io/spring/initializr/generator/ProjectGenerator.java

@@ -80,6 +80,8 @@ public class ProjectGenerator {
 
 	private static final Version VERSION_2_0_0_M3 = Version.parse("2.0.0.M3");
 
+	private static final Version VERSION_2_0_0_M6 = Version.parse("2.0.0.M6");
+
 	@Autowired
 	private ApplicationEventPublisher eventPublisher;
 
@@ -344,7 +346,16 @@ public class ProjectGenerator {
 			model.put("war", true);
 		}
 
+		// Kotlin supported as of M6
+		final boolean kotlinSupport = VERSION_2_0_0_M6
+				.compareTo(Version.safeParse(request.getBootVersion())) <= 0;
+		model.put("kotlinSupport", kotlinSupport);
+
 		if (isMavenBuild(request)) {
+			if (kotlinSupport) { // No need to provide a kotlin.version
+				request.getBuildProperties().getVersions()
+						.remove(new VersionProperty("kotlin.version"));
+			}
 			model.put("mavenBuild", true);
 			ParentPom parentPom = metadata.getConfiguration().getEnv().getMaven()
 					.resolveParentPom(request.getBootVersion());
@@ -433,8 +444,8 @@ public class ProjectGenerator {
 		model.put("newTestInfrastructure", isNewTestInfrastructureAvailable(request));
 
 		// Servlet Initializer
-		model.put("servletInitializrImport", generateImport(getServletInitializrClass(request),
+		model.put("servletInitializrImport", new Imports(request.getLanguage()).add(
-				request.getLanguage()));
+				getServletInitializrClass(request)).toString());
 
 		// Java versions
 		model.put("isJava6", isJavaVersion(request, "1.6"));
@@ -538,17 +549,6 @@ public class ProjectGenerator {
 		}
 	}
 
-	protected String addImport(String type, String language) {
-		return String.format("%s%n", generateImport(type, language));
-	}
-
-	protected String generateImport(String type, String language) {
-		String end = ("groovy".equals(language) || "kotlin".equals(language)) ? "" : ";";
-		return "import " + type + end;
-	}
-
-
-
 	private static boolean isGradleBuild(ProjectRequest request) {
 		return "gradle".equals(request.getBuild());
 	}

initializr-generator/src/main/resources/templates/Application.kt

@@ -1,11 +1,21 @@
 package {{packageName}}
 
+{{^kotlinSupport}}
 import org.springframework.boot.SpringApplication
+{{/kotlinSupport}}
 {{applicationImports}}
+{{#kotlinSupport}}
+import org.springframework.boot.runApplication
+{{/kotlinSupport}}
 
 {{applicationAnnotations}}
 class {{applicationName}}
 
 fun main(args: Array<String>) {
+{{^kotlinSupport}}
     SpringApplication.run({{applicationName}}::class.java, *args)
+{{/kotlinSupport}}
+{{#kotlinSupport}}
+    runApplication<{{applicationName}}>(*args)
+{{/kotlinSupport}}
 }

initializr-generator/src/main/resources/templates/starter-build.gradle

@@ -87,12 +87,12 @@ dependencies {
 	compile("org.jetbrains.kotlin:kotlin-stdlib:${kotlinVersion}")
 	{{/isJava6}}
 	{{#isJava7}}
-	compile("org.jetbrains.kotlin:kotlin-stdlib-jre7:${kotlinVersion}")
+	compile("org.jetbrains.kotlin:kotlin-stdlib-jre7{{^kotlinSupport}}:${kotlinVersion}{{/kotlinSupport}}")
 	{{/isJava7}}
 	{{#isJava8}}
-	compile("org.jetbrains.kotlin:kotlin-stdlib-jre8:${kotlinVersion}")
+	compile("org.jetbrains.kotlin:kotlin-stdlib-jre8{{^kotlinSupport}}:${kotlinVersion}{{/kotlinSupport}}")
 	{{/isJava8}}
-	compile("org.jetbrains.kotlin:kotlin-reflect:${kotlinVersion}")
+	compile("org.jetbrains.kotlin:kotlin-reflect{{^kotlinSupport}}:${kotlinVersion}{{/kotlinSupport}}")
 	{{/kotlin}}
 	{{#runtimeDependencies}}
 	runtime('{{groupId}}:{{artifactId}}{{#version}}:{{version}}{{/version}}{{#type}}@{{type}}{{/type}}')

initializr-generator/src/main/resources/templates/starter-pom.xml

@@ -58,12 +58,16 @@
 			{{#isJava8}}
 			<artifactId>kotlin-stdlib-jre8</artifactId>
 			{{/isJava8}}
+			{{^kotlinSupport}}
 			<version>${kotlin.version}</version>
+			{{/kotlinSupport}}
 		</dependency>
 		<dependency>
 			<groupId>org.jetbrains.kotlin</groupId>
 			<artifactId>kotlin-reflect</artifactId>
+			{{^kotlinSupport}}
 			<version>${kotlin.version}</version>
+			{{/kotlinSupport}}
 		</dependency>
 		{{/kotlin}}
 
@@ -177,15 +181,20 @@
 			<plugin>
 				<artifactId>kotlin-maven-plugin</artifactId>
 				<groupId>org.jetbrains.kotlin</groupId>
+				{{^kotlinSupport}}
 				<version>${kotlin.version}</version>
+				{{/kotlinSupport}}
 				<configuration>
 					<compilerPlugins>
 						<plugin>spring</plugin>
 					</compilerPlugins>
+					{{^kotlinSupport}}
 					{{#isJava8}}
 					<jvmTarget>1.8</jvmTarget>
 					{{/isJava8}}
+					{{/kotlinSupport}}
 				</configuration>
+				{{^kotlinSupport}}
 				<executions>
 					<execution>
 						<id>compile</id>
@@ -202,6 +211,7 @@
 						</goals>
 					</execution>
 				</executions>
+				{{/kotlinSupport}}
 				<dependencies>
 					<dependency>
 						<groupId>org.jetbrains.kotlin</groupId>

initializr-generator/src/test/java/io/spring/initializr/generator/ProjectGeneratorBuildTests.java

@@ -191,6 +191,30 @@ public class ProjectGeneratorBuildTests extends AbstractProjectGeneratorTests {
 				"project/" + build + "/kotlin-java7-" + assertFileName));
 	}
 
+	@Test
+	public void kotlinSpringBoot2Legacy() {
+		ProjectRequest request = createProjectRequest();
+		request.setLanguage("kotlin");
+		request.setBootVersion("2.0.0.M5");
+		ProjectAssert project = generateProject(request);
+		project.sourceCodeAssert("src/main/kotlin/com/example/demo/DemoApplication.kt")
+				.equalsTo(new ClassPathResource("project/kotlin/spring-boot-2.0/DemoApplicationLegacy.kt.gen"));
+		project.sourceCodeAssert(fileName).equalsTo(new ClassPathResource(
+				"project/" + build + "/kotlin-springboot2-legacy-" + assertFileName));
+	}
+
+	@Test
+	public void kotlinSpringBoot2() {
+		ProjectRequest request = createProjectRequest();
+		request.setLanguage("kotlin");
+		request.setBootVersion("2.0.0.M6");
+		ProjectAssert project = generateProject(request);
+		project.sourceCodeAssert("src/main/kotlin/com/example/demo/DemoApplication.kt")
+				.equalsTo(new ClassPathResource("project/kotlin/spring-boot-2.0/DemoApplication.kt.gen"));
+		project.sourceCodeAssert(fileName).equalsTo(new ClassPathResource(
+				"project/" + build + "/kotlin-springboot2-" + assertFileName));
+	}
+
 	@Override
 	public ProjectRequest createProjectRequest(String... styles) {
 		ProjectRequest request = super.createProjectRequest(styles);

initializr-generator/src/test/resources/project/gradle/kotlin-springboot2-build.gradle.gen

@@ -0,0 +1,46 @@
+buildscript {
+	ext {
+		kotlinVersion = '1.1.1'
+		springBootVersion = '2.0.0.M6'
+	}
+	repositories {
+		mavenCentral()
+		maven { url "https://repo.spring.io/snapshot" }
+		maven { url "https://repo.spring.io/milestone" }
+	}
+	dependencies {
+		classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
+		classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${kotlinVersion}")
+		classpath("org.jetbrains.kotlin:kotlin-allopen:${kotlinVersion}")
+	}
+}
+
+apply plugin: 'kotlin'
+apply plugin: 'kotlin-spring'
+apply plugin: 'eclipse'
+apply plugin: 'org.springframework.boot'
+apply plugin: 'io.spring.dependency-management'
+
+group = 'com.example'
+version = '0.0.1-SNAPSHOT'
+sourceCompatibility = 1.8
+compileKotlin {
+	kotlinOptions.jvmTarget = "1.8"
+}
+compileTestKotlin {
+	kotlinOptions.jvmTarget = "1.8"
+}
+
+repositories {
+	mavenCentral()
+	maven { url "https://repo.spring.io/snapshot" }
+	maven { url "https://repo.spring.io/milestone" }
+}
+
+
+dependencies {
+	compile('org.springframework.boot:spring-boot-starter')
+	compile("org.jetbrains.kotlin:kotlin-stdlib-jre8")
+	compile("org.jetbrains.kotlin:kotlin-reflect")
+	testCompile('org.springframework.boot:spring-boot-starter-test')
+}

initializr-generator/src/test/resources/project/gradle/kotlin-springboot2-legacy-build.gradle.gen

@@ -0,0 +1,46 @@
+buildscript {
+	ext {
+		kotlinVersion = '1.1.1'
+		springBootVersion = '2.0.0.M5'
+	}
+	repositories {
+		mavenCentral()
+		maven { url "https://repo.spring.io/snapshot" }
+		maven { url "https://repo.spring.io/milestone" }
+	}
+	dependencies {
+		classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
+		classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:${kotlinVersion}")
+		classpath("org.jetbrains.kotlin:kotlin-allopen:${kotlinVersion}")
+	}
+}
+
+apply plugin: 'kotlin'
+apply plugin: 'kotlin-spring'
+apply plugin: 'eclipse'
+apply plugin: 'org.springframework.boot'
+apply plugin: 'io.spring.dependency-management'
+
+group = 'com.example'
+version = '0.0.1-SNAPSHOT'
+sourceCompatibility = 1.8
+compileKotlin {
+	kotlinOptions.jvmTarget = "1.8"
+}
+compileTestKotlin {
+	kotlinOptions.jvmTarget = "1.8"
+}
+
+repositories {
+	mavenCentral()
+	maven { url "https://repo.spring.io/snapshot" }
+	maven { url "https://repo.spring.io/milestone" }
+}
+
+
+dependencies {
+	compile('org.springframework.boot:spring-boot-starter')
+	compile("org.jetbrains.kotlin:kotlin-stdlib-jre8:${kotlinVersion}")
+	compile("org.jetbrains.kotlin:kotlin-reflect:${kotlinVersion}")
+	testCompile('org.springframework.boot:spring-boot-starter-test')
+}

initializr-generator/src/test/resources/project/kotlin/spring-boot-2.0/DemoApplication.kt.gen

@@ -0,0 +1,11 @@
+package com.example.demo
+
+import org.springframework.boot.autoconfigure.SpringBootApplication
+import org.springframework.boot.runApplication
+
+@SpringBootApplication
+class DemoApplication
+
+fun main(args: Array<String>) {
+    runApplication<DemoApplication>(*args)
+}

initializr-generator/src/test/resources/project/kotlin/spring-boot-2.0/DemoApplicationLegacy.kt.gen

@@ -0,0 +1,11 @@
+package com.example.demo
+
+import org.springframework.boot.SpringApplication
+import org.springframework.boot.autoconfigure.SpringBootApplication
+
+@SpringBootApplication
+class DemoApplication
+
+fun main(args: Array<String>) {
+    SpringApplication.run(DemoApplication::class.java, *args)
+}

initializr-generator/src/test/resources/project/maven/kotlin-springboot2-legacy-pom.xml.gen

@@ -0,0 +1,136 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<groupId>com.example</groupId>
+	<artifactId>demo</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+
+	<name>demo</name>
+	<description>Demo project for Spring Boot</description>
+
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.0.0.M5</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+
+	<properties>
+		<kotlin.compiler.incremental>true</kotlin.compiler.incremental>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+		<kotlin.version>1.1.1</kotlin.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.jetbrains.kotlin</groupId>
+			<artifactId>kotlin-stdlib-jre8</artifactId>
+			<version>${kotlin.version}</version>
+		</dependency>
+		<dependency>
+			<groupId>org.jetbrains.kotlin</groupId>
+			<artifactId>kotlin-reflect</artifactId>
+			<version>${kotlin.version}</version>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
+		<testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+			<plugin>
+				<artifactId>kotlin-maven-plugin</artifactId>
+				<groupId>org.jetbrains.kotlin</groupId>
+				<version>${kotlin.version}</version>
+				<configuration>
+					<compilerPlugins>
+						<plugin>spring</plugin>
+					</compilerPlugins>
+					<jvmTarget>1.8</jvmTarget>
+				</configuration>
+				<executions>
+					<execution>
+						<id>compile</id>
+						<phase>compile</phase>
+						<goals>
+							<goal>compile</goal>
+						</goals>
+					</execution>
+					<execution>
+						<id>test-compile</id>
+						<phase>test-compile</phase>
+						<goals>
+							<goal>test-compile</goal>
+						</goals>
+					</execution>
+				</executions>
+				<dependencies>
+					<dependency>
+						<groupId>org.jetbrains.kotlin</groupId>
+						<artifactId>kotlin-maven-allopen</artifactId>
+						<version>${kotlin.version}</version>
+					</dependency>
+				</dependencies>
+			</plugin>
+		</plugins>
+	</build>
+
+	<repositories>
+		<repository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+		</repository>
+		<repository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+	</repositories>
+
+	<pluginRepositories>
+		<pluginRepository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+		</pluginRepository>
+		<pluginRepository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+	</pluginRepositories>
+
+
+</project>

initializr-generator/src/test/resources/project/maven/kotlin-springboot2-pom.xml.gen

@@ -0,0 +1,115 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+
+	<groupId>com.example</groupId>
+	<artifactId>demo</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+	<packaging>jar</packaging>
+
+	<name>demo</name>
+	<description>Demo project for Spring Boot</description>
+
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.0.0.M6</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+
+	<properties>
+		<kotlin.compiler.incremental>true</kotlin.compiler.incremental>
+		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+		<java.version>1.8</java.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.jetbrains.kotlin</groupId>
+			<artifactId>kotlin-stdlib-jre8</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.jetbrains.kotlin</groupId>
+			<artifactId>kotlin-reflect</artifactId>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<sourceDirectory>${project.basedir}/src/main/kotlin</sourceDirectory>
+		<testSourceDirectory>${project.basedir}/src/test/kotlin</testSourceDirectory>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+			<plugin>
+				<artifactId>kotlin-maven-plugin</artifactId>
+				<groupId>org.jetbrains.kotlin</groupId>
+				<configuration>
+					<compilerPlugins>
+						<plugin>spring</plugin>
+					</compilerPlugins>
+				</configuration>
+				<dependencies>
+					<dependency>
+						<groupId>org.jetbrains.kotlin</groupId>
+						<artifactId>kotlin-maven-allopen</artifactId>
+						<version>${kotlin.version}</version>
+					</dependency>
+				</dependencies>
+			</plugin>
+		</plugins>
+	</build>
+
+	<repositories>
+		<repository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+		</repository>
+		<repository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+	</repositories>
+
+	<pluginRepositories>
+		<pluginRepository>
+			<id>spring-snapshots</id>
+			<name>Spring Snapshots</name>
+			<url>https://repo.spring.io/snapshot</url>
+			<snapshots>
+				<enabled>true</enabled>
+			</snapshots>
+		</pluginRepository>
+		<pluginRepository>
+			<id>spring-milestones</id>
+			<name>Spring Milestones</name>
+			<url>https://repo.spring.io/milestone</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+	</pluginRepositories>
+
+
+</project>