Add Kotlin extensions for bean registration and retrieval

Issue: SPR-15048

build.gradle

@@ -326,7 +326,7 @@ project("spring-build-src") {
 project("spring-core") {
 	description = "Spring Core"
 
-	// Kotlin compiler does not support JDK 9 yet
+	// Kotlin compiler does not support JDK 9 yet, see https://youtrack.jetbrains.com/issue/KT-14988
 	if (!JavaVersion.current().java9Compatible) {
 		apply plugin: "kotlin"
 	}
@@ -430,7 +430,7 @@ project("spring-core") {
 project("spring-beans") {
 	description = "Spring Beans"
 
-	// Kotlin compiler does not support JDK 9 yet
+	// Kotlin compiler does not support JDK 9 yet, see https://youtrack.jetbrains.com/issue/KT-14988
 	if (!JavaVersion.current().java9Compatible) {
 		apply plugin: "kotlin"
 	}
@@ -514,6 +514,10 @@ project("spring-context") {
 	description = "Spring Context"
 
 	apply plugin: "groovy"
+	// Kotlin compiler does not support JDK 9 yet, see https://youtrack.jetbrains.com/issue/KT-14988
+	if (!JavaVersion.current().java9Compatible) {
+		apply plugin: "kotlin"
+	}
 
 	dependencies {
 		compile(project(":spring-aop"))
@@ -536,6 +540,7 @@ project("spring-context") {
 		optional("org.aspectj:aspectjweaver:${aspectjVersion}")
 		optional("org.codehaus.groovy:groovy-all:${groovyVersion}")
 		optional("org.beanshell:bsh:2.0b4")
+		optional("org.jetbrains.kotlin:kotlin-stdlib:${kotlinVersion}")
 		testCompile("org.apache.commons:commons-pool2:2.4.2")
 		testCompile("org.slf4j:slf4j-api:${slf4jVersion}")
 		testCompile("javax.inject:javax.inject-tck:1")
@@ -581,7 +586,7 @@ project("spring-oxm") {
 project("spring-messaging") {
 	description = "Spring Messaging"
 
-	// Kotlin compiler does not support JDK 9 yet
+	// Kotlin compiler does not support JDK 9 yet, see https://youtrack.jetbrains.com/issue/KT-14988
 	if (!JavaVersion.current().java9Compatible) {
 		apply plugin: "kotlin"
 	}
@@ -726,7 +731,7 @@ project("spring-context-indexer") {
 project("spring-web") {
 	description = "Spring Web"
 
-	// Kotlin compiler does not support JDK 9 yet
+	// Kotlin compiler does not support JDK 9 yet, see https://youtrack.jetbrains.com/issue/KT-14988
 	if (!JavaVersion.current().java9Compatible) {
 		apply plugin: "kotlin"
 	}
@@ -819,7 +824,7 @@ project("spring-web") {
 project("spring-web-reactive") {
 	description = "Spring Web Reactive"
 
-	// Kotlin compiler does not support JDK 9 yet
+	// Kotlin compiler does not support JDK 9 yet, see https://youtrack.jetbrains.com/issue/KT-14988
 	if (!JavaVersion.current().java9Compatible) {
 		apply plugin: "kotlin"
 	}

spring-beans/src/main/kotlin/org/springframework/beans/factory/BeanFactoryExtension.kt

@@ -0,0 +1,29 @@
+package org.springframework.beans.factory
+
+import kotlin.reflect.KClass
+
+/**
+ * Extension for [BeanFactory] providing [KClass] based API.
+ *
+ * @since 5.0
+ */
+object BeanFactoryExtension {
+
+	/**
+	 * @see BeanFactory.getBean(Class<T>)
+	 */
+	fun <T : Any> BeanFactory.getBean(requiredType: KClass<T>) = getBean(requiredType.java)
+
+	/**
+	 * @see BeanFactory.getBean(String, Class<T>)
+	 */
+	fun <T : Any> BeanFactory.getBean(name: String, requiredType: KClass<T>) =
+			getBean(name, requiredType.java)
+
+	/**
+	 * @see BeanFactory.getBean(Class<T>, Object...)
+	 */
+	fun <T : Any> BeanFactory.getBean(requiredType: KClass<T>, vararg args:Any) =
+			getBean(requiredType.java, *args)
+
+}

spring-beans/src/main/kotlin/org/springframework/beans/factory/ListableBeanFactoryExtension.kt

@@ -0,0 +1,56 @@
+package org.springframework.beans.factory
+
+import kotlin.reflect.KClass
+
+/**
+ * Extension for [ListableBeanFactory] providing [KClass] based API.
+ *
+ * @since 5.0
+ */
+object ListableBeanFactoryExtension {
+
+	/**
+	 * @see ListableBeanFactory.getBeanNamesForType(Class<?>)
+	 */
+	fun <T : Any> ListableBeanFactory.getBeanNamesForType(type: KClass<T>) =
+			getBeanNamesForType(type.java)
+
+	/**
+	 * @see ListableBeanFactory.getBeanNamesForType(Class<?>, boolean, boolean)
+	 */
+	fun <T : Any> ListableBeanFactory.getBeanNamesForType(type: KClass<T>,
+			includeNonSingletons: Boolean, allowEagerInit: Boolean) =
+					getBeanNamesForType(type.java, includeNonSingletons, allowEagerInit)
+
+	/**
+	 * @see ListableBeanFactory.getBeansOfType(Class<T>)
+	 */
+	fun <T : Any> ListableBeanFactory.getBeansOfType(type: KClass<T>) =
+			getBeansOfType(type.java)
+
+	/**
+	 * @see ListableBeanFactory.getBeansOfType(Class<T>, boolean, boolean)
+	 */
+	fun <T : Any> ListableBeanFactory.getBeansOfType(type: KClass<T>,
+			includeNonSingletons: Boolean, allowEagerInit: Boolean) =
+					getBeansOfType(type.java, includeNonSingletons, allowEagerInit)
+
+	/**
+	 * @see ListableBeanFactory.getBeanNamesForAnnotation
+	 */
+	fun <T : Annotation> ListableBeanFactory.getBeanNamesForAnnotation(type: KClass<T>) =
+			getBeanNamesForAnnotation(type.java)
+
+	/**
+	 * @see ListableBeanFactory.getBeansWithAnnotation
+	 */
+	fun <T : Annotation> ListableBeanFactory.getBeansWithAnnotation(type: KClass<T>) =
+			getBeansWithAnnotation(type.java)
+
+	/**
+	 * @see ListableBeanFactoryExtension.findAnnotationOnBean
+	 */
+	fun <T : Annotation> ListableBeanFactory.findAnnotationOnBean(beanName:String, type: KClass<T>) =
+			findAnnotationOnBean(beanName, type.java)
+
+}

spring-context/src/main/kotlin/org/springframework/context/support/GenericApplicationContextExtension.kt

@@ -0,0 +1,47 @@
+package org.springframework.context.support
+
+import org.springframework.beans.factory.config.BeanDefinitionCustomizer
+import java.util.function.Supplier
+import kotlin.reflect.KClass
+
+/**
+ * Extension for [GenericApplicationContext] providing [KClass] based API and
+ * avoiding specifying a class parameter for the [Supplier] based variant thanks to
+ * Kotlin reified type parameters.
+ *
+ * @since 5.0
+ */
+object GenericApplicationContextExtension {
+
+	/**
+	 * @see GenericApplicationContext.registerBean(Class<T>, BeanDefinitionCustomizer...)
+	 */
+	fun <T : Any> GenericApplicationContext.registerBean(beanClass: KClass<T>,
+			vararg customizers: BeanDefinitionCustomizer) {
+					registerBean(beanClass.java, *customizers)
+	}
+
+	/**
+	 * @see GenericApplicationContext.registerBean(String, Class<T>, BeanDefinitionCustomizer...)
+	 */
+	fun <T : Any> GenericApplicationContext.registerBean(beanName: String, beanClass: KClass<T>,
+			vararg customizers: BeanDefinitionCustomizer) {
+					registerBean(beanName, beanClass.java, *customizers)
+	}
+
+	/**
+	 * @see GenericApplicationContext.registerBean(Class<T>, Supplier<T>, BeanDefinitionCustomizer...)
+	 */
+	inline fun <reified T : Any> GenericApplicationContext.registerBean(supplier: Supplier<T>,
+			vararg customizers: BeanDefinitionCustomizer) {
+					registerBean(T::class.java, supplier, *customizers)
+	}
+
+	/**
+	 * @see GenericApplicationContext.registerBean(String, Class<T>, Supplier<T>, BeanDefinitionCustomizer...)
+	 */
+	inline fun <reified T : Any> GenericApplicationContext.registerBean(name: String,
+			supplier: Supplier<T>, vararg customizers: BeanDefinitionCustomizer) {
+					registerBean(name, T::class.java, supplier, *customizers)
+	}
+}

spring-context/src/test/kotlin/org/springframework/context/support/GenericApplicationContextExtensionTests.kt

@@ -0,0 +1,45 @@
+package org.springframework.context.support
+
+import org.junit.Assert.assertNotNull
+import org.junit.Test
+import org.springframework.context.support.GenericApplicationContextExtension.registerBean
+import org.springframework.beans.factory.BeanFactoryExtension.getBean
+import java.util.function.Supplier
+
+class GenericApplicationContextExtensionTests {
+
+	@Test
+	fun registerBeanWithClass() {
+		val context = GenericApplicationContext()
+		context.registerBean(BeanA::class)
+		context.refresh()
+		assertNotNull(context.getBean(BeanA::class))
+	}
+
+	@Test
+	fun registerBeanWithNameAndClass() {
+		val context = GenericApplicationContext()
+		context.registerBean("a", BeanA::class)
+		context.refresh()
+		assertNotNull(context.getBean("a"))
+	}
+
+	@Test
+	fun registerBeanWithSupplier() {
+		val context = GenericApplicationContext()
+		context.registerBean(Supplier { BeanA() })
+		context.refresh()
+		assertNotNull(context.getBean(BeanA::class))
+	}
+
+	@Test
+	fun registerBeanWithNameAndSupplier() {
+		val context = GenericApplicationContext()
+		context.registerBean("a",  Supplier { BeanA() })
+		context.refresh()
+		assertNotNull(context.getBean("a"))
+	}
+
+	internal class BeanA
+
+}