Add first class ParameterizedTypeReference support to BeanRegistrar

This commit replaces ParameterizedTypeReference and ResolvableType
target type customization with the lambda by directly exposing
ParameterizedTypeReference methods at top level, as generics
variants of the class-based existing ones.

Closes gh-35635

Author: sdeleuze

spring-beans/src/main/java/org/springframework/beans/factory/BeanRegistry.java

@@ -24,7 +24,6 @@
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
-import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.env.Environment;
@@ -55,43 +54,92 @@ public interface BeanRegistry {
 	void registerAlias(String name, String alias);
 
 	/**
-	 * Register a bean from the given bean class, which will be instantiated using the
+	 * Register a bean from the given class, which will be instantiated using the
 	 * related {@link BeanUtils#getResolvableConstructor resolvable constructor} if any.
+	 * <p>For registering a bean with a generic type, consider
+	 * {@link #registerBean(ParameterizedTypeReference)}.
 	 * @param beanClass the class of the bean
 	 * @return the generated bean name
+	 * @see #registerBean(Class)
 	 */
 	<T> String registerBean(Class<T> beanClass);
 
 	/**
-	 * Register a bean from the given bean class, customizing it with the customizer
+	 * Register a bean from the given generics-containing type, which will be
+	 * instantiated using the related
+	 * {@link BeanUtils#getResolvableConstructor resolvable constructor} if any.
+	 * @param beanType the generics-containing type of the bean
+	 * @return the generated bean name
+	 */
+	<T> String registerBean(ParameterizedTypeReference<T> beanType);
+
+	/**
+	 * Register a bean from the given class, customizing it with the customizer
 	 * callback. The bean will be instantiated using the supplier that can be configured
 	 * in the customizer callback, or will be tentatively instantiated with its
 	 * {@link BeanUtils#getResolvableConstructor resolvable constructor} otherwise.
+	 * <p>For registering a bean with a generic type, consider
+	 * {@link #registerBean(ParameterizedTypeReference, Consumer)}.
 	 * @param beanClass the class of the bean
-	 * @param customizer callback to customize other bean properties than the name
+	 * @param customizer the callback to customize other bean properties than the name
 	 * @return the generated bean name
 	 */
 	<T> String registerBean(Class<T> beanClass, Consumer<Spec<T>> customizer);
 
 	/**
-	 * Register a bean from the given bean class, which will be instantiated using the
+	 * Register a bean from the given generics-containing type, customizing it
+	 * with the customizer callback. The bean will be instantiated using the supplier
+	 * that can be configured in the customizer callback, or will be tentatively instantiated
+	 * with its {@link BeanUtils#getResolvableConstructor resolvable constructor} otherwise.
+	 * @param beanType the generics-containing type of the bean
+	 * @param customizer the callback to customize other bean properties than the name
+	 * @return the generated bean name
+	 */
+	<T> String registerBean(ParameterizedTypeReference<T> beanType, Consumer<Spec<T>> customizer);
+
+	/**
+	 * Register a bean from the given class, which will be instantiated using the
 	 * related {@link BeanUtils#getResolvableConstructor resolvable constructor} if any.
+	 * <p>For registering a bean with a generic type, consider
+	 * {@link #registerBean(String, ParameterizedTypeReference)}.
 	 * @param name the name of the bean
 	 * @param beanClass the class of the bean
 	 */
 	<T> void registerBean(String name, Class<T> beanClass);
 
 	/**
-	 * Register a bean from the given bean class, customizing it with the customizer
+	 * Register a bean from the given generics-containing type, which
+	 * will be instantiated using the related
+	 * {@link BeanUtils#getResolvableConstructor resolvable constructor} if any.
+	 * @param name the name of the bean
+	 * @param beanType the generics-containing type of the bean
+	 */
+	<T> void registerBean(String name, ParameterizedTypeReference<T> beanType);
+
+	/**
+	 * Register a bean from the given class, customizing it with the customizer
 	 * callback. The bean will be instantiated using the supplier that can be configured
 	 * in the customizer callback, or will be tentatively instantiated with its
 	 * {@link BeanUtils#getResolvableConstructor resolvable constructor} otherwise.
+	 * <p>For registering a bean with a generic type, consider
+	 * {@link #registerBean(String, ParameterizedTypeReference, Consumer)}.
 	 * @param name the name of the bean
 	 * @param beanClass the class of the bean
-	 * @param customizer callback to customize other bean properties than the name
+	 * @param customizer the callback to customize other bean properties than the name
 	 */
 	<T> void registerBean(String name, Class<T> beanClass, Consumer<Spec<T>> customizer);
 
+	/**
+	 * Register a bean from the given generics-containing type, customizing it
+	 * with the customizer callback. The bean will be instantiated using the supplier
+	 * that can be configured in the customizer callback, or will be tentatively instantiated
+	 * with its {@link BeanUtils#getResolvableConstructor resolvable constructor} otherwise.
+	 * @param name the name of the bean
+	 * @param beanType the generics-containing type of the bean
+	 * @param customizer the callback to customize other bean properties than the name
+	 */
+	<T> void registerBean(String name, ParameterizedTypeReference<T> beanType, Consumer<Spec<T>> customizer);
+
 
 	/**
 	 * Specification for customizing a bean.
@@ -164,20 +212,6 @@ interface Spec<T> {
 		 * @see AbstractBeanDefinition#setInstanceSupplier(Supplier)
 		 */
 		Spec<T> supplier(Function<SupplierContext, T> supplier);
-
-		/**
-		 * Set a generics-containing target type of this bean.
-		 * @see #targetType(ResolvableType)
-		 * @see RootBeanDefinition#setTargetType(ResolvableType)
-		 */
-		Spec<T> targetType(ParameterizedTypeReference<? extends T> type);
-
-		/**
-		 * Set a generics-containing target type of this bean.
-		 * @see #targetType(ParameterizedTypeReference)
-		 * @see RootBeanDefinition#setTargetType(ResolvableType)
-		 */
-		Spec<T> targetType(ResolvableType type);
 	}
 
 
@@ -188,32 +222,40 @@ interface Spec<T> {
 	interface SupplierContext {
 
 		/**
-		 * Return the bean instance that uniquely matches the given object type, if any.
-		 * @param requiredType type the bean must match; can be an interface or superclass
-		 * @return an instance of the single bean matching the required type
+		 * Return the bean instance that uniquely matches the given type, if any.
+		 * @param beanClass the type the bean must match; can be an interface or superclass
+		 * @return an instance of the single bean matching the bean type
+		 * @see BeanFactory#getBean(String)
+		 */
+		<T> T bean(Class<T> beanClass) throws BeansException;
+
+		/**
+		 * Return the bean instance that uniquely matches the given generics-containing type, if any.
+		 * @param beanType the generics-containing type the bean must match; can be an interface or superclass
+		 * @return an instance of the single bean matching the bean type
 		 * @see BeanFactory#getBean(String)
 		 */
-		<T> T bean(Class<T> requiredType) throws BeansException;
+		<T> T bean(ParameterizedTypeReference<T> beanType) throws BeansException;
 
 		/**
 		 * Return an instance, which may be shared or independent, of the
 		 * specified bean.
 		 * @param name the name of the bean to retrieve
-		 * @param requiredType type the bean must match; can be an interface or superclass
+		 * @param beanClass the type the bean must match; can be an interface or superclass
 		 * @return an instance of the bean.
 		 * @see BeanFactory#getBean(String, Class)
 		 */
-		<T> T bean(String name, Class<T> requiredType) throws BeansException;
+		<T> T bean(String name, Class<T> beanClass) throws BeansException;
 
 		/**
 		 * Return a provider for the specified bean, allowing for lazy on-demand retrieval
 		 * of instances, including availability and uniqueness options.
-		 * <p>For matching a generic type, consider {@link #beanProvider(ResolvableType)}.
-		 * @param requiredType type the bean must match; can be an interface or superclass
+		 * <p>For matching a generic type, consider {@link #beanProvider(ParameterizedTypeReference)}.
+		 * @param beanClass the type the bean must match; can be an interface or superclass
 		 * @return a corresponding provider handle
 		 * @see BeanFactory#getBeanProvider(Class)
 		 */
-		<T> ObjectProvider<T> beanProvider(Class<T> requiredType);
+		<T> ObjectProvider<T> beanProvider(Class<T> beanClass);
 
 		/**
 		 * Return a provider for the specified bean, allowing for lazy on-demand retrieval
@@ -229,11 +271,11 @@ interface SupplierContext {
 		 * Java compiler warning), consider calling {@link #beanProvider(Class)} with the
 		 * raw type as a second step if no full generic match is
 		 * {@link ObjectProvider#getIfAvailable() available} with this variant.
-		 * @param requiredType type the bean must match; can be a generic type declaration
+		 * @param beanType the generics-containing type the bean must match; can be an interface or superclass
 		 * @return a corresponding provider handle
 		 * @see BeanFactory#getBeanProvider(ResolvableType)
 		 */
-		<T> ObjectProvider<T> beanProvider(ResolvableType requiredType);
+		<T> ObjectProvider<T> beanProvider(ParameterizedTypeReference<T> beanType);
 	}
 
 }

spring-beans/src/main/java/org/springframework/beans/factory/support/BeanRegistryAdapter.java

@@ -17,6 +17,7 @@
 package org.springframework.beans.factory.support;
 
 import java.lang.reflect.Constructor;
+import java.util.Objects;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
@@ -92,13 +93,30 @@ public <T> String registerBean(Class<T> beanClass) {
 		return beanName;
 	}
 
+	@Override
+	public <T> String registerBean(ParameterizedTypeReference<T> beanType) {
+		ResolvableType resolvableType = ResolvableType.forType(beanType);
+		String beanName = BeanDefinitionReaderUtils.uniqueBeanName(Objects.requireNonNull(resolvableType.resolve()).getName(), this.beanRegistry);
+		registerBean(beanName, beanType);
+		return beanName;
+	}
+
 	@Override
 	public <T> String registerBean(Class<T> beanClass, Consumer<Spec<T>> customizer) {
 		String beanName = BeanDefinitionReaderUtils.uniqueBeanName(beanClass.getName(), this.beanRegistry);
 		registerBean(beanName, beanClass, customizer);
 		return beanName;
 	}
 
+	@Override
+	public <T> String registerBean(ParameterizedTypeReference<T> beanType, Consumer<Spec<T>> customizer) {
+		ResolvableType resolvableType = ResolvableType.forType(beanType);
+		Class<?> beanClass = Objects.requireNonNull(resolvableType.resolve());
+		String beanName = BeanDefinitionReaderUtils.uniqueBeanName(beanClass.getName(), this.beanRegistry);
+		registerBean(beanName, beanType, customizer);
+		return beanName;
+	}
+
 	@Override
 	public <T> void registerBean(String name, Class<T> beanClass) {
 		BeanRegistrarBeanDefinition beanDefinition = new BeanRegistrarBeanDefinition(beanClass, this.beanRegistrarClass);
@@ -111,9 +129,11 @@ public <T> void registerBean(String name, Class<T> beanClass) {
 	}
 
 	@Override
-	public <T> void registerBean(String name, Class<T> beanClass, Consumer<Spec<T>> spec) {
+	public <T> void registerBean(String name, ParameterizedTypeReference<T> beanType) {
+		ResolvableType resolvableType = ResolvableType.forType(beanType);
+		Class<?> beanClass = Objects.requireNonNull(resolvableType.resolve());
 		BeanRegistrarBeanDefinition beanDefinition = new BeanRegistrarBeanDefinition(beanClass, this.beanRegistrarClass);
-		spec.accept(new BeanSpecAdapter<>(beanDefinition, this.beanFactory));
+		beanDefinition.setTargetType(resolvableType);
 		if (this.customizers != null && this.customizers.containsKey(name)) {
 			for (BeanDefinitionCustomizer customizer : this.customizers.get(name)) {
 				customizer.customize(beanDefinition);
@@ -122,6 +142,33 @@ public <T> void registerBean(String name, Class<T> beanClass, Consumer<Spec<T>>
 		this.beanRegistry.registerBeanDefinition(name, beanDefinition);
 	}
 
+	@Override
+	public <T> void registerBean(String name, Class<T> beanClass, Consumer<Spec<T>> customizer) {
+		BeanRegistrarBeanDefinition beanDefinition = new BeanRegistrarBeanDefinition(beanClass, this.beanRegistrarClass);
+		customizer.accept(new BeanSpecAdapter<>(beanDefinition, this.beanFactory));
+		if (this.customizers != null && this.customizers.containsKey(name)) {
+			for (BeanDefinitionCustomizer registryCustomizer : this.customizers.get(name)) {
+				registryCustomizer.customize(beanDefinition);
+			}
+		}
+		this.beanRegistry.registerBeanDefinition(name, beanDefinition);
+	}
+
+	@Override
+	public <T> void registerBean(String name, ParameterizedTypeReference<T> beanType, Consumer<Spec<T>> customizer) {
+		ResolvableType resolvableType = ResolvableType.forType(beanType);
+		Class<?> beanClass = Objects.requireNonNull(resolvableType.resolve());
+		BeanRegistrarBeanDefinition beanDefinition = new BeanRegistrarBeanDefinition(beanClass, this.beanRegistrarClass);
+		beanDefinition.setTargetType(resolvableType);
+		customizer.accept(new BeanSpecAdapter<>(beanDefinition, this.beanFactory));
+		if (this.customizers != null && this.customizers.containsKey(name)) {
+			for (BeanDefinitionCustomizer registryCustomizer : this.customizers.get(name)) {
+				registryCustomizer.customize(beanDefinition);
+			}
+		}
+		this.beanRegistry.registerBeanDefinition(name, beanDefinition);
+	}
+
 	@Override
 	public void register(BeanRegistrar registrar) {
 		Assert.notNull(registrar, "'registrar' must not be null");
@@ -238,18 +285,6 @@ public Spec<T> supplier(Function<SupplierContext, T> supplier) {
 					supplier.apply(new SupplierContextAdapter(this.beanFactory)));
 			return this;
 		}
-
-		@Override
-		public Spec<T> targetType(ParameterizedTypeReference<? extends T> targetType) {
-			this.beanDefinition.setTargetType(ResolvableType.forType(targetType));
-			return this;
-		}
-
-		@Override
-		public Spec<T> targetType(ResolvableType targetType) {
-			this.beanDefinition.setTargetType(targetType);
-			return this;
-		}
 	}
 
 
@@ -262,23 +297,28 @@ public SupplierContextAdapter(ListableBeanFactory beanFactory) {
 		}
 
 		@Override
-		public <T> T bean(Class<T> requiredType) throws BeansException {
-			return this.beanFactory.getBean(requiredType);
+		public <T> T bean(Class<T> beanClass) throws BeansException {
+			return this.beanFactory.getBean(beanClass);
+		}
+
+		@Override
+		public <T> T bean(ParameterizedTypeReference<T> beanType) throws BeansException {
+			return this.beanFactory.getBeanProvider(beanType).getObject();
 		}
 
 		@Override
-		public <T> T bean(String name, Class<T> requiredType) throws BeansException {
-			return this.beanFactory.getBean(name, requiredType);
+		public <T> T bean(String name, Class<T> beanClass) throws BeansException {
+			return this.beanFactory.getBean(name, beanClass);
 		}
 
 		@Override
-		public <T> ObjectProvider<T> beanProvider(Class<T> requiredType) {
-			return this.beanFactory.getBeanProvider(requiredType);
+		public <T> ObjectProvider<T> beanProvider(Class<T> beanClass) {
+			return this.beanFactory.getBeanProvider(beanClass);
 		}
 
 		@Override
-		public <T> ObjectProvider<T> beanProvider(ResolvableType requiredType) {
-			return this.beanFactory.getBeanProvider(requiredType);
+		public <T> ObjectProvider<T> beanProvider(ParameterizedTypeReference<T> beanType) {
+			return this.beanFactory.getBeanProvider(beanType);
 		}
 	}
 

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

@@ -168,12 +168,8 @@ open class BeanRegistrarDsl(private val init: BeanRegistrarDsl.() -> Unit): Bean
 			if (prototype) {
 				it.prototype()
 			}
-			val resolvableType = ResolvableType.forType(object: ParameterizedTypeReference<T>() {});
-			if (resolvableType.hasGenerics()) {
-				it.targetType(resolvableType)
-			}
 		}
-		registry.registerBean(name, T::class.java, customizer)
+		registry.registerBean(name, object: ParameterizedTypeReference<T>() {}, customizer)
 	}
 
 	/**
@@ -234,12 +230,8 @@ open class BeanRegistrarDsl(private val init: BeanRegistrarDsl.() -> Unit): Bean
 			if (prototype) {
 				it.prototype()
 			}
-			val resolvableType = ResolvableType.forType(object: ParameterizedTypeReference<T>() {});
-			if (resolvableType.hasGenerics()) {
-				it.targetType(resolvableType)
-			}
 		}
-		return registry.registerBean(T::class.java, customizer)
+		return registry.registerBean(object: ParameterizedTypeReference<T>() {}, customizer)
 	}
 
 	/**
@@ -304,12 +296,8 @@ open class BeanRegistrarDsl(private val init: BeanRegistrarDsl.() -> Unit): Bean
 			it.supplier {
 				SupplierContextDsl<T>(it, env).supplier()
 			}
-			val resolvableType = ResolvableType.forType(object: ParameterizedTypeReference<T>() {});
-			if (resolvableType.hasGenerics()) {
-				it.targetType(resolvableType)
-			}
 		}
-		registry.registerBean(name, T::class.java, customizer)
+		registry.registerBean(name, object: ParameterizedTypeReference<T>() {}, customizer)
 	}
 
 	inline fun <reified T : Any> registerBean(autowirable: Boolean = true,
@@ -372,12 +360,8 @@ open class BeanRegistrarDsl(private val init: BeanRegistrarDsl.() -> Unit): Bean
 			it.supplier {
 				SupplierContextDsl<T>(it, env).supplier()
 			}
-			val resolvableType = ResolvableType.forType(object: ParameterizedTypeReference<T>() {});
-			if (resolvableType.hasGenerics()) {
-				it.targetType(resolvableType)
-			}
 		}
-		return registry.registerBean(T::class.java, customizer)
+		return registry.registerBean(object: ParameterizedTypeReference<T>() {}, customizer)
 	}
 
 	// Function with 0 parameter
@@ -1094,7 +1078,7 @@ open class BeanRegistrarDsl(private val init: BeanRegistrarDsl.() -> Unit): Bean
 		 * @return a corresponding provider handle
 		 */
 		inline fun <reified T : Any> beanProvider() : ObjectProvider<T> =
-			context.beanProvider(ResolvableType.forType((object : ParameterizedTypeReference<T>() {}).type))
+			context.beanProvider(object : ParameterizedTypeReference<T>() {})
 	}
 
 	override fun register(registry: BeanRegistry, env: Environment) {