Add support for target type to BeanRegistry

Closes gh-34560

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

@@ -24,6 +24,8 @@ import org.springframework.beans.BeanUtils;
 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;
 
@@ -149,6 +151,20 @@ public interface BeanRegistry {
 		 * @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);
 	}
 
 	/**

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

@@ -30,6 +30,7 @@ import org.springframework.beans.factory.ListableBeanFactory;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinitionCustomizer;
+import org.springframework.core.ParameterizedTypeReference;
 import org.springframework.core.ResolvableType;
 import org.springframework.util.MultiValueMap;
 
@@ -211,6 +212,18 @@ public class BeanRegistryAdapter implements BeanRegistry {
 					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;
+		}
 	}
 
 	static class SupplierContextAdapter implements SupplierContext {

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

@@ -122,6 +122,10 @@ 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)
 	}
@@ -184,6 +188,10 @@ 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)
 	}
@@ -250,6 +258,10 @@ open class BeanRegistrarDsl(private val init: BeanRegistrarDsl.() -> Unit): Bean
 			it.supplier {
 				SupplierContextDsl<T>(it).supplier()
 			}
+			val resolvableType = ResolvableType.forType(object: ParameterizedTypeReference<T>() {});
+			if (resolvableType.hasGenerics()) {
+				it.targetType(resolvableType)
+			}
 		}
 		registry.registerBean(name, T::class.java, customizer)
 	}
@@ -314,6 +326,10 @@ open class BeanRegistrarDsl(private val init: BeanRegistrarDsl.() -> Unit): Bean
 			it.supplier {
 				SupplierContextDsl<T>(it).supplier()
 			}
+			val resolvableType = ResolvableType.forType(object: ParameterizedTypeReference<T>() {});
+			if (resolvableType.hasGenerics()) {
+				it.targetType(resolvableType)
+			}
 		}
 		return registry.registerBean(T::class.java, customizer)
 	}

spring-beans/src/test/java/org/springframework/beans/factory/support/BeanRegistryAdapterTests.java

@@ -23,6 +23,8 @@ import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.BeanRegistrar;
 import org.springframework.beans.factory.BeanRegistry;
 import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.core.ResolvableType;
 import org.springframework.core.env.Environment;
 import org.springframework.core.env.StandardEnvironment;
 
@@ -203,6 +205,22 @@ public class BeanRegistryAdapterTests {
 		assertThat(supplier.get()).isNotNull().isInstanceOf(Foo.class);
 	}
 
+	@Test
+	void customTargetTypeFromResolvableType() {
+		BeanRegistryAdapter adapter = new BeanRegistryAdapter(this.beanFactory, this.beanFactory, TargetTypeBeanRegistrar.class);
+		new TargetTypeBeanRegistrar().register(adapter, env);
+		RootBeanDefinition beanDefinition = (RootBeanDefinition)this.beanFactory.getBeanDefinition("fooSupplierFromResolvableType");
+		assertThat(beanDefinition.getResolvableType().resolveGeneric(0)).isEqualTo(Foo.class);
+	}
+
+	@Test
+	void customTargetTypeFromTypeReference() {
+		BeanRegistryAdapter adapter = new BeanRegistryAdapter(this.beanFactory, this.beanFactory, TargetTypeBeanRegistrar.class);
+		new TargetTypeBeanRegistrar().register(adapter, env);
+		RootBeanDefinition beanDefinition = (RootBeanDefinition)this.beanFactory.getBeanDefinition("fooSupplierFromTypeReference");
+		assertThat(beanDefinition.getResolvableType().resolveGeneric(0)).isEqualTo(Foo.class);
+	}
+
 
 	private static class DefaultBeanRegistrar implements BeanRegistrar {
 
@@ -292,6 +310,18 @@ public class BeanRegistryAdapterTests {
 		}
 	}
 
+	private static class TargetTypeBeanRegistrar implements BeanRegistrar {
+
+		@Override
+		public void register(BeanRegistry registry, Environment env) {
+			registry.registerBean("fooSupplierFromResolvableType", Foo.class,
+					spec -> spec.targetType(ResolvableType.forClassWithGenerics(Supplier.class, Foo.class)));
+			ParameterizedTypeReference<Supplier<Foo>> type = new ParameterizedTypeReference<>() {};
+			registry.registerBean("fooSupplierFromTypeReference", Supplier.class,
+					spec -> spec.targetType(type));
+		}
+	}
+
 	private static class Foo {}
 
 }

spring-context/src/test/java/org/springframework/context/annotation/beanregistrar/BeanRegistrarConfigurationTests.java

@@ -21,12 +21,15 @@ import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.BeanRegistrar;
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.config.BeanDefinition;
+import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.testfixture.beans.factory.GenericBeanRegistrar;
 import org.springframework.context.testfixture.beans.factory.SampleBeanRegistrar.Bar;
 import org.springframework.context.testfixture.beans.factory.SampleBeanRegistrar.Baz;
 import org.springframework.context.testfixture.beans.factory.SampleBeanRegistrar.Foo;
 import org.springframework.context.testfixture.beans.factory.SampleBeanRegistrar.Init;
 import org.springframework.context.testfixture.context.annotation.registrar.BeanRegistrarConfiguration;
+import org.springframework.context.testfixture.context.annotation.registrar.GenericBeanRegistrarConfiguration;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatThrownBy;
@@ -69,4 +72,13 @@ public class BeanRegistrarConfigurationTests {
 		assertThat(context.getBean(Init.class).initialized).isTrue();
 	}
 
+	@Test
+	void beanRegistrarWithTargetType() {
+		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		context.register(GenericBeanRegistrarConfiguration.class);
+		context.refresh();
+		RootBeanDefinition beanDefinition = (RootBeanDefinition)context.getBeanDefinition("fooSupplier");
+		assertThat(beanDefinition.getResolvableType().resolveGeneric(0)).isEqualTo(GenericBeanRegistrar.Foo.class);
+	}
+
 }

spring-context/src/test/kotlin/org/springframework/context/annotation/BeanRegistrarDslConfigurationTests.kt

@@ -20,11 +20,13 @@ import org.assertj.core.api.Assertions.assertThat
 import org.assertj.core.api.Assertions.assertThatThrownBy
 import org.assertj.core.api.ThrowableAssert
 import org.junit.jupiter.api.Test
+import org.springframework.beans.factory.BeanRegistrarDsl
 import org.springframework.beans.factory.InitializingBean
 import org.springframework.beans.factory.NoSuchBeanDefinitionException
 import org.springframework.beans.factory.config.BeanDefinition
 import org.springframework.beans.factory.getBean
-import org.springframework.beans.factory.BeanRegistrarDsl
+import org.springframework.beans.factory.support.RootBeanDefinition
+import java.util.function.Supplier
 
 /**
  * Kotlin tests leveraging [BeanRegistrarDsl].
@@ -56,6 +58,13 @@ class BeanRegistrarDslConfigurationTests {
 		assertThat(context.getBean<Init>().initialized).isTrue()
 	}
 
+	@Test
+	fun genericBeanRegistrar() {
+		val context = AnnotationConfigApplicationContext(GenericBeanRegistrarKotlinConfiguration::class.java)
+		val beanDefinition = context.getBeanDefinition("fooSupplier") as RootBeanDefinition
+		assertThat(beanDefinition.resolvableType.resolveGeneric(0)).isEqualTo(Foo::class.java)
+	}
+
 	class Foo
 	data class Bar(val foo: Foo)
 	data class Baz(val message: String = "")
@@ -86,4 +95,18 @@ class BeanRegistrarDslConfigurationTests {
 		}
 		registerBean<Init>()
 	})
+
+	@Configuration
+	@Import(GenericBeanRegistrar::class)
+	internal class GenericBeanRegistrarKotlinConfiguration
+
+	private class GenericBeanRegistrar : BeanRegistrarDsl({
+		registerBean<Supplier<Foo>>(name = "fooSupplier") {
+			object: Supplier<Foo> {
+				override fun get(): Foo {
+					return Foo()
+				}
+			}
+		}
+	})
 }

spring-context/src/testFixtures/java/org/springframework/context/testfixture/beans/factory/GenericBeanRegistrar.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2002-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.context.testfixture.beans.factory;
+
+import java.util.function.Supplier;
+
+import org.springframework.beans.factory.BeanRegistrar;
+import org.springframework.beans.factory.BeanRegistry;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.core.env.Environment;
+
+public class GenericBeanRegistrar implements BeanRegistrar {
+
+	@Override
+	public void register(BeanRegistry registry, Environment env) {
+		ParameterizedTypeReference<Supplier<Foo>> type = new ParameterizedTypeReference<>() {};
+		registry.registerBean("fooSupplier", Supplier.class, spec -> spec.targetType(type)
+				.supplier(context-> (Supplier<Foo>) Foo::new));
+	}
+
+	public record Foo() {}
+}

spring-context/src/testFixtures/java/org/springframework/context/testfixture/context/annotation/registrar/GenericBeanRegistrarConfiguration.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2002-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.context.testfixture.context.annotation.registrar;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.Import;
+import org.springframework.context.testfixture.beans.factory.GenericBeanRegistrar;
+
+@Configuration
+@Import(GenericBeanRegistrar.class)
+public class GenericBeanRegistrarConfiguration {
+}