Support ResolvableType in BeanDefinitionBuilder

Closes gh-27160

Author: snicoll

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

@@ -21,6 +21,7 @@
 import org.springframework.beans.factory.config.AutowiredPropertyMarker;
 import org.springframework.beans.factory.config.BeanDefinitionCustomizer;
 import org.springframework.beans.factory.config.RuntimeBeanReference;
+import org.springframework.core.ResolvableType;
 import org.springframework.lang.Nullable;
 import org.springframework.util.ObjectUtils;
 
@@ -102,7 +103,7 @@ public static BeanDefinitionBuilder rootBeanDefinition(String beanClassName, @Nu
 	 * @param beanClass the {@code Class} of the bean that the definition is being created for
 	 */
 	public static BeanDefinitionBuilder rootBeanDefinition(Class<?> beanClass) {
-		return rootBeanDefinition(beanClass, null);
+		return rootBeanDefinition(beanClass, (String) null);
 	}
 
 	/**
@@ -117,6 +118,30 @@ public static BeanDefinitionBuilder rootBeanDefinition(Class<?> beanClass, @Null
 		return builder;
 	}
 
+	/**
+	 * Create a new {@code BeanDefinitionBuilder} used to construct a {@link RootBeanDefinition}.
+	 * @param beanType the {@link ResolvableType type} of the bean that the definition is being created for
+	 * @param instanceSupplier a callback for creating an instance of the bean
+	 * @since 5.3.9
+	 */
+	public static <T> BeanDefinitionBuilder rootBeanDefinition(ResolvableType beanType, Supplier<T> instanceSupplier) {
+		RootBeanDefinition beanDefinition = new RootBeanDefinition();
+		beanDefinition.setTargetType(beanType);
+		beanDefinition.setInstanceSupplier(instanceSupplier);
+		return new BeanDefinitionBuilder(beanDefinition);
+	}
+
+	/**
+	 * Create a new {@code BeanDefinitionBuilder} used to construct a {@link RootBeanDefinition}.
+	 * @param beanClass the {@code Class} of the bean that the definition is being created for
+	 * @param instanceSupplier a callback for creating an instance of the bean
+	 * @since 5.3.9
+	 * @see #rootBeanDefinition(ResolvableType, Supplier)
+	 */
+	public static <T> BeanDefinitionBuilder rootBeanDefinition(Class<T> beanClass, Supplier<T> instanceSupplier) {
+		return rootBeanDefinition(ResolvableType.forClass(beanClass), instanceSupplier);
+	}
+
 	/**
 	 * Create a new {@code BeanDefinitionBuilder} used to construct a {@link ChildBeanDefinition}.
 	 * @param parentName the name of the parent bean

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

@@ -17,11 +17,13 @@
 package org.springframework.beans.factory.support;
 
 import java.util.Arrays;
+import java.util.function.Function;
 
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.testfixture.beans.TestBean;
+import org.springframework.core.ResolvableType;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -75,6 +77,26 @@ void builderWithBeanClassNameAndFactoryMethod() {
 		assertThat(rbd.getFactoryMethodName()).isEqualTo("create");
 	}
 
+	@Test
+	void builderWithResolvableTypeAndInstanceSupplier() {
+		ResolvableType type = ResolvableType.forClassWithGenerics(Function.class, Integer.class, String.class);
+		Function<Integer, String> function = i -> "value " + i;
+		RootBeanDefinition rbd = (RootBeanDefinition) BeanDefinitionBuilder
+				.rootBeanDefinition(type, () -> function).getBeanDefinition();
+		assertThat(rbd.getResolvableType()).isEqualTo(type);
+		assertThat(rbd.getInstanceSupplier()).isNotNull();
+		assertThat(rbd.getInstanceSupplier().get()).isInstanceOf(Function.class);
+	}
+
+	@Test
+	void builderWithBeanClassAndInstanceSupplier() {
+		RootBeanDefinition rbd = (RootBeanDefinition) BeanDefinitionBuilder
+				.rootBeanDefinition(String.class, () -> "test").getBeanDefinition();
+		assertThat(rbd.getResolvableType().resolve()).isEqualTo(String.class);
+		assertThat(rbd.getInstanceSupplier()).isNotNull();
+		assertThat(rbd.getInstanceSupplier().get()).isEqualTo("test");
+	}
+
 	@Test
 	void builderWithAutowireMode() {
 		assertThat(BeanDefinitionBuilder.rootBeanDefinition(TestBean.class)