Add support for BeanRegistrar registration on GenericApplicationContext

Closes gh-34574

Author: jhoeller

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

@@ -60,9 +60,10 @@
 public interface BeanRegistrar {
 
 	/**
-	 * Register beans in a programmatic way.
-	 * @param registry the bean registry
+	 * Register beans on the given {@link BeanRegistry} in a programmatic way.
+	 * @param registry the bean registry to operate on
 	 * @param env the environment that can be used to get the active profile or some properties
 	 */
 	void register(BeanRegistry registry, Environment env);
+
 }

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

@@ -56,6 +56,12 @@ public class BeanRegistryAdapter implements BeanRegistry {
 	private final @Nullable MultiValueMap<String, BeanDefinitionCustomizer> customizers;
 
 
+	public BeanRegistryAdapter(DefaultListableBeanFactory beanFactory, Environment environment,
+			Class<? extends BeanRegistrar> beanRegistrarClass) {
+
+		this(beanFactory, beanFactory, environment, beanRegistrarClass, null);
+	}
+
 	public BeanRegistryAdapter(BeanDefinitionRegistry beanRegistry, ListableBeanFactory beanFactory,
 			Environment environment, Class<? extends BeanRegistrar> beanRegistrarClass) {
 
@@ -73,6 +79,7 @@ public BeanRegistryAdapter(BeanDefinitionRegistry beanRegistry, ListableBeanFact
 		this.customizers = customizers;
 	}
 
+
 	@Override
 	public <T> String registerBean(Class<T> beanClass) {
 		String beanName = BeanDefinitionReaderUtils.uniqueBeanName(beanClass.getName(), this.beanRegistry);
@@ -154,7 +161,8 @@ public RootBeanDefinition cloneBeanDefinition() {
 		}
 	}
 
-	static class BeanSpecAdapter<T> implements Spec<T> {
+
+	private static class BeanSpecAdapter<T> implements Spec<T> {
 
 		private final RootBeanDefinition beanDefinition;
 
@@ -239,7 +247,8 @@ public Spec<T> targetType(ResolvableType targetType) {
 		}
 	}
 
-	static class SupplierContextAdapter implements SupplierContext {
+
+	private static class SupplierContextAdapter implements SupplierContext {
 
 		private final ListableBeanFactory beanFactory;
 

spring-context/src/main/java/org/springframework/context/annotation/AnnotationConfigRegistry.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.context.annotation;
 
+import org.springframework.beans.factory.BeanRegistrar;
+
 /**
  * Common interface for annotation config application contexts,
  * defining {@link #register} and {@link #scan} methods.
@@ -26,17 +28,33 @@
 public interface AnnotationConfigRegistry {
 
 	/**
-	 * Register one or more component classes to be processed.
+	 * Invoke the given registrars for registering their beans with this
+	 * application context.
+	 * <p>This can be used to register custom beans without inferring
+	 * annotation-based characteristics for primary/fallback/lazy-init,
+	 * rather specifying those programmatically if needed.
+	 * @param registrars one or more {@link BeanRegistrar} instances
+	 * @since 7.0
+	 * @see #register(Class[])
+	 */
+	void register(BeanRegistrar... registrars);
+
+	/**
+	 * Register one or more component classes to be processed, inferring
+	 * annotation-based characteristics for primary/fallback/lazy-init
+	 * just like for scanned component classes.
 	 * <p>Calls to {@code register} are idempotent; adding the same
 	 * component class more than once has no additional effect.
 	 * @param componentClasses one or more component classes,
 	 * for example, {@link Configuration @Configuration} classes
+	 * @see #scan(String...)
 	 */
 	void register(Class<?>... componentClasses);
 
 	/**
 	 * Perform a scan within the specified base packages.
 	 * @param basePackages the packages to scan for component classes
+	 * @see #register(Class[])
 	 */
 	void scan(String... basePackages);
 

spring-context/src/main/java/org/springframework/context/support/GenericApplicationContext.java

@@ -30,6 +30,7 @@
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanDefinitionStoreException;
+import org.springframework.beans.factory.BeanRegistrar;
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.config.AutowireCapableBeanFactory;
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -38,6 +39,7 @@
 import org.springframework.beans.factory.config.SmartInstantiationAwareBeanPostProcessor;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
+import org.springframework.beans.factory.support.BeanRegistryAdapter;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.MergedBeanDefinitionPostProcessor;
 import org.springframework.beans.factory.support.RootBeanDefinition;
@@ -594,6 +596,21 @@ public <T> void registerBean(@Nullable String beanName, Class<T> beanClass,
 		registerBeanDefinition(nameToUse, beanDefinition);
 	}
 
+	/**
+	 * Invoke the given registrars for registering their beans with this
+	 * application context.
+	 * <p>This can be used to apply encapsulated pieces of programmatic
+	 * bean registration to this application context without relying on
+	 * individual calls to its context-level {@code registerBean} methods.
+	 * @param registrars one or more {@link BeanRegistrar} instances
+	 * @since 7.0
+	 */
+	public void register(BeanRegistrar... registrars) {
+		for (BeanRegistrar registrar : registrars) {
+			new BeanRegistryAdapter(this.beanFactory, getEnvironment(), registrar.getClass()).register(registrar);
+		}
+	}
+
 
 	/**
 	 * {@link RootBeanDefinition} subclass for {@code #registerBean} based

spring-web/src/main/java/org/springframework/web/context/support/AnnotationConfigWebApplicationContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * 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.
@@ -22,7 +22,9 @@
 
 import org.jspecify.annotations.Nullable;
 
+import org.springframework.beans.factory.BeanRegistrar;
 import org.springframework.beans.factory.support.BeanNameGenerator;
+import org.springframework.beans.factory.support.BeanRegistryAdapter;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.context.annotation.AnnotatedBeanDefinitionReader;
 import org.springframework.context.annotation.AnnotationConfigRegistry;
@@ -104,6 +106,8 @@ public class AnnotationConfigWebApplicationContext extends AbstractRefreshableWe
 
 	private @Nullable ScopeMetadataResolver scopeMetadataResolver;
 
+	private final Set<BeanRegistrar> beanRegistrars = new LinkedHashSet<>();
+
 	private final Set<Class<?>> componentClasses = new LinkedHashSet<>();
 
 	private final Set<String> basePackages = new LinkedHashSet<>();
@@ -148,6 +152,20 @@ public void setScopeMetadataResolver(@Nullable ScopeMetadataResolver scopeMetada
 	}
 
 
+	/**
+	 * Invoke the given registrars for registering their beans with this
+	 * application context.
+	 * <p>Note that {@link #refresh()} must be called in order for the context
+	 * to fully process the new classes.
+	 * @param registrars one or more {@link BeanRegistrar} instances
+	 * @since 7.0
+	 */
+	@Override
+	public void register(BeanRegistrar... registrars) {
+		Assert.notEmpty(registrars, "At least one BeanRegistrar must be specified");
+		Collections.addAll(this.beanRegistrars, registrars);
+	}
+
 	/**
 	 * Register one or more component classes to be processed.
 	 * <p>Note that {@link #refresh()} must be called in order for the context
@@ -222,6 +240,16 @@ protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) {
 			scanner.setScopeMetadataResolver(scopeMetadataResolver);
 		}
 
+		if (!this.beanRegistrars.isEmpty()) {
+			if (logger.isDebugEnabled()) {
+				logger.debug("Applying bean registrars: [" +
+						StringUtils.collectionToCommaDelimitedString(this.beanRegistrars) + "]");
+			}
+			for (BeanRegistrar registrar : this.beanRegistrars) {
+				new BeanRegistryAdapter(beanFactory, getEnvironment(), registrar.getClass()).register(registrar);
+			}
+		}
+
 		if (!this.componentClasses.isEmpty()) {
 			if (logger.isDebugEnabled()) {
 				logger.debug("Registering component classes: [" +