Avoid eager initialization when finding beans by annotation

Closes gh-8269

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/BeanTypeRegistry.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.autoconfigure.condition;
 
+import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
 import java.util.Arrays;
 import java.util.HashMap;
@@ -40,6 +41,7 @@ import org.springframework.beans.factory.support.AbstractBeanDefinition;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.core.ResolvableType;
+import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.type.MethodMetadata;
 import org.springframework.core.type.StandardMethodMetadata;
 import org.springframework.util.Assert;
@@ -85,7 +87,7 @@ final class BeanTypeRegistry implements SmartInitializingSingleton {
 	 * @param beanFactory the source bean factory
 	 * @return the {@link BeanTypeRegistry} for the given bean factory
 	 */
-	public static BeanTypeRegistry create(ListableBeanFactory beanFactory) {
+	static BeanTypeRegistry get(ListableBeanFactory beanFactory) {
 		Assert.isInstanceOf(DefaultListableBeanFactory.class, beanFactory);
 		DefaultListableBeanFactory listableBeanFactory = (DefaultListableBeanFactory) beanFactory;
 		Assert.isTrue(listableBeanFactory.isAllowEagerClassLoading(),
@@ -101,23 +103,15 @@ final class BeanTypeRegistry implements SmartInitializingSingleton {
 
 	/**
 	 * Return the names of beans matching the given type (including subclasses), judging
-	 * from either bean definitions or the value of {@code getObjectType} in the case of
+	 * from either bean definitions or the value of {@link FactoryBean#getObjectType()} in
-	 * FactoryBeans. Will include singletons but not cause early bean initialization.
+	 * the case of {@link FactoryBean FactoryBeans}. Will include singletons but will not
+	 * cause early bean initialization.
 	 * @param type the class or interface to match (must not be {@code null})
 	 * @return the names of beans (or objects created by FactoryBeans) matching the given
 	 * object type (including subclasses), or an empty set if none
 	 */
 	Set<String> getNamesForType(Class<?> type) {
-		if (this.lastBeanDefinitionCount != this.beanFactory.getBeanDefinitionCount()) {
+		updateTypesIfNecessary();
-			Iterator<String> names = this.beanFactory.getBeanNamesIterator();
-			while (names.hasNext()) {
-				String name = names.next();
-				if (!this.beanTypes.containsKey(name)) {
-					addBeanType(name);
-				}
-			}
-			this.lastBeanDefinitionCount = this.beanFactory.getBeanDefinitionCount();
-		}
 		Set<String> matches = new LinkedHashSet<String>();
 		for (Map.Entry<String, Class<?>> entry : this.beanTypes.entrySet()) {
 			if (entry.getValue() != null && type.isAssignableFrom(entry.getValue())) {
@@ -127,6 +121,27 @@ final class BeanTypeRegistry implements SmartInitializingSingleton {
 		return matches;
 	}
 
+	/**
+	 * Returns the names of beans annotated with the given {@code annotation}, judging
+	 * from either bean definitions or the value of {@link FactoryBean#getObjectType()} in
+	 * the case of {@link FactoryBean FactoryBeans}. Will include singletons but will not
+	 * cause early bean initialization.
+	 * @param annotation the annotation to match (must not be {@code null})
+	 * @return the names of beans (or objects created by FactoryBeans) annoated with the
+	 * given annotation, or an empty set if none
+	 */
+	Set<String> getNamesForAnnotation(Class<? extends Annotation> annotation) {
+		updateTypesIfNecessary();
+		Set<String> matches = new LinkedHashSet<String>();
+		for (Map.Entry<String, Class<?>> entry : this.beanTypes.entrySet()) {
+			if (entry.getValue() != null && AnnotationUtils
+					.findAnnotation(entry.getValue(), annotation) != null) {
+				matches.add(entry.getKey());
+			}
+		}
+		return matches;
+	}
+
 	@Override
 	public void afterSingletonsInstantiated() {
 		// We're done at this point, free up some memory
@@ -183,6 +198,19 @@ final class BeanTypeRegistry implements SmartInitializingSingleton {
 				&& !this.beanFactory.containsSingleton(factoryBeanName));
 	}
 
+	private void updateTypesIfNecessary() {
+		if (this.lastBeanDefinitionCount != this.beanFactory.getBeanDefinitionCount()) {
+			Iterator<String> names = this.beanFactory.getBeanNamesIterator();
+			while (names.hasNext()) {
+				String name = names.next();
+				if (!this.beanTypes.containsKey(name)) {
+					addBeanType(name);
+				}
+			}
+			this.lastBeanDefinitionCount = this.beanFactory.getBeanDefinitionCount();
+		}
+	}
+
 	/**
 	 * Attempt to guess the type that a {@link FactoryBean} will return based on the
 	 * generics in its method signature.

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnBeanCondition.java

@@ -22,6 +22,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
@@ -59,8 +60,6 @@ import org.springframework.util.StringUtils;
 @Order(Ordered.LOWEST_PRECEDENCE)
 class OnBeanCondition extends SpringBootCondition implements ConfigurationCondition {
 
-	private static final String[] NO_BEANS = {};
-
 	/**
 	 * Bean definition attribute name for factory beans to signal their product type (if
 	 * known and it can't be deduced from the factory bean class).
@@ -184,7 +183,7 @@ class OnBeanCondition extends SpringBootCondition implements ConfigurationCondit
 
 	private void collectBeanNamesForType(Set<String> result,
 			ListableBeanFactory beanFactory, Class<?> type, boolean considerHierarchy) {
-		result.addAll(BeanTypeRegistry.create(beanFactory).getNamesForType(type));
+		result.addAll(BeanTypeRegistry.get(beanFactory).getNamesForType(type));
 		if (considerHierarchy && beanFactory instanceof HierarchicalBeanFactory) {
 			BeanFactory parent = ((HierarchicalBeanFactory) beanFactory)
 					.getParentBeanFactory();
@@ -198,35 +197,33 @@ class OnBeanCondition extends SpringBootCondition implements ConfigurationCondit
 	private String[] getBeanNamesForAnnotation(
 			ConfigurableListableBeanFactory beanFactory, String type,
 			ClassLoader classLoader, boolean considerHierarchy) throws LinkageError {
-		String[] result = NO_BEANS;
+		Set<String> names = new HashSet<String>();
 		try {
 			@SuppressWarnings("unchecked")
-			Class<? extends Annotation> typeClass = (Class<? extends Annotation>) ClassUtils
+			Class<? extends Annotation> annotationType = (Class<? extends Annotation>) ClassUtils
 					.forName(type, classLoader);
-			result = beanFactory.getBeanNamesForAnnotation(typeClass);
+			collectBeanNamesForAnnotation(names, beanFactory, annotationType,
+					considerHierarchy);
+		}
+		catch (ClassNotFoundException e) {
+			// Continue
+		}
+		return StringUtils.toStringArray(names);
+	}
+
+	private void collectBeanNamesForAnnotation(Set<String> names,
+			ListableBeanFactory beanFactory, Class<? extends Annotation> annotationType,
+			boolean considerHierarchy) {
+		names.addAll(
+				BeanTypeRegistry.get(beanFactory).getNamesForAnnotation(annotationType));
 		if (considerHierarchy) {
-				if (beanFactory
+			BeanFactory parent = ((HierarchicalBeanFactory) beanFactory)
-						.getParentBeanFactory() instanceof ConfigurableListableBeanFactory) {
+					.getParentBeanFactory();
-					String[] parentResult = getBeanNamesForAnnotation(
+			if (parent instanceof ListableBeanFactory) {
-							(ConfigurableListableBeanFactory) beanFactory
+				collectBeanNamesForAnnotation(names, (ListableBeanFactory) parent,
-									.getParentBeanFactory(),
+						annotationType, considerHierarchy);
-							type, classLoader, true);
-					List<String> resultList = new ArrayList<String>();
-					resultList.addAll(Arrays.asList(result));
-					for (String beanName : parentResult) {
-						if (!resultList.contains(beanName)
-								&& !beanFactory.containsLocalBean(beanName)) {
-							resultList.add(beanName);
 			}
 		}
-					result = StringUtils.toStringArray(resultList);
-				}
-			}
-			return result;
-		}
-		catch (ClassNotFoundException ex) {
-			return NO_BEANS;
-		}
 	}
 
 	private boolean hasSingleAutowireCandidate(

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnBeanTests.java

@@ -16,10 +16,16 @@
 
 package org.springframework.boot.autoconfigure.condition;
 
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
 import java.util.Date;
 
 import org.junit.Test;
 
+import org.springframework.beans.factory.FactoryBean;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.boot.test.util.EnvironmentTestUtils;
@@ -124,6 +130,15 @@ public class ConditionalOnBeanTests {
 		this.context.refresh();
 	}
 
+	@Test
+	public void beanProducedByFactoryBeanIsConsideredWhenMatchingOnAnnotation() {
+		this.context.register(FactoryBeanConfiguration.class,
+				OnAnnotationWithFactoryBeanConfiguration.class);
+		this.context.refresh();
+		assertThat(this.context.containsBean("bar")).isTrue();
+		assertThat(this.context.getBeansOfType(ExampleBean.class)).hasSize(1);
+	}
+
 	@Configuration
 	@ConditionalOnBean(name = "foo")
 	protected static class OnBeanNameConfiguration {
@@ -220,6 +235,27 @@ public class ConditionalOnBeanTests {
 
 	}
 
+	@Configuration
+	static class FactoryBeanConfiguration {
+
+		@Bean
+		public ExampleFactoryBean exampleBeanFactoryBean() {
+			return new ExampleFactoryBean();
+		}
+
+	}
+
+	@Configuration
+	@ConditionalOnBean(annotation = TestAnnotation.class)
+	static class OnAnnotationWithFactoryBeanConfiguration {
+
+		@Bean
+		public String bar() {
+			return "bar";
+		}
+
+	}
+
 	protected static class WithPropertyPlaceholderClassNameRegistrar
 			implements ImportBeanDefinitionRegistrar {
 
@@ -233,4 +269,46 @@ public class ConditionalOnBeanTests {
 
 	}
 
+	public static class ExampleFactoryBean implements FactoryBean<ExampleBean> {
+
+		@Override
+		public ExampleBean getObject() throws Exception {
+			return new ExampleBean("fromFactory");
+		}
+
+		@Override
+		public Class<?> getObjectType() {
+			return ExampleBean.class;
+		}
+
+		@Override
+		public boolean isSingleton() {
+			return false;
+		}
+
+	}
+
+	@TestAnnotation
+	public static class ExampleBean {
+
+		private String value;
+
+		public ExampleBean(String value) {
+			this.value = value;
+		}
+
+		@Override
+		public String toString() {
+			return this.value;
+		}
+
+	}
+
+	@Target(ElementType.TYPE)
+	@Retention(RetentionPolicy.RUNTIME)
+	@Documented
+	public @interface TestAnnotation {
+
+	}
+
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/condition/ConditionalOnMissingBeanTests.java

@@ -16,6 +16,11 @@
 
 package org.springframework.boot.autoconfigure.condition;
 
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
 import java.util.Date;
 
 import org.junit.Test;
@@ -285,6 +290,15 @@ public class ConditionalOnMissingBeanTests {
 		assertThat(child.getBeansOfType(ExampleBean.class)).hasSize(2);
 	}
 
+	@Test
+	public void beanProducedByFactoryBeanIsConsideredWhenMatchingOnAnnotation() {
+		this.context.register(ConcreteFactoryBeanConfiguration.class,
+				OnAnnotationWithFactoryBeanConfiguration.class);
+		this.context.refresh();
+		assertThat(this.context.containsBean("bar")).isFalse();
+		assertThat(this.context.getBeansOfType(ExampleBean.class)).hasSize(1);
+	}
+
 	@Configuration
 	protected static class OnBeanInParentsConfiguration {
 
@@ -500,6 +514,17 @@ public class ConditionalOnMissingBeanTests {
 
 	}
 
+	@Configuration
+	@ConditionalOnMissingBean(annotation = TestAnnotation.class)
+	protected static class OnAnnotationWithFactoryBeanConfiguration {
+
+		@Bean
+		public String bar() {
+			return "bar";
+		}
+
+	}
+
 	@Configuration
 	@EnableScheduling
 	protected static class FooConfiguration {
@@ -554,6 +579,7 @@ public class ConditionalOnMissingBeanTests {
 
 	}
 
+	@TestAnnotation
 	public static class ExampleBean {
 
 		private String value;
@@ -623,4 +649,11 @@ public class ConditionalOnMissingBeanTests {
 
 	}
 
+	@Target(ElementType.TYPE)
+	@Retention(RetentionPolicy.RUNTIME)
+	@Documented
+	public @interface TestAnnotation {
+
+	}
+
 }