Polish OnBeanCondition

Polish `OnBeanCondition` and make it easier to remove `BeanTypeRegistry`
in the future.

See gh-17594

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

@@ -81,7 +81,7 @@ abstract class FilteringSpringBootCondition extends SpringBootCondition
 		this.beanClassLoader = classLoader;
 	}
 
-	protected List<String> filter(Collection<String> classNames, ClassNameFilter classNameFilter,
+	protected final List<String> filter(Collection<String> classNames, ClassNameFilter classNameFilter,
 			ClassLoader classLoader) {
 		if (CollectionUtils.isEmpty(classNames)) {
 			return Collections.emptyList();
@@ -95,6 +95,22 @@ abstract class FilteringSpringBootCondition extends SpringBootCondition
 		return matches;
 	}
 
+	/**
+	 * Slightly faster variant of {@link ClassUtils#forName(String, ClassLoader)} that
+	 * doesn't deal with primitives, arrays or innter types.
+	 * @param className the class name to resolve
+	 * @param classLoader the class loader to use
+	 * @return a resolved class
+	 * @throws ClassNotFoundException if the class cannot be found
+	 */
+	protected static Class<?> resolve(String className, ClassLoader classLoader) throws ClassNotFoundException {
+		if (classLoader != null) {
+			return classLoader.loadClass(className);
+		}
+		return Class.forName(className);
+
+	}
+
 	protected enum ClassNameFilter {
 
 		PRESENT {
@@ -122,7 +138,7 @@ abstract class FilteringSpringBootCondition extends SpringBootCondition
 				classLoader = ClassUtils.getDefaultClassLoader();
 			}
 			try {
-				forName(className, classLoader);
+				resolve(className, classLoader);
 				return true;
 			}
 			catch (Throwable ex) {
@@ -130,13 +146,6 @@ abstract class FilteringSpringBootCondition extends SpringBootCondition
 			}
 		}
 
-		private static Class<?> forName(String className, ClassLoader classLoader) throws ClassNotFoundException {
-			if (classLoader != null) {
-				return classLoader.loadClass(className);
-			}
-			return Class.forName(className);
-		}
-
 	}
 
 }

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

@@ -438,7 +438,7 @@ public class ConditionalOnMissingBeanTests {
 		public void registerBeanDefinitions(AnnotationMetadata meta, BeanDefinitionRegistry registry) {
 			BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(NonspecificFactoryBean.class);
 			builder.addConstructorArgValue("foo");
-			builder.getBeanDefinition().setAttribute(OnBeanCondition.FACTORY_BEAN_OBJECT_TYPE, ExampleBean.class);
+			builder.getBeanDefinition().setAttribute(BeanTypeRegistry.FACTORY_BEAN_OBJECT_TYPE, ExampleBean.class);
 			registry.registerBeanDefinition("exampleBeanFactoryBean", builder.getBeanDefinition());
 		}
 
@@ -456,7 +456,7 @@ public class ConditionalOnMissingBeanTests {
 		public void registerBeanDefinitions(AnnotationMetadata meta, BeanDefinitionRegistry registry) {
 			BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(NonspecificFactoryBean.class);
 			builder.addConstructorArgValue("foo");
-			builder.getBeanDefinition().setAttribute(OnBeanCondition.FACTORY_BEAN_OBJECT_TYPE,
+			builder.getBeanDefinition().setAttribute(BeanTypeRegistry.FACTORY_BEAN_OBJECT_TYPE,
 					ExampleBean.class.getName());
 			registry.registerBeanDefinition("exampleBeanFactoryBean", builder.getBeanDefinition());
 		}
@@ -513,7 +513,7 @@ public class ConditionalOnMissingBeanTests {
 
 		@Bean
 		@ConditionalOnMissingBean(value = ExampleBean.class,
-				ignoredType = "org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBeanTests.CustomExampleBean")
+				ignoredType = "org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBeanTests$CustomExampleBean")
 		ExampleBean exampleBean() {
 			return new ExampleBean("test");
 		}

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

@@ -171,7 +171,7 @@ class ConditionalOnSingleCandidateTests {
 	}
 
 	@Configuration(proxyBeanMethods = false)
-	@ConditionalOnSingleCandidate(value = String.class, type = "java.lang.String")
+	@ConditionalOnSingleCandidate(value = String.class, type = "java.lang.Integer")
 	static class OnBeanSingleCandidateTwoTypesConfiguration {
 
 	}