Java tutorial
/* * Copyright 2002-2019 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.annotation; import java.io.IOException; import java.util.HashSet; import java.util.Map; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.aop.framework.AopInfrastructureBean; import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition; import org.springframework.beans.factory.config.BeanDefinition; import org.springframework.beans.factory.config.BeanFactoryPostProcessor; import org.springframework.beans.factory.config.BeanPostProcessor; import org.springframework.beans.factory.support.AbstractBeanDefinition; import org.springframework.context.event.EventListenerFactory; import org.springframework.core.Conventions; import org.springframework.core.Ordered; import org.springframework.core.annotation.AnnotationUtils; import org.springframework.core.annotation.Order; import org.springframework.core.type.AnnotationMetadata; import org.springframework.core.type.classreading.MetadataReader; import org.springframework.core.type.classreading.MetadataReaderFactory; import org.springframework.lang.Nullable; import org.springframework.stereotype.Component; /** * Utilities for identifying {@link Configuration} classes. * * @author Chris Beams * @author Juergen Hoeller * @since 3.1 */ abstract class ConfigurationClassUtils { public static final String CONFIGURATION_CLASS_FULL = "full"; public static final String CONFIGURATION_CLASS_LITE = "lite"; public static final String CONFIGURATION_CLASS_ATTRIBUTE = Conventions .getQualifiedAttributeName(ConfigurationClassPostProcessor.class, "configurationClass"); private static final String ORDER_ATTRIBUTE = Conventions .getQualifiedAttributeName(ConfigurationClassPostProcessor.class, "order"); private static final Log logger = LogFactory.getLog(ConfigurationClassUtils.class); private static final Set<String> candidateIndicators = new HashSet<>(8); static { candidateIndicators.add(Component.class.getName()); candidateIndicators.add(ComponentScan.class.getName()); candidateIndicators.add(Import.class.getName()); candidateIndicators.add(ImportResource.class.getName()); } /** * Check whether the given bean definition is a candidate for a configuration class * (or a nested component class declared within a configuration/component class, * to be auto-registered as well), and mark it accordingly. * @param beanDef the bean definition to check * @param metadataReaderFactory the current factory in use by the caller * @return whether the candidate qualifies as (any kind of) configuration class */ public static boolean checkConfigurationClassCandidate(BeanDefinition beanDef, MetadataReaderFactory metadataReaderFactory) { String className = beanDef.getBeanClassName(); if (className == null || beanDef.getFactoryMethodName() != null) { return false; } AnnotationMetadata metadata; if (beanDef instanceof AnnotatedBeanDefinition && className.equals(((AnnotatedBeanDefinition) beanDef).getMetadata().getClassName())) { // Can reuse the pre-parsed metadata from the given BeanDefinition... metadata = ((AnnotatedBeanDefinition) beanDef).getMetadata(); } else if (beanDef instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) beanDef).hasBeanClass()) { // Check already loaded Class if present... // since we possibly can't even load the class file for this Class. Class<?> beanClass = ((AbstractBeanDefinition) beanDef).getBeanClass(); if (BeanFactoryPostProcessor.class.isAssignableFrom(beanClass) || BeanPostProcessor.class.isAssignableFrom(beanClass) || AopInfrastructureBean.class.isAssignableFrom(beanClass) || EventListenerFactory.class.isAssignableFrom(beanClass)) { return false; } metadata = AnnotationMetadata.introspect(beanClass); } else { try { MetadataReader metadataReader = metadataReaderFactory.getMetadataReader(className); metadata = metadataReader.getAnnotationMetadata(); } catch (IOException ex) { if (logger.isDebugEnabled()) { logger.debug( "Could not find class file for introspecting configuration annotations: " + className, ex); } return false; } } Map<String, Object> config = metadata.getAnnotationAttributes(Configuration.class.getName()); if (config != null && !Boolean.FALSE.equals(config.get("proxyBeanMethods"))) { beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_FULL); } else if (config != null || isConfigurationCandidate(metadata)) { beanDef.setAttribute(CONFIGURATION_CLASS_ATTRIBUTE, CONFIGURATION_CLASS_LITE); } else { return false; } // It's a full or lite configuration candidate... Let's determine the order value, if any. Integer order = getOrder(metadata); if (order != null) { beanDef.setAttribute(ORDER_ATTRIBUTE, order); } return true; } /** * Check the given metadata for a configuration class candidate * (or nested component class declared within a configuration/component class). * @param metadata the metadata of the annotated class * @return {@code true} if the given class is to be registered for * configuration class processing; {@code false} otherwise */ public static boolean isConfigurationCandidate(AnnotationMetadata metadata) { // Do not consider an interface or an annotation... if (metadata.isInterface()) { return false; } // Any of the typical annotations found? for (String indicator : candidateIndicators) { if (metadata.isAnnotated(indicator)) { return true; } } // Finally, let's look for @Bean methods... try { return metadata.hasAnnotatedMethods(Bean.class.getName()); } catch (Throwable ex) { if (logger.isDebugEnabled()) { logger.debug( "Failed to introspect @Bean methods on class [" + metadata.getClassName() + "]: " + ex); } return false; } } /** * Determine the order for the given configuration class metadata. * @param metadata the metadata of the annotated class * @return the {@code @Order} annotation value on the configuration class, * or {@code Ordered.LOWEST_PRECEDENCE} if none declared * @since 5.0 */ @Nullable public static Integer getOrder(AnnotationMetadata metadata) { Map<String, Object> orderAttributes = metadata.getAnnotationAttributes(Order.class.getName()); return (orderAttributes != null ? ((Integer) orderAttributes.get(AnnotationUtils.VALUE)) : null); } /** * Determine the order for the given configuration class bean definition, * as set by {@link #checkConfigurationClassCandidate}. * @param beanDef the bean definition to check * @return the {@link Order @Order} annotation value on the configuration class, * or {@link Ordered#LOWEST_PRECEDENCE} if none declared * @since 4.2 */ public static int getOrder(BeanDefinition beanDef) { Integer order = (Integer) beanDef.getAttribute(ORDER_ATTRIBUTE); return (order != null ? order : Ordered.LOWEST_PRECEDENCE); } }