Introduce new Spring ApplicationContext implementation and extension that is Refreshable and can be configured with Annotations.
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John Blum
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/*
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* Copyright 2020 the original author or authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* https://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
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* or implied. See the License for the specific language governing
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* permissions and limitations under the License.
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*/
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package org.springframework.geode.context.annotation;
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import java.lang.annotation.Annotation;
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import java.util.Arrays;
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import java.util.LinkedHashSet;
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import java.util.Objects;
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import java.util.Optional;
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import java.util.Set;
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import org.springframework.beans.BeansException;
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import org.springframework.beans.factory.config.BeanDefinition;
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import org.springframework.beans.factory.support.BeanDefinitionRegistry;
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import org.springframework.beans.factory.support.BeanNameGenerator;
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import org.springframework.beans.factory.support.DefaultListableBeanFactory;
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import org.springframework.context.ApplicationContext;
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import org.springframework.context.annotation.AnnotatedBeanDefinitionReader;
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import org.springframework.context.annotation.AnnotationConfigRegistry;
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import org.springframework.context.annotation.AnnotationConfigUtils;
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import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
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import org.springframework.context.annotation.ScopeMetadataResolver;
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import org.springframework.context.support.AbstractRefreshableConfigApplicationContext;
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import org.springframework.data.gemfire.util.ArrayUtils;
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import org.springframework.lang.Nullable;
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import org.springframework.util.ClassUtils;
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import org.springframework.util.StringUtils;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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/**
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* A {@literal refreshable} {@link ApplicationContext} capable of loading {@link Class component classes} common
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* in {@link Annotation} based configuration as well as scanning {@link String configuration locations}.
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*
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* @author John Blum
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* @see org.springframework.beans.factory.config.BeanDefinition
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* @see org.springframework.beans.factory.support.BeanDefinitionRegistry
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* @see org.springframework.beans.factory.support.BeanNameGenerator
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* @see org.springframework.beans.factory.support.DefaultListableBeanFactory
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* @see org.springframework.context.ApplicationContext
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* @see org.springframework.context.annotation.AnnotatedBeanDefinitionReader
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* @see org.springframework.context.annotation.AnnotationConfigRegistry
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* @see org.springframework.context.annotation.ClassPathBeanDefinitionScanner
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* @see org.springframework.context.annotation.ScopeMetadataResolver
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* @see org.springframework.context.support.AbstractRefreshableConfigApplicationContext
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* @since 1.3.0
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*/
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@SuppressWarnings("unused")
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public class RefreshableAnnotationConfigApplicationContext extends AbstractRefreshableConfigApplicationContext
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implements AnnotationConfigRegistry {
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protected static final boolean USE_DEFAULT_FILTERS = true;
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@Nullable
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private BeanNameGenerator beanNameGenerator;
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private volatile DefaultListableBeanFactory beanFactory;
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private final Logger logger = LoggerFactory.getLogger(getClass());
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private final Set<String> basePackages = new LinkedHashSet<>();
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private final Set<Class<?>> componentClasses = new LinkedHashSet<>();
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@Nullable
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private ScopeMetadataResolver scopeMetadataResolver;
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/**
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* Constructs an new instance of the {@link RefreshableAnnotationConfigApplicationContext}
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* with default container state an no {@literal parent} {@link ApplicationContext}.
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*
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* @see #refreshBeanFactory()
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*/
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public RefreshableAnnotationConfigApplicationContext() {
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refreshBeanFactory(); // TODO: Not certain this is a good idea; see comment below on createBeanFactory() method!
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}
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/**
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* Constructs a new instance of the {@link RefreshableAnnotationConfigApplicationContext} initialized with
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* the {@literal parent} {@link ApplicationContext}.
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*
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* @param parent parent {@link ApplicationContext} to this context.
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* @see org.springframework.context.ApplicationContext
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* @see #refreshBeanFactory()
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*/
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public RefreshableAnnotationConfigApplicationContext(@Nullable ApplicationContext parent) {
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super(parent);
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refreshBeanFactory(); // TODO: Not certain this is a good idea; see comment below on createBeanFactory() method!
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}
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/**
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* Configures the {@link BeanNameGenerator} strategy used by this {@link ApplicationContext} to generate
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* {@link String bean names} for {@link BeanDefinition bean definitions}.
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*
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* @param beanNameGenerator {@link BeanNameGenerator} used to generate {@link String bean names}
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* for {@link BeanDefinition bean definitions}.
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* @see org.springframework.beans.factory.support.BeanNameGenerator
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*/
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public void setBeanNameGenerator(@Nullable BeanNameGenerator beanNameGenerator) {
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this.beanNameGenerator = beanNameGenerator;
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}
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/**
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* Returns the {@link Optional optionally} configured {@link BeanNameGenerator} strategy used by this
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* {@link ApplicationContext} to generate {@link String bean names} for {@link BeanDefinition bean definitions}.
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*
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* @return the {@link BeanNameGenerator} strategy used to generate {@link String bean names}
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* for {@link BeanDefinition bean definitions}.
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* @see org.springframework.beans.factory.support.BeanNameGenerator
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* @see java.util.Optional
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*/
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protected Optional<BeanNameGenerator> getBeanNameGenerator() {
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return Optional.ofNullable(this.beanNameGenerator);
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}
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/**
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* Returns the configured {@link Logger} used to log framework {@link String messages} to the application log.
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*
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* @return the configured {@link Logger}.
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* @see org.slf4j.Logger
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*/
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protected Logger getLogger() {
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return this.logger;
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}
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/**
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* Configures the {@link ScopeMetadataResolver} strategy used by this {@link ApplicationContext} to resolve
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* the {@literal scope} for {@link BeanDefinition bean definitions}.
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*
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* @param scopeMetadataResolver {@link ScopeMetadataResolver} used to resolve the {@literal scope}
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* of {@link BeanDefinition bean definitions}.
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* @see org.springframework.context.annotation.ScopeMetadataResolver
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*/
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public void setScopeMetadataResolver(@Nullable ScopeMetadataResolver scopeMetadataResolver) {
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this.scopeMetadataResolver = scopeMetadataResolver;
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}
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/**
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* Returns the {@link Optional optionally} configured {@link ScopeMetadataResolver} strategy used by
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* this {@link ApplicationContext} to resolve the {@literal scope} for {@link BeanDefinition bean definitions}.
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*
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* @return the configured {@link ScopeMetadataResolver} used to resolve the {@literal scope}
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* for {@link BeanDefinition bean definitions}.
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* @see org.springframework.context.annotation.ScopeMetadataResolver
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* @see java.util.Optional
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*/
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public Optional<ScopeMetadataResolver> getScopeMetadataResolver() {
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return Optional.ofNullable(this.scopeMetadataResolver);
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}
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protected boolean isUsingDefaultFilters() {
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return USE_DEFAULT_FILTERS;
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}
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@Override
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protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException {
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AnnotatedBeanDefinitionReader reader = configure(newAnnotatedBeanDefinitionReader(beanFactory));
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ClassPathBeanDefinitionScanner scanner = configure(newClassBeanDefinitionScanner(beanFactory));
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getBeanNameGenerator().ifPresent(beanNameGenerator -> {
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reader.setBeanNameGenerator(beanNameGenerator);
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scanner.setBeanNameGenerator(beanNameGenerator);
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beanFactory.registerSingleton(AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR, beanNameGenerator);
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});
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getScopeMetadataResolver().ifPresent(scopeMetadataResolver -> {
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reader.setScopeMetadataResolver(scopeMetadataResolver);
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scanner.setScopeMetadataResolver(scopeMetadataResolver);
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});
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Arrays.stream(ArrayUtils.nullSafeArray(getConfigLocations(), String.class)).forEach(configLocation -> {
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try {
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Class<?> type = ClassUtils.forName(configLocation, getClassLoader());
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getLogger().trace("Registering [{}]", configLocation);
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reader.register(type);
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}
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catch (ClassNotFoundException cause) {
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getLogger().trace(String.format("Could not load class for config location [%s] - trying package scan.",
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configLocation), cause);
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if (scanner.scan(configLocation) == 0) {
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getLogger().debug("No component classes found for specified class/package [{}]", configLocation);
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}
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}
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});
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}
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private AnnotatedBeanDefinitionReader configure(AnnotatedBeanDefinitionReader reader) {
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Set<Class<?>> componentClasses = this.componentClasses;
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if (!componentClasses.isEmpty()) {
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getLogger().debug("Registering component classes: {}", componentClasses);
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reader.register(ClassUtils.toClassArray(componentClasses));
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}
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return reader;
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}
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private ClassPathBeanDefinitionScanner configure(ClassPathBeanDefinitionScanner scanner) {
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Set<String> basePackages = this.basePackages;
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if (!basePackages.isEmpty()) {
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getLogger().debug("Scanning base packages: {}", basePackages);
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scanner.scan(StringUtils.toStringArray(basePackages));
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}
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return scanner;
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}
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// TODO: Not entirely certain this is a good idea (yet); However, it does follow the BeanFactory creation pattern
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// used by // the GenericApplicationContext (& extensions, e.g. AnnotationConfigApplicationContext) that I am
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// trying to // preserve in this RefreshableAnnotationConfigApplicationContext implementation. However, the
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// AnnotationConfigApplicationContext implementation is NOT refreshable either, although
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// AnnotationConfigWebApplicationContext is, so... hmm!
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// This overridden createBeanFactory() method effectively maintains the BeanFactory as a Singleton!
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@Override
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protected synchronized DefaultListableBeanFactory createBeanFactory() {
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if (this.beanFactory == null) {
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this.beanFactory = super.createBeanFactory();
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}
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return this.beanFactory;
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}
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protected AnnotatedBeanDefinitionReader newAnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry) {
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return new AnnotatedBeanDefinitionReader(registry, getEnvironment());
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}
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protected ClassPathBeanDefinitionScanner newClassBeanDefinitionScanner(BeanDefinitionRegistry registry) {
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return new ClassPathBeanDefinitionScanner(registry, isUsingDefaultFilters(), getEnvironment());
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}
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/**
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* @inheritDoc
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*/
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@Override
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public void register(Class<?>... componentClasses) {
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Arrays.stream(ArrayUtils.nullSafeArray(componentClasses, Class.class))
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.filter(Objects::nonNull)
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.forEach(this.componentClasses::add);
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}
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/**
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* @inheritDoc
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*/
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@Override
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public void scan(String... basePackages) {
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Arrays.stream(ArrayUtils.nullSafeArray(basePackages, String.class))
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.filter(StringUtils::hasText)
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.forEach(this.basePackages::add);
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}
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}
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