Java tutorial
/* * Copyright 2012-2019 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 * * http://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.boot.web.servlet.context; import java.lang.annotation.Annotation; import java.util.Arrays; import java.util.LinkedHashSet; import java.util.Set; import java.util.function.Supplier; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.factory.config.ConfigurableListableBeanFactory; import org.springframework.beans.factory.support.BeanNameGenerator; import org.springframework.beans.factory.support.DefaultListableBeanFactory; import org.springframework.context.annotation.AnnotatedBeanDefinitionReader; import org.springframework.context.annotation.AnnotationConfigRegistry; import org.springframework.context.annotation.AnnotationConfigUtils; import org.springframework.context.annotation.AnnotationScopeMetadataResolver; import org.springframework.context.annotation.ClassPathBeanDefinitionScanner; import org.springframework.context.annotation.ScopeMetadataResolver; import org.springframework.core.env.ConfigurableEnvironment; import org.springframework.stereotype.Component; import org.springframework.util.Assert; import org.springframework.util.ClassUtils; import org.springframework.util.StringUtils; import org.springframework.web.context.support.AnnotationConfigWebApplicationContext; /** * {@link ServletWebServerApplicationContext} that accepts annotated classes as input - in * particular {@link org.springframework.context.annotation.Configuration @Configuration} * -annotated classes, but also plain {@link Component @Component} classes and JSR-330 * compliant classes using {@code javax.inject} annotations. Allows for registering * classes one by one (specifying class names as config location) as well as for classpath * scanning (specifying base packages as config location). * <p> * Note: In case of multiple {@code @Configuration} classes, later {@code @Bean} * definitions will override ones defined in earlier loaded files. This can be leveraged * to deliberately override certain bean definitions via an extra Configuration class. * * @author Phillip Webb * @see #register(Class...) * @see #scan(String...) * @see ServletWebServerApplicationContext * @see AnnotationConfigWebApplicationContext */ public class AnnotationConfigServletWebServerApplicationContext extends ServletWebServerApplicationContext implements AnnotationConfigRegistry { private final Log logger = LogFactory.getLog(getClass()); private final AnnotatedBeanDefinitionReader reader; private final ClassPathBeanDefinitionScanner scanner; private final Set<Class<?>> annotatedClasses = new LinkedHashSet<>(); private String[] basePackages; private final Set<BeanRegistration> registeredBeans = new LinkedHashSet<>(); /** * Create a new {@link AnnotationConfigServletWebServerApplicationContext} that needs * to be populated through {@link #register} calls and then manually * {@linkplain #refresh refreshed}. */ public AnnotationConfigServletWebServerApplicationContext() { this.reader = new AnnotatedBeanDefinitionReader(this); this.scanner = new ClassPathBeanDefinitionScanner(this); } /** * Create a new {@link AnnotationConfigServletWebServerApplicationContext} with the * given {@code DefaultListableBeanFactory}. The context needs to be populated through * {@link #register} calls and then manually {@linkplain #refresh refreshed}. * @param beanFactory the DefaultListableBeanFactory instance to use for this context */ public AnnotationConfigServletWebServerApplicationContext(DefaultListableBeanFactory beanFactory) { super(beanFactory); this.reader = new AnnotatedBeanDefinitionReader(this); this.scanner = new ClassPathBeanDefinitionScanner(this); } /** * Create a new {@link AnnotationConfigServletWebServerApplicationContext}, deriving * bean definitions from the given annotated classes and automatically refreshing the * context. * @param annotatedClasses one or more annotated classes, e.g. {@code @Configuration} * classes */ public AnnotationConfigServletWebServerApplicationContext(Class<?>... annotatedClasses) { this(); register(annotatedClasses); refresh(); } /** * Create a new {@link AnnotationConfigServletWebServerApplicationContext}, scanning * for bean definitions in the given packages and automatically refreshing the * context. * @param basePackages the packages to check for annotated classes */ public AnnotationConfigServletWebServerApplicationContext(String... basePackages) { this(); scan(basePackages); refresh(); } /** * {@inheritDoc} * <p> * Delegates given environment to underlying {@link AnnotatedBeanDefinitionReader} and * {@link ClassPathBeanDefinitionScanner} members. */ @Override public void setEnvironment(ConfigurableEnvironment environment) { super.setEnvironment(environment); this.reader.setEnvironment(environment); this.scanner.setEnvironment(environment); } /** * Provide a custom {@link BeanNameGenerator} for use with * {@link AnnotatedBeanDefinitionReader} and/or * {@link ClassPathBeanDefinitionScanner}, if any. * <p> * Default is * {@link org.springframework.context.annotation.AnnotationBeanNameGenerator}. * <p> * Any call to this method must occur prior to calls to {@link #register(Class...)} * and/or {@link #scan(String...)}. * @param beanNameGenerator the bean name generator * @see AnnotatedBeanDefinitionReader#setBeanNameGenerator * @see ClassPathBeanDefinitionScanner#setBeanNameGenerator */ public void setBeanNameGenerator(BeanNameGenerator beanNameGenerator) { this.reader.setBeanNameGenerator(beanNameGenerator); this.scanner.setBeanNameGenerator(beanNameGenerator); this.getBeanFactory().registerSingleton(AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR, beanNameGenerator); } /** * Set the {@link ScopeMetadataResolver} to use for detected bean classes. * <p> * The default is an {@link AnnotationScopeMetadataResolver}. * <p> * Any call to this method must occur prior to calls to {@link #register(Class...)} * and/or {@link #scan(String...)}. * @param scopeMetadataResolver the scope metadata resolver */ public void setScopeMetadataResolver(ScopeMetadataResolver scopeMetadataResolver) { this.reader.setScopeMetadataResolver(scopeMetadataResolver); this.scanner.setScopeMetadataResolver(scopeMetadataResolver); } /** * Register one or more annotated classes to be processed. Note that * {@link #refresh()} must be called in order for the context to fully process the new * class. * <p> * Calls to {@code #register} are idempotent; adding the same annotated class more * than once has no additional effect. * @param annotatedClasses one or more annotated classes, e.g. {@code @Configuration} * classes * @see #scan(String...) * @see #refresh() */ @Override public final void register(Class<?>... annotatedClasses) { Assert.notEmpty(annotatedClasses, "At least one annotated class must be specified"); this.annotatedClasses.addAll(Arrays.asList(annotatedClasses)); } /** * Perform a scan within the specified base packages. Note that {@link #refresh()} * must be called in order for the context to fully process the new class. * @param basePackages the packages to check for annotated classes * @see #register(Class...) * @see #refresh() */ @Override public final void scan(String... basePackages) { Assert.notEmpty(basePackages, "At least one base package must be specified"); this.basePackages = basePackages; } /** * Register a bean from the given bean class. * @param annotatedClass the class of the bean * @param <T> the type of the bean * @since 2.2.0 */ public final <T> void registerBean(Class<T> annotatedClass) { this.registeredBeans.add(new BeanRegistration(annotatedClass, null, null)); } /** * Register a bean from the given bean class, using the given supplier for obtaining a * new instance (typically declared as a lambda expression or method reference). * @param annotatedClass the class of the bean * @param supplier a callback for creating an instance of the bean * @param <T> the type of the bean * @since 2.2.0 */ public final <T> void registerBean(Class<T> annotatedClass, Supplier<T> supplier) { this.registeredBeans.add(new BeanRegistration(annotatedClass, supplier, null)); } @Override @SafeVarargs @SuppressWarnings("varargs") public final <T> void registerBean(Class<T> annotatedClass, Class<? extends Annotation>... qualifiers) { this.registeredBeans.add(new BeanRegistration(annotatedClass, null, qualifiers)); } @Override @SafeVarargs @SuppressWarnings("varargs") public final <T> void registerBean(Class<T> annotatedClass, Supplier<T> supplier, Class<? extends Annotation>... qualifiers) { this.registeredBeans.add(new BeanRegistration(annotatedClass, supplier, qualifiers)); } @Override protected void prepareRefresh() { this.scanner.clearCache(); super.prepareRefresh(); } @Override protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) { super.postProcessBeanFactory(beanFactory); if (this.basePackages != null && this.basePackages.length > 0) { this.scanner.scan(this.basePackages); } if (!this.annotatedClasses.isEmpty()) { this.reader.register(ClassUtils.toClassArray(this.annotatedClasses)); } if (!this.registeredBeans.isEmpty()) { registerBeans(this.reader); } } private void registerBeans(AnnotatedBeanDefinitionReader reader) { if (this.logger.isDebugEnabled()) { this.logger.debug("Registering supplied beans: [" + StringUtils.collectionToCommaDelimitedString(this.registeredBeans) + "]"); } this.registeredBeans.forEach( (reg) -> reader.registerBean(reg.getAnnotatedClass(), reg.getSupplier(), reg.getQualifiers())); } /** * Holder for a programmatic bean registration. * * @see #registerBean(Class, Class[]) * @see #registerBean(Class, Supplier, Class[]) */ private static class BeanRegistration { private final Class<?> annotatedClass; private final Supplier<?> supplier; private final Class<? extends Annotation>[] qualifiers; BeanRegistration(Class<?> annotatedClass, Supplier<?> supplier, Class<? extends Annotation>[] qualifiers) { this.annotatedClass = annotatedClass; this.supplier = supplier; this.qualifiers = qualifiers; } public Class<?> getAnnotatedClass() { return this.annotatedClass; } @SuppressWarnings("rawtypes") public Supplier getSupplier() { return this.supplier; } public Class<? extends Annotation>[] getQualifiers() { return this.qualifiers; } @Override public String toString() { return this.annotatedClass.getName(); } } }