spring ClassPathScanningCandidateComponentProvider 源码
spring ClassPathScanningCandidateComponentProvider 代码
文件路径：/spring-context/src/main/java/org/springframework/context/annotation/ClassPathScanningCandidateComponentProvider.java
/*
* Copyright 2002-2021 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.FileNotFoundException;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition;
import org.springframework.beans.factory.annotation.Lookup;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.context.index.CandidateComponentsIndex;
import org.springframework.context.index.CandidateComponentsIndexLoader;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.core.env.Environment;
import org.springframework.core.env.EnvironmentCapable;
import org.springframework.core.env.StandardEnvironment;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternUtils;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.core.type.filter.AssignableTypeFilter;
import org.springframework.core.type.filter.TypeFilter;
import org.springframework.lang.Nullable;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Indexed;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* A component provider that provides candidate components from a base package. Can
* use {@link CandidateComponentsIndex the index} if it is available of scans the
* classpath otherwise. Candidate components are identified by applying exclude and
* include filters. {@link AnnotationTypeFilter}, {@link AssignableTypeFilter} include
* filters on an annotation/superclass that are annotated with {@link Indexed} are
* supported: if any other include filter is specified, the index is ignored and
* classpath scanning is used instead.
*
* <p>This implementation is based on Spring's
* {@link org.springframework.core.type.classreading.MetadataReader MetadataReader}
* facility, backed by an ASM {@link org.springframework.asm.ClassReader ClassReader}.
*
* @author Mark Fisher
* @author Juergen Hoeller
* @author Ramnivas Laddad
* @author Chris Beams
* @author Stephane Nicoll
* @since 2.5
* @see org.springframework.core.type.classreading.MetadataReaderFactory
* @see org.springframework.core.type.AnnotationMetadata
* @see ScannedGenericBeanDefinition
* @see CandidateComponentsIndex
*/
public class ClassPathScanningCandidateComponentProvider implements EnvironmentCapable, ResourceLoaderAware {
static final String DEFAULT_RESOURCE_PATTERN = "**/*.class";
protected final Log logger = LogFactory.getLog(getClass());
private String resourcePattern = DEFAULT_RESOURCE_PATTERN;
private final List<TypeFilter> includeFilters = new ArrayList<>();
private final List<TypeFilter> excludeFilters = new ArrayList<>();
@Nullable
private Environment environment;
@Nullable
private ConditionEvaluator conditionEvaluator;
@Nullable
private ResourcePatternResolver resourcePatternResolver;
@Nullable
private MetadataReaderFactory metadataReaderFactory;
@Nullable
private CandidateComponentsIndex componentsIndex;
/**
* Protected constructor for flexible subclass initialization.
* @since 4.3.6
*/
protected ClassPathScanningCandidateComponentProvider() {
}
/**
* Create a ClassPathScanningCandidateComponentProvider with a {@link StandardEnvironment}.
* @param useDefaultFilters whether to register the default filters for the
* {@link Component @Component}, {@link Repository @Repository},
* {@link Service @Service}, and {@link Controller @Controller}
* stereotype annotations
* @see #registerDefaultFilters()
*/
public ClassPathScanningCandidateComponentProvider(boolean useDefaultFilters) {
this(useDefaultFilters, new StandardEnvironment());
}
/**
* Create a ClassPathScanningCandidateComponentProvider with the given {@link Environment}.
* @param useDefaultFilters whether to register the default filters for the
* {@link Component @Component}, {@link Repository @Repository},
* {@link Service @Service}, and {@link Controller @Controller}
* stereotype annotations
* @param environment the Environment to use
* @see #registerDefaultFilters()
*/
public ClassPathScanningCandidateComponentProvider(boolean useDefaultFilters, Environment environment) {
if (useDefaultFilters) {
registerDefaultFilters();
}
setEnvironment(environment);
setResourceLoader(null);
}
/**
* Set the resource pattern to use when scanning the classpath.
* This value will be appended to each base package name.
* @see #findCandidateComponents(String)
* @see #DEFAULT_RESOURCE_PATTERN
*/
public void setResourcePattern(String resourcePattern) {
Assert.notNull(resourcePattern, "'resourcePattern' must not be null");
this.resourcePattern = resourcePattern;
}
/**
* Add an include type filter to the <i>end</i> of the inclusion list.
*/
public void addIncludeFilter(TypeFilter includeFilter) {
this.includeFilters.add(includeFilter);
}
/**
* Add an exclude type filter to the <i>front</i> of the exclusion list.
*/
public void addExcludeFilter(TypeFilter excludeFilter) {
this.excludeFilters.add(0, excludeFilter);
}
/**
* Reset the configured type filters.
* @param useDefaultFilters whether to re-register the default filters for
* the {@link Component @Component}, {@link Repository @Repository},
* {@link Service @Service}, and {@link Controller @Controller}
* stereotype annotations
* @see #registerDefaultFilters()
*/
public void resetFilters(boolean useDefaultFilters) {
this.includeFilters.clear();
this.excludeFilters.clear();
if (useDefaultFilters) {
registerDefaultFilters();
}
}
/**
* Register the default filter for {@link Component @Component}.
* <p>This will implicitly register all annotations that have the
* {@link Component @Component} meta-annotation including the
* {@link Repository @Repository}, {@link Service @Service}, and
* {@link Controller @Controller} stereotype annotations.
* <p>Also supports Jakarta EE's {@link jakarta.annotation.ManagedBean} and
* JSR-330's {@link jakarta.inject.Named} annotations, if available.
*
*/
@SuppressWarnings("unchecked")
protected void registerDefaultFilters() {
this.includeFilters.add(new AnnotationTypeFilter(Component.class));
ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();
try {
this.includeFilters.add(new AnnotationTypeFilter(
((Class<? extends Annotation>) ClassUtils.forName("jakarta.annotation.ManagedBean", cl)), false));
logger.trace("JSR-250 'jakarta.annotation.ManagedBean' found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-250 1.1 API (as included in Jakarta EE) not available - simply skip.
}
try {
this.includeFilters.add(new AnnotationTypeFilter(
((Class<? extends Annotation>) ClassUtils.forName("jakarta.inject.Named", cl)), false));
logger.trace("JSR-330 'jakarta.inject.Named' annotation found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - simply skip.
}
}
/**
* Set the Environment to use when resolving placeholders and evaluating
* {@link Conditional @Conditional}-annotated component classes.
* <p>The default is a {@link StandardEnvironment}.
* @param environment the Environment to use
*/
public void setEnvironment(Environment environment) {
Assert.notNull(environment, "Environment must not be null");
this.environment = environment;
this.conditionEvaluator = null;
}
@Override
public final Environment getEnvironment() {
if (this.environment == null) {
this.environment = new StandardEnvironment();
}
return this.environment;
}
/**
* Return the {@link BeanDefinitionRegistry} used by this scanner, if any.
*/
@Nullable
protected BeanDefinitionRegistry getRegistry() {
return null;
}
/**
* Set the {@link ResourceLoader} to use for resource locations.
* This will typically be a {@link ResourcePatternResolver} implementation.
* <p>Default is a {@code PathMatchingResourcePatternResolver}, also capable of
* resource pattern resolving through the {@code ResourcePatternResolver} interface.
* @see org.springframework.core.io.support.ResourcePatternResolver
* @see org.springframework.core.io.support.PathMatchingResourcePatternResolver
*/
@Override
public void setResourceLoader(@Nullable ResourceLoader resourceLoader) {
this.resourcePatternResolver = ResourcePatternUtils.getResourcePatternResolver(resourceLoader);
this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);
this.componentsIndex = CandidateComponentsIndexLoader.loadIndex(this.resourcePatternResolver.getClassLoader());
}
/**
* Return the ResourceLoader that this component provider uses.
*/
public final ResourceLoader getResourceLoader() {
return getResourcePatternResolver();
}
private ResourcePatternResolver getResourcePatternResolver() {
if (this.resourcePatternResolver == null) {
this.resourcePatternResolver = new PathMatchingResourcePatternResolver();
}
return this.resourcePatternResolver;
}
/**
* Set the {@link MetadataReaderFactory} to use.
* <p>Default is a {@link CachingMetadataReaderFactory} for the specified
* {@linkplain #setResourceLoader resource loader}.
* <p>Call this setter method <i>after</i> {@link #setResourceLoader} in order
* for the given MetadataReaderFactory to override the default factory.
*/
public void setMetadataReaderFactory(MetadataReaderFactory metadataReaderFactory) {
this.metadataReaderFactory = metadataReaderFactory;
}
/**
* Return the MetadataReaderFactory used by this component provider.
*/
public final MetadataReaderFactory getMetadataReaderFactory() {
if (this.metadataReaderFactory == null) {
this.metadataReaderFactory = new CachingMetadataReaderFactory();
}
return this.metadataReaderFactory;
}
/**
* Scan the class path for candidate components.
* @param basePackage the package to check for annotated classes
* @return a corresponding Set of autodetected bean definitions
*/
public Set<BeanDefinition> findCandidateComponents(String basePackage) {
if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
}
else {
return scanCandidateComponents(basePackage);
}
}
/**
* Determine if the index can be used by this instance.
* @return {@code true} if the index is available and the configuration of this
* instance is supported by it, {@code false} otherwise
* @since 5.0
*/
private boolean indexSupportsIncludeFilters() {
for (TypeFilter includeFilter : this.includeFilters) {
if (!indexSupportsIncludeFilter(includeFilter)) {
return false;
}
}
return true;
}
/**
* Determine if the specified include {@link TypeFilter} is supported by the index.
* @param filter the filter to check
* @return whether the index supports this include filter
* @since 5.0
* @see #extractStereotype(TypeFilter)
*/
private boolean indexSupportsIncludeFilter(TypeFilter filter) {
if (filter instanceof AnnotationTypeFilter) {
Class<? extends Annotation> annotation = ((AnnotationTypeFilter) filter).getAnnotationType();
return (AnnotationUtils.isAnnotationDeclaredLocally(Indexed.class, annotation) ||
annotation.getName().startsWith("javax."));
}
if (filter instanceof AssignableTypeFilter) {
Class<?> target = ((AssignableTypeFilter) filter).getTargetType();
return AnnotationUtils.isAnnotationDeclaredLocally(Indexed.class, target);
}
return false;
}
/**
* Extract the stereotype to use for the specified compatible filter.
* @param filter the filter to handle
* @return the stereotype in the index matching this filter
* @since 5.0
* @see #indexSupportsIncludeFilter(TypeFilter)
*/
@Nullable
private String extractStereotype(TypeFilter filter) {
if (filter instanceof AnnotationTypeFilter) {
return ((AnnotationTypeFilter) filter).getAnnotationType().getName();
}
if (filter instanceof AssignableTypeFilter) {
return ((AssignableTypeFilter) filter).getTargetType().getName();
}
return null;
}
private Set<BeanDefinition> addCandidateComponentsFromIndex(CandidateComponentsIndex index, String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
Set<String> types = new HashSet<>();
for (TypeFilter filter : this.includeFilters) {
String stereotype = extractStereotype(filter);
if (stereotype == null) {
throw new IllegalArgumentException("Failed to extract stereotype from " + filter);
}
types.addAll(index.getCandidateTypes(basePackage, stereotype));
}
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
for (String type : types) {
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(type);
if (isCandidateComponent(metadataReader)) {
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setSource(metadataReader.getResource());
if (isCandidateComponent(sbd)) {
if (debugEnabled) {
logger.debug("Using candidate component class from index: " + type);
}
candidates.add(sbd);
}
else {
if (debugEnabled) {
logger.debug("Ignored because not a concrete top-level class: " + type);
}
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because matching an exclude filter: " + type);
}
}
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
for (Resource resource : resources) {
if (traceEnabled) {
logger.trace("Scanning " + resource);
}
try {
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
if (isCandidateComponent(metadataReader)) {
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setSource(resource);
if (isCandidateComponent(sbd)) {
if (debugEnabled) {
logger.debug("Identified candidate component class: " + resource);
}
candidates.add(sbd);
}
else {
if (debugEnabled) {
logger.debug("Ignored because not a concrete top-level class: " + resource);
}
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not matching any filter: " + resource);
}
}
}
catch (FileNotFoundException ex) {
if (traceEnabled) {
logger.trace("Ignored non-readable " + resource + ": " + ex.getMessage());
}
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to read candidate component class: " + resource, ex);
}
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
/**
* Resolve the specified base package into a pattern specification for
* the package search path.
* <p>The default implementation resolves placeholders against system properties,
* and converts a "."-based package path to a "/"-based resource path.
* @param basePackage the base package as specified by the user
* @return the pattern specification to be used for package searching
*/
protected String resolveBasePackage(String basePackage) {
return ClassUtils.convertClassNameToResourcePath(getEnvironment().resolveRequiredPlaceholders(basePackage));
}
/**
* Determine whether the given class does not match any exclude filter
* and does match at least one include filter.
* @param metadataReader the ASM ClassReader for the class
* @return whether the class qualifies as a candidate component
*/
protected boolean isCandidateComponent(MetadataReader metadataReader) throws IOException {
for (TypeFilter tf : this.excludeFilters) {
if (tf.match(metadataReader, getMetadataReaderFactory())) {
return false;
}
}
for (TypeFilter tf : this.includeFilters) {
if (tf.match(metadataReader, getMetadataReaderFactory())) {
return isConditionMatch(metadataReader);
}
}
return false;
}
/**
* Determine whether the given class is a candidate component based on any
* {@code @Conditional} annotations.
* @param metadataReader the ASM ClassReader for the class
* @return whether the class qualifies as a candidate component
*/
private boolean isConditionMatch(MetadataReader metadataReader) {
if (this.conditionEvaluator == null) {
this.conditionEvaluator =
new ConditionEvaluator(getRegistry(), this.environment, this.resourcePatternResolver);
}
return !this.conditionEvaluator.shouldSkip(metadataReader.getAnnotationMetadata());
}
/**
* Determine whether the given bean definition qualifies as candidate.
* <p>The default implementation checks whether the class is not an interface
* and not dependent on an enclosing class.
* <p>Can be overridden in subclasses.
* @param beanDefinition the bean definition to check
* @return whether the bean definition qualifies as a candidate component
*/
protected boolean isCandidateComponent(AnnotatedBeanDefinition beanDefinition) {
AnnotationMetadata metadata = beanDefinition.getMetadata();
return (metadata.isIndependent() && (metadata.isConcrete() ||
(metadata.isAbstract() && metadata.hasAnnotatedMethods(Lookup.class.getName()))));
}
/**
* Clear the local metadata cache, if any, removing all cached class metadata.
*/
public void clearCache() {
if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
// Clear cache in externally provided MetadataReaderFactory; this is a no-op
// for a shared cache since it'll be cleared by the ApplicationContext.
((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
}
}
}
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