org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider Maven / Gradle / Ivy
/*
* Copyright 2002-2014 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.context.annotation;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.util.LinkedHashSet;
import java.util.LinkedList;
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.config.BeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.ResourceLoaderAware;
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.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.TypeFilter;
import org.springframework.stereotype.Component;
import org.springframework.stereotype.Controller;
import org.springframework.stereotype.Repository;
import org.springframework.stereotype.Service;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
/**
* A component provider that scans the classpath from a base package. It then
* applies exclude and include filters to the resulting classes to find candidates.
*
* 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
* @since 2.5
* @see org.springframework.core.type.classreading.MetadataReaderFactory
* @see org.springframework.core.type.AnnotationMetadata
* @see ScannedGenericBeanDefinition
*/
public class ClassPathScanningCandidateComponentProvider implements EnvironmentCapable, ResourceLoaderAware {
static final String DEFAULT_RESOURCE_PATTERN = "**/*.class";
protected final Log logger = LogFactory.getLog(getClass());
private Environment environment;
private ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
private MetadataReaderFactory metadataReaderFactory =
new CachingMetadataReaderFactory(this.resourcePatternResolver);
private String resourcePattern = DEFAULT_RESOURCE_PATTERN;
private final List includeFilters = new LinkedList();
private final List excludeFilters = new LinkedList();
private ConditionEvaluator conditionEvaluator;
/**
* 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();
}
Assert.notNull(environment, "Environment must not be null");
this.environment = environment;
}
/**
* Set the ResourceLoader to use for resource locations.
* This will typically be a ResourcePatternResolver implementation.
* Default is PathMatchingResourcePatternResolver, also capable of
* resource pattern resolving through the ResourcePatternResolver interface.
* @see org.springframework.core.io.support.ResourcePatternResolver
* @see org.springframework.core.io.support.PathMatchingResourcePatternResolver
*/
@Override
public void setResourceLoader(ResourceLoader resourceLoader) {
this.resourcePatternResolver = ResourcePatternUtils.getResourcePatternResolver(resourceLoader);
this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);
}
/**
* Return the ResourceLoader that this component provider uses.
*/
public final ResourceLoader getResourceLoader() {
return this.resourcePatternResolver;
}
/**
* Set the {@link MetadataReaderFactory} to use.
*
Default is a {@link CachingMetadataReaderFactory} for the specified
* {@linkplain #setResourceLoader resource loader}.
*
Call this setter method after {@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() {
return this.metadataReaderFactory;
}
/**
* Set the Environment to use when resolving placeholders and evaluating
* {@link Conditional @Conditional}-annotated component classes.
*
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() {
return this.environment;
}
/**
* Returns the {@link BeanDefinitionRegistry} used by this scanner, if any.
*/
protected BeanDefinitionRegistry getRegistry() {
return 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 end of the inclusion list.
*/
public void addIncludeFilter(TypeFilter includeFilter) {
this.includeFilters.add(includeFilter);
}
/**
* Add an exclude type filter to the front 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}.
*
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.
*
Also supports Java EE 6's {@link javax.annotation.ManagedBean} and
* JSR-330's {@link javax.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) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));
logger.debug("JSR-250 'javax.annotation.ManagedBean' found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-250 1.1 API (as included in Java EE 6) not available - simply skip.
}
try {
this.includeFilters.add(new AnnotationTypeFilter(
((Class) ClassUtils.forName("javax.inject.Named", cl)), false));
logger.debug("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - simply skip.
}
}
/**
* 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 findCandidateComponents(String basePackage) {
Set candidates = new LinkedHashSet();
try {
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + "/" + this.resourcePattern;
Resource[] resources = this.resourcePatternResolver.getResources(packageSearchPath);
boolean traceEnabled = logger.isTraceEnabled();
boolean debugEnabled = logger.isDebugEnabled();
for (Resource resource : resources) {
if (traceEnabled) {
logger.trace("Scanning " + resource);
}
if (resource.isReadable()) {
try {
MetadataReader metadataReader = this.metadataReaderFactory.getMetadataReader(resource);
if (isCandidateComponent(metadataReader)) {
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setResource(resource);
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 (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to read candidate component class: " + resource, ex);
}
}
else {
if (traceEnabled) {
logger.trace("Ignored because not readable: " + resource);
}
}
}
}
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.
* 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(this.environment.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, this.metadataReaderFactory)) {
return false;
}
}
for (TypeFilter tf : this.includeFilters) {
if (tf.match(metadataReader, this.metadataReaderFactory)) {
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(), getEnvironment(), getResourceLoader());
}
return !this.conditionEvaluator.shouldSkip(metadataReader.getAnnotationMetadata());
}
/**
* Determine whether the given bean definition qualifies as candidate.
*
The default implementation checks whether the class is concrete
* (i.e. not abstract and not an interface). 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) {
return (beanDefinition.getMetadata().isConcrete() && beanDefinition.getMetadata().isIndependent());
}
/**
* Clear the underlying metadata cache, removing all cached class metadata.
*/
public void clearCache() {
if (this.metadataReaderFactory instanceof CachingMetadataReaderFactory) {
((CachingMetadataReaderFactory) this.metadataReaderFactory).clearCache();
}
}
}