SpringScan

Posted 2021-03-17 龙X

 

 

ClassPathBeanDefinitionScanner.java

/**
     * Perform a scan within the specified base packages,
     * returning the registered bean definitions.
     * <p>This method does <i>not</i> register an annotation config processor
     * but rather leaves this up to the caller.
     * @param basePackages the packages to check for annotated classes
     * @return set of beans registered if any for tooling registration purposes (never {@code null})
     */
    protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
        Assert.notEmpty(basePackages, "At least one base package must be specified");
        Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<BeanDefinitionHolder>();
        for (String basePackage : basePackages) {
            Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
            for (BeanDefinition candidate : candidates) {
                ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
                candidate.setScope(scopeMetadata.getScopeName());
                String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
                if (candidate instanceof AbstractBeanDefinition) {
                    postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
                }
                if (candidate instanceof AnnotatedBeanDefinition) {
                    AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
                }
                if (checkCandidate(beanName, candidate)) {
                    BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(candidate, beanName);
                    definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
                    beanDefinitions.add(definitionHolder);
                    registerBeanDefinition(definitionHolder, this.registry);
                }
            }
        }
        return beanDefinitions;
    }

 

ClassPathScanningCandidateComponentProvider.java

/**
     * 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) {
        Set<BeanDefinition> candidates = new LinkedHashSet<BeanDefinition>();
        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;
    }

/**
 * 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;
}

 

ResourcePatternResolver.java

/**
 * Strategy interface for resolving a location pattern (for example,
 * an Ant-style path pattern) into Resource objects.
 *
 * <p>This is an extension to the {@link org.springframework.core.io.ResourceLoader}
 * interface. A passed-in ResourceLoader (for example, an
 * {@link org.springframework.context.ApplicationContext} passed in via
 * {@link org.springframework.context.ResourceLoaderAware} when running in a context)
 * can be checked whether it implements this extended interface too.
 *
 * <p>{@link PathMatchingResourcePatternResolver} is a standalone implementation
 * that is usable outside an ApplicationContext, also used by
 * {@link ResourceArrayPropertyEditor} for populating Resource array bean properties.
 *
 * <p>Can be used with any sort of location pattern (e.g. "/WEB-INF/*-context.xml"):
 * Input patterns have to match the strategy implementation. This interface just
 * specifies the conversion method rather than a specific pattern format.
 *
 * <p>This interface also suggests a new resource prefix "classpath*:" for all
 * matching resources from the class path. Note that the resource location is
 * expected to be a path without placeholders in this case (e.g. "/beans.xml");
 * JAR files or classes directories can contain multiple files of the same name.
 *
 * @author Juergen Hoeller
 * @since 1.0.2
 * @see org.springframework.core.io.Resource
 * @see org.springframework.core.io.ResourceLoader
 * @see org.springframework.context.ApplicationContext
 * @see org.springframework.context.ResourceLoaderAware
 */

public interface ResourcePatternResolver extends ResourceLoader {

/**
 * Pseudo URL prefix for all matching resources from the class path: "classpath*:"
 * This differs from ResourceLoader‘s classpath URL prefix in that it
 * retrieves all matching resources for a given name (e.g. "/beans.xml"),
 * for example in the root of all deployed JAR files.
 * @see org.springframework.core.io.ResourceLoader#CLASSPATH_URL_PREFIX
 */
String CLASSPATH_ALL_URL_PREFIX = "classpath*:";

/**
 * Resolve the given location pattern into Resource objects.
 * <p>Overlapping resource entries that point to the same physical
 * resource should be avoided, as far as possible. The result should
 * have set semantics.
 * @param locationPattern the location pattern to resolve
 * @return the corresponding Resource objects
 * @throws IOException in case of I/O errors
 */
Resource[] getResources(String locationPattern) throws IOException;

}

 

 

PathMatchingResourcePatternResolver.java

@Override
    public Resource[] getResources(String locationPattern) throws IOException {
        Assert.notNull(locationPattern, "Location pattern must not be null");
        if (locationPattern.startsWith(CLASSPATH_ALL_URL_PREFIX)) {
            // a class path resource (multiple resources for same name possible)
            if (getPathMatcher().isPattern(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()))) {
                // a class path resource pattern
                return findPathMatchingResources(locationPattern);
            }
            else {
                // all class path resources with the given name
                return findAllClassPathResources(locationPattern.substring(CLASSPATH_ALL_URL_PREFIX.length()));
            }
        }
        else {
            // Only look for a pattern after a prefix here
            // (to not get fooled by a pattern symbol in a strange prefix).
            int prefixEnd = locationPattern.indexOf(":") + 1;
            if (getPathMatcher().isPattern(locationPattern.substring(prefixEnd))) {
                // a file pattern
                return findPathMatchingResources(locationPattern);
            }
            else {
                // a single resource with the given name
                return new Resource[] {getResourceLoader().getResource(locationPattern)};
            }
        }
    }

 

/**
     * Find all resources that match the given location pattern via the
     * Ant-style PathMatcher. Supports resources in jar files and zip files
     * and in the file system.
     * @param locationPattern the location pattern to match
     * @return the result as Resource array
     * @throws IOException in case of I/O errors
     * @see #doFindPathMatchingJarResources
     * @see #doFindPathMatchingFileResources
     * @see org.springframework.util.PathMatcher
     */
    protected Resource[] findPathMatchingResources(String locationPattern) throws IOException {
        String rootDirPath = determineRootDir(locationPattern);
        String subPattern = locationPattern.substring(rootDirPath.length());
        Resource[] rootDirResources = getResources(rootDirPath);
        Set<Resource> result = new LinkedHashSet<Resource>(16);
        for (Resource rootDirResource : rootDirResources) {
            rootDirResource = resolveRootDirResource(rootDirResource);
            if (rootDirResource.getURL().getProtocol().startsWith(ResourceUtils.URL_PROTOCOL_VFS)) {
                result.addAll(VfsResourceMatchingDelegate.findMatchingResources(rootDirResource, subPattern, getPathMatcher()));
            }
            else if (isJarResource(rootDirResource)) {
                result.addAll(doFindPathMatchingJarResources(rootDirResource, subPattern));
            }
            else {
                result.addAll(doFindPathMatchingFileResources(rootDirResource, subPattern));
            }
        }
        if (logger.isDebugEnabled()) {
            logger.debug("Resolved location pattern [" + locationPattern + "] to resources " + result);
        }
        return result.toArray(new Resource[result.size()]);
    }