Spring 类路径Bean 扫描之 ClassPathBeanDefinitionScanner
Spring 类路径Bean 扫描之 ClassPathBeanDefinitionScanner
1、简介
从Spring 2.5开始，用户就可以通过编程的方式注册bean，而不用在xml中通过复杂的方式配置bean，这对当时Spring使用者来说是一个天大的惊喜，终于可以告别动辄几千行甚至几万行
的xml配置文件了。 而这一功能的核心是在指定路径扫描带指定注解的bean，并根据自动装配注解完成属性注入。这样用户就只用提供一个basePackage路径，然后在代码上写上适当的注
解就完成所有bean的注入了。ClassPathBeanDefinitionScanner就是一个具备扫描指定路径，并注入对应BeanDefinition能力的工具类。这个类是个非常重要的类，其提供的方法是可以直
接被第三方组件调用的，mybatis 组件就调用了这个方法，用来扫描Mapper接口，并生成代理对象。
官方对这个类的说明是：
ClassPathBeanDefinitionScanner是一个BeanDefinition扫描器，它检测classpath上的bean候选者，使用注册器（BeanFactory或ApplicationContext）注册相应的BeanDefinition。通过
可配置的类型过滤器检测候选类。 默认的类型过滤器含有使用Spring的 @Component，@Repository，@Service 或 @Controller注解的类。还支持Java EE 6的
javax.annotation.ManagedBean 和 JSR-330的javax.inject.Named注解（如果可用）。 只要传递相应的参数实例化了即可使用其扫描bean的能力。可以看到，
ClassPathBeanDefinitionScanner构造函数中最多为4个参，其中重要的有3个，registry是BeanDefinition存储的地方，environment是环境，resourceLoader是类路径相关信息。
2、ClassPathBeanDefinitionScanner 类信息
public class ClassPathBeanDefinitionScanner extends ClassPathScanningCandidateComponentProvider {
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry) {
this(registry, true);
}
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters) {
this(registry, useDefaultFilters, getOrCreateEnvironment(registry));
}
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment) {
this(registry, useDefaultFilters, environment,
(registry instanceof ResourceLoader ? (ResourceLoader) registry : null));
}
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment, @Nullable ResourceLoader resourceLoader) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
this.registry = registry;
if (useDefaultFilters) {
registerDefaultFilters();
}
setEnvironment(environment);
setResourceLoader(resourceLoader);
}
}
从类信息中可以看到真正执行Bean的扫描逻辑的是org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider#findCandidateComponents方法而类路径的Class 匹配是通过PathMatchingResourcePatternResolver类来执行的。
3、基础使用在使用ClassPathBeanDefinitionScanner时，首先需要为其设置registry属性，通常通过构造函数进行设置。DefaultListableBeanFactory 和 GenericApplicationContext都实现了
BeanDefinitionRegistry接口，Spring容器实现类基本上都可以作为registry设置到ClassPathBeanDefinitionScanner中。 然后，通过ClassPathBeanDefinitionScanner#scan()就可以
扫描指定包下的所有类文件，将符合条件的类作为BeanDefinition，注册到registry中。
// 创建registry
BeanDefinitionRegistry registry = new DefaultListableBeanFactory();
// 创建scanner，设置registry
ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(registry);
// 扫描指定包下的bean
scanner.scan("com.example.component");
// 获取bean
BeanFactory beanFactory = (BeanFactory) registry;
Object bean = beanFactory.getBean("xxx");
4、源码解读
4.1、构造函数初始化
我们通常会使用ClassPathBeanDefinitionScanner(BeanDefinitionRegistry)构造函数进行初始化，为其指定registry属性：
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry) {
this(registry, true);
}
在这个过程中，除了registry，还会初始化includeFilters、environment、resourcePatternResolver、metadataReaderFactory和componentsIndex等属性：
public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment, @Nullable ResourceLoader resourceLoader) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
// 初始化registry
this.registry = registry;
// 初始化includeFilters：添加@Component、@ManagedBean和@Named条件
if (useDefaultFilters) {
registerDefaultFilters();
}
// 初始化environment
setEnvironment(environment);
// 初始化resourcePatternResolver、metadataReaderFactory和componentsIndex
setResourceLoader(resourceLoader);
}
在ClassPathScanningCandidateComponentProvider#registerDefaultFilters()方法中，会添加校验@Component、@ManagedBean和@Named三个条件的注解过滤器。
需要注意的是，后两个过滤器只有在引入相关依赖的时候才会生效：
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("javax.annotation.ManagedBean", cl)), false));
logger.trace("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<? extends Annotation>) ClassUtils.forName("javax.inject.Named", cl)), false));
logger.trace("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - simply skip.
}
}
在ClassPathScanningCandidateComponentProvider#setResourceLoader()方法中，会初始化resourcePatternResolver、metadataReaderFactory和componentsIndexpublic void setResourceLoader(@Nullable ResourceLoader resourceLoader) {
this.resourcePatternResolver = ResourcePatternUtils.getResourcePatternResolver(resourceLoader);
this.metadataReaderFactory = new CachingMetadataReaderFactory(resourceLoader);
this.componentsIndex = CandidateComponentsIndexLoader.loadIndex(this.resourcePatternResolver.getClassLoader());
}
在初始化resourcePatternResolver时，会判断registry是否是ResourcePatternResolver实现类（因为ApplicationContext继承了ResourcePatternResolver接口，
而DefaultListableBeanFactory则没有）。如果是，直接将registry赋值给resourcePatternResolver；如果不是，则会新建一个PathMatchingResourcePatternResolver 对象：
public static ResourcePatternResolver getResourcePatternResolver(@Nullable ResourceLoader resourceLoader) {
if (resourceLoader instanceof ResourcePatternResolver) {
return (ResourcePatternResolver) resourceLoader;
}
else if (resourceLoader != null) {
return new PathMatchingResourcePatternResolver(resourceLoader);
}
else {
return new PathMatchingResourcePatternResolver();
}
}
在初始化componentsIndex时，会尝试读取META-INF/spring.components文件中定义的配置信息，componentsIndex对象包含了扫描“META-INF/spring.components”文件后封装起来的需要注册的bean的信息，如果“META-INF/spring.components”文件不存在，则componentsIndex为null。 "META-INF/spring.components" 这个是Spring在5.0版本的时候新增的一个功能。这个文件也可以用来定义需要注册的bean，格式如下:
- 类的全限定名=注解的全限定名 或者 类的全限定名=带有@Indexed注解的类的全限定名
- dw.study.xxxClassName=org.springframework.stereotype.Component
private static CandidateComponentsIndex doLoadIndex(ClassLoader classLoader) {
// 读取spring.index.ignore配置，需要关闭spring.components功能时可以将设为false
if (shouldIgnoreIndex) {
return null;
}
try {
// 读取META-INF/spring.components
Enumeration<URL> urls = classLoader.getResources(COMPONENTS_RESOURCE_LOCATION);
if (!urls.hasMoreElements()) {
return null;
}
// 获取配置
List<Properties> result = new ArrayList<>();
while (urls.hasMoreElements()) {
URL url = urls.nextElement();
Properties properties = PropertiesLoaderUtils.loadProperties(new UrlResource(url));
result.add(properties);
}
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + result.size() + " index(es)");
}
int totalCount = result.stream().mapToInt(Properties::size).sum();
return (totalCount > 0 ? new CandidateComponentsIndex(result) : null);
}
catch (IOException ex) {
throw new IllegalStateException("Unable to load indexes from location [" +
COMPONENTS_RESOURCE_LOCATION + "]", ex);
}
}
4.2、 扫描
4.2.1、scan
通过ClassPathBeanDefinitionScanner#scan()方法可以扫描指定包，注册XxxProcessor，并且计算本次注册bean的数量：
public int scan(String... basePackages) {
int beanCountAtScanStart = this.registry.getBeanDefinitionCount();
// 实际扫描方法
doScan(basePackages);
// 注册XxxProcessor
if (this.includeAnnotationConfig) {
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
return (this.registry.getBeanDefinitionCount() - beanCountAtScanStart);
}
4.2.2、doScan
ClassPathBeanDefinitionScanner#doScan()方法是扫描的核心方法，它会扫描指定包，设置BeanDefinition的基本属性，最后注册到registry中：
protected Set<BeanDefinitionHolder> doScan(String... basePackages) {
Assert.notEmpty(basePackages, "At least one base package must be specified");
Set<BeanDefinitionHolder> beanDefinitions = new LinkedHashSet<>();
// 遍历basePackages
for (String basePackage : basePackages) {
// 从指定basePackage中筛选满足条件的类，解析成BeanDefinition
Set<BeanDefinition> candidates = findCandidateComponents(basePackage);
// 遍历candidates，设置基本属性
for (BeanDefinition candidate : candidates) {
// 设置作用域：读取@Scope属性进行设置
ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(candidate);
candidate.setScope(scopeMetadata.getScopeName());
// 设置beanName：读取@Component属性，或者根据类名生成
String beanName = this.beanNameGenerator.generateBeanName(candidate, this.registry);
// 设置AbstractBeanDefinition相关基本属性
if (candidate instanceof AbstractBeanDefinition) {
postProcessBeanDefinition((AbstractBeanDefinition) candidate, beanName);
}
// 设置AnnotatedBeanDefinition相关基本属性
if (candidate instanceof AnnotatedBeanDefinition) {
AnnotationConfigUtils.processCommonDefinitionAnnotations((AnnotatedBeanDefinition) candidate);
}
// 校验是否重复注册&注册到Spring容器
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;
}
findCandidateComponents
ClassPathScanningCandidateComponentProvider#findCandidateComponents()包含扫描包的核心代码。
如果开启了spring.components配置，并且includeFilters中只有@Indexed及其子注解条件（或者注解全限定类名以javax.开头），就会从spring.components中扫描满足条件的类
进行解析。如果没有开启spring.component配置，或者includeFilters不满足条件，就会从类路径中扫描满足条件的类进行解析。
ClassPathScanningCandidateComponentProvider#findCandidateComponents()源码如下：
public Set<BeanDefinition> findCandidateComponents(String basePackage) {
// 开启spring.components配置，并且includeFilters过滤器仅支持@Indexed及其子注解条件时：从配置中扫描
if (this.componentsIndex != null && indexSupportsIncludeFilters()) {
return addCandidateComponentsFromIndex(this.componentsIndex, basePackage);
}
// 从指定包中扫描
else {
return scanCandidateComponents(basePackage);
}
}
4.2.3、扫描spring.components
我们先来看ClassPathScanningCandidateComponentProvider#addCandidateComponentsFromIndex()方法，它会从spring.components中获取满足条件的全限定类名，
然后读取对应类文件，最后构建成BeanDefinition对象：
private Set<BeanDefinition> addCandidateComponentsFromIndex(CandidateComponentsIndex index, String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
// 根据includeFilters中的条件和basePackage从spring.components中获取对应类
Set<String> types = new HashSet<>();
for (TypeFilter filter : this.includeFilters) {
// stereotype是注解全限定类名，如org.springframework.stereotype.Component
String stereotype = extractStereotype(filter);
if (stereotype == null) {
throw new IllegalArgumentException("Failed to extract stereotype from " + filter);
}
// 根据basePackage和stereotype，从spring.components中获取对应类
types.addAll(index.getCandidateTypes(basePackage, stereotype));
}
// 遍历所有类
for (String type : types) {
// 获取元数据
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(type);
// 校验是否满足excludeFilters和includeFilters条件（注意校验顺序）
if (isCandidateComponent(metadataReader)) {
// 解析成BeanDefinition，设置基本属性
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setSource(metadataReader.getResource());
// 校验BeanDefinition是否满足条件：比如是否可以进行初始化
if (isCandidateComponent(sbd)) {
candidates.add(sbd);
}
}
}
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("I/O failure during classpath scanning", ex);
}
return candidates;
}
CandidateComponentsIndex#getCandidateTypes()方法定义了从spring.components扫描的逻辑：
public Set<String> getCandidateTypes(String basePackage, String stereotype) {
// 获取符合注解条件的所有候补类
List<Entry> candidates = this.index.get(stereotype);
if (candidates != null) {
// 过滤出满足包条件的所有类
return candidates.parallelStream()
.filter(t -> t.match(basePackage))
.map(t -> t.type)
.collect(Collectors.toSet());
}
return Collections.emptySet();
}
SimpleMetadataReaderFactory#getMetadataReader()会使用resourceLoader读取类文件, 然后解析类文件的注解信息：
public MetadataReader getMetadataReader(String className) throws IOException {
try {
// 类文件路径：classpath:全限定类名.class
String resourcePath = ResourceLoader.CLASSPATH_URL_PREFIX +
ClassUtils.convertClassNameToResourcePath(className) + ClassUtils.CLASS_FILE_SUFFIX;
// 获取类文件的ClassPathResource对象
Resource resource = this.resourceLoader.getResource(resourcePath);
// 读取元数据
return getMetadataReader(resource);
}
catch (FileNotFoundException ex) {
}
}
SimpleMetadataReaderFactory#getMetadataReader()方法实际上会创建一个SimpleMetadataReader对象，在它的构造函数中会解析注解元数据。解析过程会使用
ASM操作Java字节码，这里不进行过多介绍（还没研究过），这里使用了访问者模式：
SimpleMetadataReader(Resource resource, @Nullable ClassLoader classLoader) throws IOException {
SimpleAnnotationMetadataReadingVisitor visitor = new SimpleAnnotationMetadataReadingVisitor(classLoader);
// 解析注解元数据：调用ClassReader#accept()方法
getClassReader(resource).accept(visitor, PARSING_OPTIONS);
this.resource = resource;
this.annotationMetadata = visitor.getMetadata();
}
回到ClassPathScanningCandidateComponentProvider#addCandidateComponentsFromIndex()方法，接下来会调用
ClassPathScanningCandidateComponentProvider#isCandidateComponent()方法进行过滤：
1. 按excludeFilters条件过滤（默认是空）。
2. 按includeFilters条件过滤（默认是@Component）。
3. 按@Conditional条件过滤。
ClassPathScanningCandidateComponentProvider#isCandidateComponent()方法如下：
protected boolean isCandidateComponent(MetadataReader metadataReader) throws IOException {
// 按excludeFilters条件过滤（默认是空）
for (TypeFilter tf : this.excludeFilters) {
if (tf.match(metadataReader, getMetadataReaderFactory())) {
return false;
}
}
// 按includeFilters条件过滤（默认是@Component）
for (TypeFilter tf : this.includeFilters) {
if (tf.match(metadataReader, getMetadataReaderFactory())) {
// 按@Conditional条件过滤
return isConditionMatch(metadataReader);
}
}
return false;
}
4.2.4、扫描类路径
ClassPathScanningCandidateComponentProvider#scanCandidateComponents()方法会扫描类路径下所有满足条件的类。它的操作与扫描spring.components配置一致，只是类文件
来源不同：
private Set<BeanDefinition> scanCandidateComponents(String basePackage) {
Set<BeanDefinition> candidates = new LinkedHashSet<>();
try {
// 类文件路径匹配规则：classpath*:包路径/**/*.class
String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +
resolveBasePackage(basePackage) + '/' + this.resourcePattern;
// 加载包路径下所有类文件
Resource[] resources = getResourcePatternResolver().getResources(packageSearchPath);
// 遍历所有类文件
for (Resource resource : resources) {
try {
// 读取元数据
MetadataReader metadataReader = getMetadataReaderFactory().getMetadataReader(resource);
// 校验是否满足excludeFilters和includeFilters条件（注意校验顺序）
if (isCandidateComponent(metadataReader)) {
// 解析成BeanDefinition，设置基本属性
ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);
sbd.setSource(resource);
// 校验BeanDefinition是否满足条件：比如是否可以进行初始化
if (isCandidateComponent(sbd)) {
candidates.add(sbd);
}
}
}
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;
}
4.3.1、注册BeanDefinition
回到ClassPathBeanDefinitionScanner#doScan()方法，此时我们已经得到了BeanDefinition对象。接下来会进行设置作用域、beanName等基本属性。
4.3.2、registerAnnotationConfigProcessors
回到ClassPathBeanDefinitionScanner#scan()方法，在扫描并注册完指定路径下的类后，还会注册XxxProcessor：
// 默认为true
if (this.includeAnnotationConfig) {
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
在AnnotationConfigUtils#registerAnnotationConfigProcessors()方法中，会添加许多后处理器：
* ConfigurationClassPostProcessor：处理@Configuration。
* AutowiredAnnotationBeanPostProcessor：处理@Autowired和@Value。
* CommonAnnotationBeanPostProcessor：提供对JSR-250的支持。
* internalPersistenceAnnotationProcessor：提供对JPA的支持。
* EventListenerMethodProcessor和DefaultEventListenerFactory：处理@EventListener
AnnotationConfigUtils#registerAnnotationConfigProcessors()方法如下：
public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
BeanDefinitionRegistry registry, @Nullable Object source) {
DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
if (beanFactory != null) {
// 添加对@Order的支持
if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) {
beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);
}
// 添加对@Qualifier和@Value的支持
if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) {
beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
}
}
Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);
// 添加ConfigurationClassPostProcessor后处理器：@Configuration
if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 添加AutowiredAnnotationBeanPostProcessor后处理器：@Autowired和@Value
if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 添加CommonAnnotationBeanPostProcessor后处理器：@PostConstruct、@PreDestroy、@Resource等
if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 添加PersistenceAnnotationBeanPostProcessor后处理器：支持JPA功能
if (jpaPresent && !registry.containsBeanDefinition(PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition();
try {
def.setBeanClass(ClassUtils.forName(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME,
AnnotationConfigUtils.class.getClassLoader()));
}
catch (ClassNotFoundException ex) {
throw new IllegalStateException(
"Cannot load optional framework class: " + PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, ex);
}
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// 添加EventListenerMethodProcessor后处理器：@EventListener
if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME));
}
// 添加DefaultEventListenerFactory后处理器：@EventListener
if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) {
RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME));
}
return beanDefs;
}
5、在 Spring 内部的使用
5.1、AnnotationConfigApplicationContext: 在使用AnnotationConfigApplicationContext时，它内部会调用ClassPathBeanDefinitionScanner成员变量进行注册bean。
5.2、@ComponentScan
@ComponentScan底层会调用ClassPathBeanDefinitionScanner进行注册bean，ComponentScanAnnotationParser#parse()：
public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, String declaringClass) {
ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry,
componentScan.getBoolean("useDefaultFilters"), this.environment, this.resourceLoader);
Class<? extends BeanNameGenerator> generatorClass = componentScan.getClass("nameGenerator");
boolean useInheritedGenerator = (BeanNameGenerator.class == generatorClass);
scanner.setBeanNameGenerator(useInheritedGenerator ? this.beanNameGenerator :
BeanUtils.instantiateClass(generatorClass));
ScopedProxyMode scopedProxyMode = componentScan.getEnum("scopedProxy");
if (scopedProxyMode != ScopedProxyMode.DEFAULT) {
scanner.setScopedProxyMode(scopedProxyMode);
}
else {
Class<? extends ScopeMetadataResolver> resolverClass = componentScan.getClass("scopeResolver");
scanner.setScopeMetadataResolver(BeanUtils.instantiateClass(resolverClass));
}
scanner.setResourcePattern(componentScan.getString("resourcePattern"));
for (AnnotationAttributes includeFilterAttributes : componentScan.getAnnotationArray("includeFilters")) {
List<TypeFilter> typeFilters = TypeFilterUtils.createTypeFiltersFor(includeFilterAttributes, this.environment,
this.resourceLoader, this.registry);
for (TypeFilter typeFilter : typeFilters) {
scanner.addIncludeFilter(typeFilter);
}
}
for (AnnotationAttributes excludeFilterAttributes : componentScan.getAnnotationArray("excludeFilters")) {
List<TypeFilter> typeFilters = TypeFilterUtils.createTypeFiltersFor(excludeFilterAttributes, this.environment,
this.resourceLoader, this.registry);
for (TypeFilter typeFilter : typeFilters) {
scanner.addExcludeFilter(typeFilter);
}
}
boolean lazyInit = componentScan.getBoolean("lazyInit");
if (lazyInit) {
scanner.getBeanDefinitionDefaults().setLazyInit(true);
}
Set<String> basePackages = new LinkedHashSet<>();
String[] basePackagesArray = componentScan.getStringArray("basePackages");
for (String pkg : basePackagesArray) {
String[] tokenized = StringUtils.tokenizeToStringArray(this.environment.resolvePlaceholders(pkg),
ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS);
Collections.addAll(basePackages, tokenized);
}
for (Class<?> clazz : componentScan.getClassArray("basePackageClasses")) {
basePackages.add(ClassUtils.getPackageName(clazz));
}
if (basePackages.isEmpty()) {
basePackages.add(ClassUtils.getPackageName(declaringClass));
}
scanner.addExcludeFilter(new AbstractTypeHierarchyTraversingFilter(false, false) {
@Override
protected boolean matchClassName(String className) {
return declaringClass.equals(className);
}
});
return scanner.doScan(StringUtils.toStringArray(basePackages));
}
5.3、 Mybatis的ClassPathMapperScanner继承了ClassPathBeanDefinitionScanner，@MapperScan使用它来注册bean。
org.mybatis.spring.mapper.MapperScannerConfigurer#postProcessBeanDefinitionRegistry()：
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
if (this.processPropertyPlaceHolders) {
processPropertyPlaceHolders();
}
ClassPathMapperScanner scanner = new ClassPathMapperScanner(registry);
scanner.setAddToConfig(this.addToConfig);
scanner.setAnnotationClass(this.annotationClass);
scanner.setMarkerInterface(this.markerInterface);
scanner.setSqlSessionFactory(this.sqlSessionFactory);
scanner.setSqlSessionTemplate(this.sqlSessionTemplate);
scanner.setSqlSessionFactoryBeanName(this.sqlSessionFactoryBeanName);
scanner.setSqlSessionTemplateBeanName(this.sqlSessionTemplateBeanName);
scanner.setResourceLoader(this.applicationContext);
scanner.setBeanNameGenerator(this.nameGenerator);
scanner.setMapperFactoryBeanClass(this.mapperFactoryBeanClass);
if (StringUtils.hasText(lazyInitialization)) {
scanner.setLazyInitialization(Boolean.valueOf(lazyInitialization));
}
if (StringUtils.hasText(defaultScope)) {
scanner.setDefaultScope(defaultScope);
}
scanner.registerFilters();
scanner.scan(
StringUtils.tokenizeToStringArray(this.basePackage, ConfigurableApplicationContext.CONFIG_LOCATION_DELIMITERS));
}
浙公网安备 33010602011771号