Spring IOC容器启动阶段.
SpringApplication.run方法. createApplicationContext()阶段, 依据WebType创建了AnnotationConfigServletWebServerApplicationContext类. 同时初始化了两个读取器.
- AnnotatedBeanDefinitionReader. 基于注解
- ClassPathBeanDefinitionScanner. 基于XML的
AnnotatedBeanDefinitionReader的构造器
<!– more –>
public AnnotatedBeanDefinitionReader(BeanDefinitionRegistry registry, Environment environment) {
Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
Assert.notNull(environment, "Environment must not be null");
this.registry = registry;
this.conditionEvaluator = new ConditionEvaluator(registry, environment, null);
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
// 在创建ApplicationContext的时候, 会注册几个BeanFactoryPostProcessor
public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
BeanDefinitionRegistry registry, @Nullable Object source) {
//获取BeanFactory. DefaultListableBeanFactory本身就是BeanDefinitionRegistry的实现类. 所以可以注册
DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
if (beanFactory != null) {
if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) {
beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);
}
if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) {
beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
}
}
Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);
if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
//注册自动装配的核心类 优先级为LOWEST_PRECEDENCE
RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
}
if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
//注册Autowire注解的核心类 优先级为LOWEST_PRECEDENCE-2
RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// Check for JSR-250 support, and if present add the CommonAnnotationBeanPostProcessor.
if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
//@PostConstruct @PreDestroy @Resource @WebServiceRef @WebServiceClient 的核心类 优先级为LOWEST_PRECEDENCE-3
RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
def.setSource(source);
beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
}
// Check for JPA support, and if present add the PersistenceAnnotationBeanPostProcessor.
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));
}
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));
}
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;
}由此我们知道了他们的执行顺序 CommonAnnotationBeanPostProcessor->AutowiredAnnotationBeanPostProcessor->AnnotationAwareOrderComparator
在run方法的时候 我们将启动类传入. 作为primarySources. 它的加载好和注册在prepareContext()阶段load()方法
protected void load(ApplicationContext context, Object[] sources) {
if (logger.isDebugEnabled()) {
logger.debug("Loading source " + StringUtils.arrayToCommaDelimitedString(sources));
}
//这里的注册器 依旧是DefaultListableBeanFactory.
BeanDefinitionLoader loader = createBeanDefinitionLoader(getBeanDefinitionRegistry(context), sources);
if (this.beanNameGenerator != null) {
loader.setBeanNameGenerator(this.beanNameGenerator);
}
if (this.resourceLoader != null) {
loader.setResourceLoader(this.resourceLoader);
}
if (this.environment != null) {
loader.setEnvironment(this.environment);
}
loader.load();
}
public int load() {
int count = 0;
for (Object source : this.sources) {
count += load(source);
}
return count;
}
private int load(Object source) {
Assert.notNull(source, "Source must not be null");
if (source instanceof Class<?>) {
return load((Class<?>) source);
}
if (source instanceof Resource) {
return load((Resource) source);
}
if (source instanceof Package) {
return load((Package) source);
}
if (source instanceof CharSequence) {
return load((CharSequence) source);
}
throw new IllegalArgumentException("Invalid source type " + source.getClass());
}
private int load(Class<?> source) {
if (isGroovyPresent() && GroovyBeanDefinitionSource.class.isAssignableFrom(source)) {
// Any GroovyLoaders added in beans{} DSL can contribute beans here
GroovyBeanDefinitionSource loader = BeanUtils.instantiateClass(source, GroovyBeanDefinitionSource.class);
load(loader);
}
if (isComponent(source)) {
// 在这里注册. AnnotatedGenericBeanDefinition
this.annotatedReader.register(source);
return 1;
}
return 0;
}ConfigurationClassPostProcessor的执行
ConfigurationClassPostProcessor这个的执行节点 就不介绍了. 具体逻辑在AbstractApplicationContext#refresh()invokeBeanFactoryPostProcessors()方法里.
ConfigurationClassPostProcessor是BeanDefinitionRegistryPostProcessor和PriorityOrdered的实现类. 所以会很快执行.
@Override
public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
int registryId = System.identityHashCode(registry);
if (this.registriesPostProcessed.contains(registryId)) {
throw new IllegalStateException(
"postProcessBeanDefinitionRegistry already called on this post-processor against " + registry);
}
if (this.factoriesPostProcessed.contains(registryId)) {
throw new IllegalStateException(
"postProcessBeanFactory already called on this post-processor against " + registry);
}
this.registriesPostProcessed.add(registryId);
//以上是为了 不能执行第二次
processConfigBeanDefinitions(registry);
}
public void processConfigBeanDefinitions(BeanDefinitionRegistry registry) {
List<BeanDefinitionHolder> configCandidates = new ArrayList<>();
//获取注册表中注册的类名.
String[] candidateNames = registry.getBeanDefinitionNames();
for (String beanName : candidateNames) {
//获得BeanDefinition
BeanDefinition beanDef = registry.getBeanDefinition(beanName);
// 防止重复执行
if (ConfigurationClassUtils.isFullConfigurationClass(beanDef) ||
ConfigurationClassUtils.isLiteConfigurationClass(beanDef)) {
if (logger.isDebugEnabled()) {
logger.debug("Bean definition has already been processed as a configuration class: " + beanDef);
}
}
//必须是@Configuration或者@Bean注解的 满足条件的只有一个 Spring的入口类
else if (ConfigurationClassUtils.checkConfigurationClassCandidate(beanDef, this.metadataReaderFactory)) {
configCandidates.add(new BeanDefinitionHolder(beanDef, beanName));
}
}
// Return immediately if no @Configuration classes were found
//到这里 就
if (configCandidates.isEmpty()) {
return;
}
// Sort by previously determined @Order value, if applicable
// 排序
configCandidates.sort((bd1, bd2) -> {
int i1 = ConfigurationClassUtils.getOrder(bd1.getBeanDefinition());
int i2 = ConfigurationClassUtils.getOrder(bd2.getBeanDefinition());
return Integer.compare(i1, i2);
});
// Detect any custom bean name generation strategy supplied through the enclosing application context
SingletonBeanRegistry sbr = null;
if (registry instanceof SingletonBeanRegistry) {
sbr = (SingletonBeanRegistry) registry;
if (!this.localBeanNameGeneratorSet) {
BeanNameGenerator generator = (BeanNameGenerator) sbr.getSingleton(CONFIGURATION_BEAN_NAME_GENERATOR);
if (generator != null) {
this.componentScanBeanNameGenerator = generator;
this.importBeanNameGenerator = generator;
}
}
}
if (this.environment == null) {
this.environment = new StandardEnvironment();
}
// Parse each @Configuration class
//@Configuration注解的解析器
//registry是org.springframework.beans.factory.support.DefaultListableBeanFactory
//resourceLoader是org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext
//componentScanBeanNameGenerator是 AnnotationBeanNameGenerator. 给bean取名字的
//这个构造器里会new ComponentScanAnnotationParser(environment, resourceLoader, componentScanBeanNameGenerator, registry); 看名字就可以直到这是 @ComponentScan的解析器
ConfigurationClassParser parser = new ConfigurationClassParser(
this.metadataReaderFactory, this.problemReporter, this.environment,
this.resourceLoader, this.componentScanBeanNameGenerator, registry);
Set<BeanDefinitionHolder> candidates = new LinkedHashSet<>(configCandidates);
Set<ConfigurationClass> alreadyParsed = new HashSet<>(configCandidates.size());
// 循环pase. 以为在parse的时候 也会伴随新的BeanDefinition的注册. 这些新注册的可能也是需要parse的
do {
parser.parse(candidates);
parser.validate();
// 当执行解析之后 这里获得了所有的解析完成的集合
Set<ConfigurationClass> configClasses = new LinkedHashSet<>(parser.getConfigurationClasses());
configClasses.removeAll(alreadyParsed);
// Read the model and create bean definitions based on its content
if (this.reader == null) {
this.reader = new ConfigurationClassBeanDefinitionReader(
registry, this.sourceExtractor, this.resourceLoader, this.environment,
this.importBeanNameGenerator, parser.getImportRegistry());
}
//通过阅读器注册到BeanFactory中() 例外是@ImportResource注解 他会调用响应的阅读器. 继续注入到beanFactory
this.reader.loadBeanDefinitions(configClasses);
// 标记已经解析完成的
alreadyParsed.addAll(configClasses);
// 解析候选列表清除
candidates.clear();
// 如果注册标的数量 大于 刚开始解析之前的数量 说明是解析Configuration类的时候有注册的 所以要继续parse
if (registry.getBeanDefinitionCount() > candidateNames.length) {
// BeanFactory中所有的
String[] newCandidateNames = registry.getBeanDefinitionNames();
// 老的
Set<String> oldCandidateNames = new HashSet<>(Arrays.asList(candidateNames));
//已经parse的
Set<String> alreadyParsedClasses = new HashSet<>();
for (ConfigurationClass configurationClass : alreadyParsed) {
// 合并alreadyParsed和alreadyParsedClasses
alreadyParsedClasses.add(configurationClass.getMetadata().getClassName());
}
for (String candidateName : newCandidateNames) {
// 老的中不包含
if (!oldCandidateNames.contains(candidateName)) {
BeanDefinition bd = registry.getBeanDefinition(candidateName);
// 已经parse的要排除掉
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bd, this.metadataReaderFactory) &&
!alreadyParsedClasses.contains(bd.getBeanClassName())) {
// 这里添加的就是 parse阶段新添加的.
candidates.add(new BeanDefinitionHolder(bd, candidateName));
}
}
}
candidateNames = newCandidateNames;
}
}
// 继续parse
while (!candidates.isEmpty());
// Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
if (sbr != null && !sbr.containsSingleton(IMPORT_REGISTRY_BEAN_NAME)) {
sbr.registerSingleton(IMPORT_REGISTRY_BEAN_NAME, parser.getImportRegistry());
}
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();
}
}ConfigurationClassParser#parse(candidates) candidates(spring项目的入口类)也就是@SpringBootApplication标记了这个注解的类
//构造器
public ConfigurationClassParser(MetadataReaderFactory metadataReaderFactory,
ProblemReporter problemReporter, Environment environment, ResourceLoader resourceLoader,
BeanNameGenerator componentScanBeanNameGenerator, BeanDefinitionRegistry registry) {
this.metadataReaderFactory = metadataReaderFactory;
this.problemReporter = problemReporter;
this.environment = environment;
this.resourceLoader = resourceLoader;
this.registry = registry;
//这里
this.componentScanParser = new ComponentScanAnnotationParser(
environment, resourceLoader, componentScanBeanNameGenerator, registry);
// 这里
this.conditionEvaluator = new ConditionEvaluator(registry, environment, resourceLoader);
}
public void parse(Set<BeanDefinitionHolder> configCandidates) {
for (BeanDefinitionHolder holder : configCandidates) {
BeanDefinition bd = holder.getBeanDefinition();
try {
if (bd instanceof AnnotatedBeanDefinition) {
parse(((AnnotatedBeanDefinition) bd).getMetadata(), holder.getBeanName());
}
else if (bd instanceof AbstractBeanDefinition && ((AbstractBeanDefinition) bd).hasBeanClass()) {
parse(((AbstractBeanDefinition) bd).getBeanClass(), holder.getBeanName());
}
else {
parse(bd.getBeanClassName(), holder.getBeanName());
}
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to parse configuration class [" + bd.getBeanClassName() + "]", ex);
}
}
// 延迟执行的 这里执行了
this.deferredImportSelectorHandler.process();
}
protected final void parse(@Nullable String className, String beanName) throws IOException {
Assert.notNull(className, "No bean class name for configuration class bean definition");
MetadataReader reader = this.metadataReaderFactory.getMetadataReader(className);
processConfigurationClass(new ConfigurationClass(reader, beanName));
}
protected final void parse(Class<?> clazz, String beanName) throws IOException {
processConfigurationClass(new ConfigurationClass(clazz, beanName));
}
protected final void parse(AnnotationMetadata metadata, String beanName) throws IOException {
processConfigurationClass(new ConfigurationClass(metadata, beanName));
}
protected void processConfigurationClass(ConfigurationClass configClass) throws IOException {
if (this.conditionEvaluator.shouldSkip(configClass.getMetadata(), ConfigurationPhase.PARSE_CONFIGURATION)) {
return;
}
ConfigurationClass existingClass = this.configurationClasses.get(configClass);
if (existingClass != null) {
if (configClass.isImported()) {
if (existingClass.isImported()) {
existingClass.mergeImportedBy(configClass);
}
// Otherwise ignore new imported config class; existing non-imported class overrides it.
return;
}
else {
// Explicit bean definition found, probably replacing an import.
// Let's remove the old one and go with the new one.
this.configurationClasses.remove(configClass);
this.knownSuperclasses.values().removeIf(configClass::equals);
}
}
// Recursively process the configuration class and its superclass hierarchy.
SourceClass sourceClass = asSourceClass(configClass);
do {
sourceClass = doProcessConfigurationClass(configClass, sourceClass);
}
while (sourceClass != null);
// 每当解析完成以后 就添加到这集合中ConfigurationClassParser的configurationClasses集合
this.configurationClasses.put(configClass, configClass);
}
@Nullable
protected final SourceClass doProcessConfigurationClass(ConfigurationClass configClass, SourceClass sourceClass)
throws IOException {
// 优先解析标记了@Component注解的类 解析例如在@Controller里写的@Bean或者@Configuration 嵌套的情况. 在入口类中写了一些逻辑的情况
if (configClass.getMetadata().isAnnotated(Component.class.getName())) {
// Recursively process any member (nested) classes first
processMemberClasses(configClass, sourceClass);
}
// Process any @PropertySource annotations
//解析@PropertySource注解 例如这种情况
// @Configuration
//@PropertySource("classpath:/com/myco/a.properties")
//public class ConfigA { }
//
for (AnnotationAttributes propertySource : AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), PropertySources.class,
org.springframework.context.annotation.PropertySource.class)) {
if (this.environment instanceof ConfigurableEnvironment) {
processPropertySource(propertySource);
}
else {
logger.info("Ignoring @PropertySource annotation on [" + sourceClass.getMetadata().getClassName() +
"]. Reason: Environment must implement ConfigurableEnvironment");
}
}
// Process any @ComponentScan annotations
//sourceClass.getMetadata()上的@ComponentScan注解的解析 兼容ComponentScans的形式
Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(
sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
if (!componentScans.isEmpty() &&
!this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
//遍历一个一个解析
for (AnnotationAttributes componentScan : componentScans) {
// The config class is annotated with @ComponentScan -> perform the scan immediately
//case 1
Set<BeanDefinitionHolder> scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
// Check the set of scanned definitions for any further config classes and parse recursively if needed
// 拿到了ComponentScan指定扫描包中所有的元注解为@Component的类
for (BeanDefinitionHolder holder : scannedBeanDefinitions) {
BeanDefinition bdCand = holder.getBeanDefinition().getOriginatingBeanDefinition();
if (bdCand == null) {
bdCand = holder.getBeanDefinition();
}
if (ConfigurationClassUtils.checkConfigurationClassCandidate(bdCand, this.metadataReaderFactory)) {
// 继续解析 这些类中 @Configuration和@Bean的类
parse(bdCand.getBeanClassName(), holder.getBeanName());
}
}
}
}
// Process any @Import annotations
// getImports(sourceClass) 这个方法是获取@Import注解导入的类, 平铺开 以@SpringBootApplication注解为例子 返回的Set<SourceClass>集合中包含
//AutoConfigurationImportSelector.class和AutoConfigurationPackages.Registrar.class
// processImports case 3
processImports(configClass, sourceClass, getImports(sourceClass), true);
// Process any @ImportResource annotations
// @ImportResource注解的解析. 并将解析的类注册到ConfigurationClass类的importedResources map中
AnnotationAttributes importResource =
AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ImportResource.class);
if (importResource != null) {
String[] resources = importResource.getStringArray("locations");
Class<? extends BeanDefinitionReader> readerClass = importResource.getClass("reader");
for (String resource : resources) {
String resolvedResource = this.environment.resolveRequiredPlaceholders(resource);
configClass.addImportedResource(resolvedResource, readerClass);
}
}
// Process individual @Bean methods
// @Bean注解的解析 注册ConfigurationClass类的beanMethods SET中
Set<MethodMetadata> beanMethods = retrieveBeanMethodMetadata(sourceClass);
for (MethodMetadata methodMetadata : beanMethods) {
configClass.addBeanMethod(new BeanMethod(methodMetadata, configClass));
}
// Process default methods on interfaces
processInterfaces(configClass, sourceClass);
// Process superclass, if any
if (sourceClass.getMetadata().hasSuperClass()) {
String superclass = sourceClass.getMetadata().getSuperClassName();
if (superclass != null && !superclass.startsWith("java") &&
!this.knownSuperclasses.containsKey(superclass)) {
this.knownSuperclasses.put(superclass, configClass);
// Superclass found, return its annotation metadata and recurse
return sourceClass.getSuperClass();
}
}
// No superclass -> processing is complete
return null;
}ConfigurationClassParser#parse(candidates)内部执行的方法就是doProcessConfigurationClass()
case:1 ComponentScanAnnotationParser#parse()方法
public Set<BeanDefinitionHolder> parse(AnnotationAttributes componentScan, final String declaringClass) {
//case 2
// 这个扫描器很熟悉了 componentScan.getBoolean("useDefaultFilters") = true
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 filter : componentScan.getAnnotationArray("includeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
scanner.addIncludeFilter(typeFilter);
}
}
for (AnnotationAttributes filter : componentScan.getAnnotationArray("excludeFilters")) {
for (TypeFilter typeFilter : typeFiltersFor(filter)) {
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));
}
//basePackages和basePackageClasses的解析是去并集的.
// basePackages和basePackageClasses都设置过. 那么就用declaringClass的包目录.
//declaringClass这个类就是我们spring的入口类, 可以理解为入口类放在哪个包. 扫描哪个包下的所有类.
if (basePackages.isEmpty()) {
basePackages.add(ClassUtils.getPackageName(declaringClass));
}
scanner.addExcludeFilter(new AbstractTypeHierarchyTraversingFilter(false, false) {
@Override
protected boolean matchClassName(String className) {
return declaringClass.equals(className);
}
});
//扫描逻辑. 因为是注解驱动的. 所以扫描basePackages包下所有元注解为@Component的.
// 元注解的意思就是 注解上的注解. 我们熟知的Controller的元注解就是@Component. 自己去看吧
// 读取类信息是通过ASM做的. ASM我是实在看不懂了.
return scanner.doScan(StringUtils.toStringArray(basePackages));
}ClassPathBeanDefinitionScanner类
ClassPathBeanDefinitionScanner#doScan 在扫描时 是扫描所有的basePackages下所有的.Class文件. 不要那些类和留下那些类. 是通过过滤器实现的
includeFilters是留下类的过滤器
- new AnnotationTypeFilter(Component.class)
- new AnnotationTypeFilter(((Class<? extends Annotation>) ClassUtils.forName(“javax.annotation.ManagedBean”, cl)), false)
- new AnnotationTypeFilter(((Class<? extends Annotation>) ClassUtils.forName(“javax.inject.Named”, cl)), false)
excludeFilters是不要类过滤器: 是componentScan指定的 “@ComponentScan(excludeFilters = { @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
@Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })``
TypeExcludeFilter和AutoConfigurationExcludeFilter过滤器. 大体是 @Configuration MATE-INF/spring.factories文件中EnableAutoConfiguration类型的类 排除
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);
}
// ClassPathScanningCandidateComponentProvider是ClassPathBeanDefinitionScanner父类 包含的过滤器. 留下的类
@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("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.
}
}经过扫描 最后留下的类基本就这
- {@link Component @Component}, {@link Repository @Repository},
- {@link Service @Service}, and {@link Controller @Controller}
processImports(configClass, sourceClass, getImports(sourceClass), true)
以入口类为例子:
configClass和sourceClass值都是 spring的入口类
importCandidates指的是 入口类上@import()注解导入类的集合
checkForCircularImports 检查循环导入
- 先执行注册延迟导入相关DeferredImportSelector
- 再执行ImportSelector#selectImports 返回是一些类的名字. 继续processImports() 这种方式是 导入其他自动装配类的时候使用的
- ImportBeanDefinitionRegistrar 注册实现了ImportBeanDefinitionRegistrar接口的类到 importBeanDefinitionRegistrars到Map 注意这里并没有执行
- 以上情况都不是 就执行@Configuration标注的类本身 最终状态. 解析@Bean的情况
private void processImports(ConfigurationClass configClass, SourceClass currentSourceClass,
Collection<SourceClass> importCandidates, boolean checkForCircularImports) {
if (importCandidates.isEmpty()) {
return;
}
if (checkForCircularImports && isChainedImportOnStack(configClass)) {
this.problemReporter.error(new CircularImportProblem(configClass, this.importStack));
}
else {
//解决循环导入的
this.importStack.push(configClass);
try {
for (SourceClass candidate : importCandidates) {
if (candidate.isAssignable(ImportSelector.class)) {
// Candidate class is an ImportSelector -> delegate to it to determine imports
Class<?> candidateClass = candidate.loadClass();
ImportSelector selector = BeanUtils.instantiateClass(candidateClass, ImportSelector.class);
ParserStrategyUtils.invokeAwareMethods(
selector, this.environment, this.resourceLoader, this.registry);
if (selector instanceof DeferredImportSelector) {
this.deferredImportSelectorHandler.handle(configClass, (DeferredImportSelector) selector);
}
else {
String[] importClassNames = selector.selectImports(currentSourceClass.getMetadata());
Collection<SourceClass> importSourceClasses = asSourceClasses(importClassNames);
processImports(configClass, currentSourceClass, importSourceClasses, false);
}
}
else if (candidate.isAssignable(ImportBeanDefinitionRegistrar.class)) {
// Candidate class is an ImportBeanDefinitionRegistrar ->
// delegate to it to register additional bean definitions
Class<?> candidateClass = candidate.loadClass();
//初始化
ImportBeanDefinitionRegistrar registrar =
BeanUtils.instantiateClass(candidateClass, ImportBeanDefinitionRegistrar.class);
// setAware
ParserStrategyUtils.invokeAwareMethods(
registrar, this.environment, this.resourceLoader, this.registry);
//注册
configClass.addImportBeanDefinitionRegistrar(registrar, currentSourceClass.getMetadata());
}
else {
// Candidate class not an ImportSelector or ImportBeanDefinitionRegistrar ->
// process it as an @Configuration class
this.importStack.registerImport(
currentSourceClass.getMetadata(), candidate.getMetadata().getClassName());
processConfigurationClass(candidate.asConfigClass(configClass));
}
}
}
catch (BeanDefinitionStoreException ex) {
throw ex;
}
catch (Throwable ex) {
throw new BeanDefinitionStoreException(
"Failed to process import candidates for configuration class [" +
configClass.getMetadata().getClassName() + "]", ex);
}
finally {
this.importStack.pop();
}
}
}
