public class AnnotationConfigApplicationContext extends GenericApplicationContext {//创建一个读取注解的Bean定义读取器，并将其设置到容器中private final AnnotatedBeanDefinitionReader reader = new AnnotatedBeanDefinitionReader(this);//创建一个扫描指定类路径中注解Bean定义的扫描器，并将其设置到容器中private final ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this);
//默认构造函数，初始化一个空容器，容器不包含任何 Bean 信息，需要在稍后通过调用其register() //方法注册配置类，并调用refresh()方法刷新容器，触发容器对注解Bean的载入、解析和注册过程public AnnotationConfigApplicationContext() {}//最常用的构造函数，通过将涉及到的配置类传递给该构造函数，以实现将相应配置类中的Bean
//自动注册到容器中public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {register(annotatedClasses);refresh();}
//该构造函数会自动扫描以给定的包及其子包下的所有类，并自动识别所有的Spring Bean，将其
//注册到容器中public AnnotationConfigApplicationContext(String... basePackages) {scan(basePackages);refresh();}//为容器的注解Bean读取器和注解Bean扫描器设置Bean名称产生器public void setBeanNameGenerator(BeanNameGenerator beanNameGenerator) {this.reader.setBeanNameGenerator(beanNameGenerator);this.scanner.setBeanNameGenerator(beanNameGenerator);}//为容器的注解Bean读取器和注解Bean扫描器设置作用范围元信息解析器public void setScopeMetadataResolver(ScopeMetadataResolver scopeMetadataResolver) {this.reader.setScopeMetadataResolver(scopeMetadataResolver);this.scanner.setScopeMetadataResolver(scopeMetadataResolver);}//为容器注册一个要被处理的注解Bean，新注册的Bean，必须手动调用容器的
//refresh()方法刷新容器，触发容器对新注册的Bean的处理public void register(Class<?>... annotatedClasses) {this.reader.register(annotatedClasses);}//扫描指定包路径及其子包下的注解类，为了使新添加的类被处理，必须手动调用//refresh()方法刷新容器public void scan(String... basePackages) {this.scanner.scan(basePackages);}
}

//注册多个注解Bean定义类
public void register(Class<?>... annotatedClasses) {for (Class<?> annotatedClass : annotatedClasses) {registerBean(annotatedClass);}}//注册一个注解Bean定义类public void registerBean(Class<?> annotatedClass) {registerBean(annotatedClass, null, (Class<? extends Annotation>[]) null);}//Bean定义读取器注册注解Bean定义的入口方法public void registerBean(Class<?> annotatedClass, Class<? extends Annotation>... qualifiers) {registerBean(annotatedClass, null, qualifiers);}//Bean定义读取器向容器注册注解Bean定义类public void registerBean(Class<?> annotatedClass, String name, Class<? extends Annotation>... qualifiers) {//根据指定的注解Bean定义类，创建Spring容器中对注解Bean的封装的数据结构AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);//解析注解Bean定义的作用域，若@Scope("prototype")，则Bean为原型类型；//若@Scope("singleton")，则Bean为单态类型ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);//为注解Bean定义设置作用域abd.setScope(scopeMetadata.getScopeName());//为注解Bean定义生成Bean名称String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));//处理注解Bean定义中的通用注解AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);//如果在向容器注册注解Bean定义时，使用了额外的限定符注解，则解析限定符注解。//主要是配置的关于autowiring自动依赖注入装配的限定条件，即@Qualifier
//注解，Spring自动依赖注入装配默认是按类型装配，如果使用@Qualifier则按名称if (qualifiers != null) {for (Class<? extends Annotation> qualifier : qualifiers) {
//如果配置了@Primary注解，设置该Bean为autowiring自动依赖注入装//配时的首选if (Primary.class.equals(qualifier)) {abd.setPrimary(true);}//如果配置了@Lazy注解，则设置该Bean为非延迟初始化，如果没有配置，//则该Bean为预实例化else if (Lazy.class.equals(qualifier)) {abd.setLazyInit(true);}//如果使用了除@Primary和@Lazy以外的其他注解，则为该Bean添加一
//个autowiring自动依赖注入装配限定符，该Bean在进autowiring
//自动依赖注入装配时，根据名称装配限定符指定的Beanelse {abd.addQualifier(new AutowireCandidateQualifier(qualifier));}}}//创建一个指定Bean名称的Bean定义对象，封装注解Bean定义类数据BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);//根据注解Bean定义类中配置的作用域，创建相应的代理对象definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);//向IoC容器注册注解Bean类定义对象  BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);}

//解析注解Bean定义类中的作用域元信息
public ScopeMetadata resolveScopeMetadata(BeanDefinition definition) {ScopeMetadata metadata = new ScopeMetadata();if (definition instanceof AnnotatedBeanDefinition) {AnnotatedBeanDefinition annDef = (AnnotatedBeanDefinition) definition;//从注解Bean定义类的属性中查找属性为”Scope”的值，即@Scope注解的值// annDef.getMetadata().getAnnotationAttributes方法将Bean
//中所有的注解和注解的值存放在一个map集合中Map<String, Object> attributes =annDef.getMetadata().getAnnotationAttributes(this.scopeAnnotationType.getName());//将获取到的@Scope注解的值设置到要返回的对象中if (attributes != null) {metadata.setScopeName((String) attributes.get("value"));//获取@Scope注解中的proxyMode属性值，在创建代理对象时会用到ScopedProxyMode proxyMode = (ScopedProxyMode) attributes.get("proxyMode");//如果@Scope的proxyMode属性值为null、DEFAULT或者NOif (proxyMode == null || proxyMode == ScopedProxyMode.DEFAULT) {//设置proxyMode为NOproxyMode = this.defaultProxyMode;}//为返回的元数据设置proxyModemetadata.setScopedProxyMode(proxyMode);}}//返回解析的作用域元信息对象return metadata;}

//根据作用域为Bean应用引用的代码模式
static BeanDefinitionHolder applyScopedProxyMode(ScopeMetadata metadata, BeanDefinitionHolder definition, BeanDefinitionRegistry registry) {//获取注解Bean定义类中@Scope注解的proxyMode属性值ScopedProxyMode scopedProxyMode = metadata.getScopedProxyMode();//如果配置的@Scope注解的proxyMode属性值为NO，则不应用代理模式if (scopedProxyMode.equals(ScopedProxyMode.NO)) {return definition;}
//获取配置的@Scope注解的proxyMode属性值，如果为TARGET_CLASS，则返
//回true，如果为INTERFACES，则返回falseboolean proxyTargetClass = scopedProxyMode.equals(ScopedProxyMode.TARGET_CLASS);//为注册的Bean创建相应模式的代理对象return ScopedProxyCreator.createScopedProxy(definition, registry, proxyTargetClass);}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface Component {String value() default "";
}

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Service {String value() default "";
}

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Controller {String value() default "";
}

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component
public @interface Repository {String value() default "";
}

public class ClassPathScanningCandidateComponentProvider implements ResourceLoaderAware {
//保存过滤规则要包含的注解，即Spring默认的@Component、@Repository、@Service、//@Controller注解的Bean，以及JavaEE6的@ManagedBean和JSR-330的@Named注解
private final List<TypeFilter> includeFilters = new LinkedList<TypeFilter>();
//保存过滤规则要排除的注解
private final List<TypeFilter> excludeFilters = new LinkedList<TypeFilter>();
//构造方法，该方法在子类ClassPathBeanDefinitionScanner的构造方法中被调用
public ClassPathScanningCandidateComponentProvider(boolean useDefaultFilters) {//如果使用Spring默认的过滤规则，则向容器注册过滤规则if (useDefaultFilters) {registerDefaultFilters();}}
//向容器注册过滤规则
protected void registerDefaultFilters() {
//向要包含的过滤规则中添加@Component注解类，注意Spring中@Repository
//@Service和@Controller都是Component，因为这些注解都添加了@Component注解this.includeFilters.add(new AnnotationTypeFilter(Component.class));//获取当前类的类加载器ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();try {//向要包含的过滤规则添加JavaEE6的@ManagedBean注解this.includeFilters.add(new AnnotationTypeFilter(((Class<? extends Annotation>) cl.loadClass("javax.annotation.ManagedBean")), false));logger.info("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 {//向要包含的过滤规则添加@Named注解this.includeFilters.add(new AnnotationTypeFilter(((Class<? extends Annotation>) cl.loadClass("javax.inject.Named")), false));logger.info("JSR-330 'javax.inject.Named' annotation found and supported for component scanning");}catch (ClassNotFoundException ex) {// JSR-330 API not available - simply skip.}}
//扫描给定类路径的包
public Set<BeanDefinition> findCandidateComponents(String basePackage) {//创建存储扫描到的类的集合Set<BeanDefinition> candidates = new LinkedHashSet<BeanDefinition>();try {//解析给定的包路径，this.resourcePattern=” **/*.class”，//ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX=“classpath:”//resolveBasePackage方法将包名中的”.”转换为文件系统的”/”String packageSearchPath = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX +resolveBasePackage(basePackage) + "/" + this.resourcePattern;//将给定的包路径解析为Spring资源对象Resource[] resources = this.resourcePatternResolver.getResources(packageSearchPath);boolean traceEnabled = logger.isTraceEnabled();boolean debugEnabled = logger.isDebugEnabled();//遍历扫描到的资源for (Resource resource : resources) {if (traceEnabled) {logger.trace("Scanning " + resource);}if (resource.isReadable()) {try {
//为指定资源获取元数据读取器，元信息读取器通过汇编(ASM)读//取资源元信息MetadataReader metadataReader = this.metadataReaderFactory.getMetadataReader(resource);//如果扫描到的类符合容器配置的过滤规则if (isCandidateComponent(metadataReader)) {//通过汇编(ASM)读取资源字节码中的Bean定义元信息ScannedGenericBeanDefinition sbd = new ScannedGenericBeanDefinition(metadataReader);//设置Bean定义来源于resourcesbd.setResource(resource);//为元数据元素设置配置资源对象sbd.setSource(resource);//检查Bean是否是一个可实例化的对象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;}
//判断元信息读取器读取的类是否符合容器定义的注解过滤规则
protected boolean isCandidateComponent(MetadataReader metadataReader) throws IOException {//如果读取的类的注解在排除注解过滤规则中，返回falsefor (TypeFilter tf : this.excludeFilters) {if (tf.match(metadataReader, this.metadataReaderFactory)) {return false;}}//如果读取的类的注解在包含的注解的过滤规则中，则返回turefor (TypeFilter tf : this.includeFilters) {if (tf.match(metadataReader, this.metadataReaderFactory)) {return true;}}//如果读取的类的注解既不在排除规则，也不在包含规则中，则返回falsereturn false;}
……
}

//载入注解Bean定义资源
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) {//为容器设置注解Bean定义读取器AnnotatedBeanDefinitionReader reader = new AnnotatedBeanDefinitionReader(beanFactory);//为容器设置类路径Bean定义扫描器ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(beanFactory);//获取容器的Bean名称生成器BeanNameGenerator beanNameGenerator = getBeanNameGenerator();//获取容器的作用域元信息解析器ScopeMetadataResolver scopeMetadataResolver = getScopeMetadataResolver();//为注解Bean定义读取器和类路径扫描器设置Bean名称生成器if (beanNameGenerator != null) {reader.setBeanNameGenerator(beanNameGenerator);scanner.setBeanNameGenerator(beanNameGenerator);}
//为注解Bean定义读取器和类路径扫描器设置作用域元信息解析器if (scopeMetadataResolver != null) {reader.setScopeMetadataResolver(scopeMetadataResolver);scanner.setScopeMetadataResolver(scopeMetadataResolver);}//获取容器定义的Bean定义资源路径String[] configLocations = getConfigLocations();//如果定位的Bean定义资源路径不为空if (configLocations != null) {for (String configLocation : configLocations) {try {//使用当前容器的类加载器加载定位路径的字节码类文件Class<?> clazz = getClassLoader().loadClass(configLocation);if (logger.isInfoEnabled()) {logger.info("Successfully resolved class for [" + configLocation + "]");}reader.register(clazz);}catch (ClassNotFoundException ex) {if (logger.isDebugEnabled()) {logger.debug("Could not load class for config location [" + configLocation +"] - trying package scan. " + ex);}//如果容器类加载器加载定义路径的Bean定义资源失败，则启用
//容器类路径扫描器扫描给定路径包及其子包中的类int count = scanner.scan(configLocation);if (logger.isInfoEnabled()) {if (count == 0) {logger.info("No annotated classes found for specified class/package [" + configLocation + "]");}else {logger.info("Found " + count + " annotated classes in package [" + configLocation + "]");}}}}}}