前言
本文接上文Spring 完整实现流程、完整源码分析,主要分析Spring执行refresh()方法前的一些操作!使用注解启动!
启动类
源码分析
1.切入AnnotationConfigApplicationContext
创建AnnotationConfigApplicationContext对象,代码如下
本文主要分析refresh()方法之前的流程,这里this调用如下代码
public AnnotationConfigApplicationContext() {
this.reader = new AnnotatedBeanDefinitionReader(this);
this.scanner = new ClassPathBeanDefinitionScanner(this);
}
因为AnnotationConfigApplicationContext继承了AbstractApplicationContext并且实现了BeanDefinitionRegistry接口那么在实例化AnnotationConfigApplicationContext时会调用继承的AbstractApplicationContext的构造方法
public GenericApplicationContext() {
this.beanFactory = new DefaultListableBeanFactory();
}
这里是直接创建了DefaultListableBeanFactory对象DefaultListableBeanFactory有继承了AbstractAutowireCapableBeanFactory,而AbstractAutowireCapableBeanFactory有继承了AbstractBeanFactory,AbstractBeanFactory又继承了FactoryBeanRegistrySupport,同时FactoryBeanRegistrySupport继承了DefaultSingletonBeanRegistry,DefaultSingletonBeanRegistry的话实际上就是Spring的容器,容器如下
这三个实际上也就是我们常说的Spring的三级缓存,其中我们获取容器中的Bean就是从singletonObjects中获取到的,关于这三级缓存我这里占时不说,后期有空了把这块内容补充进来 @@@@@@@@@
那么看到这里我们就知道Spring容器创建的时候其实就是在这里开始创建的,也就是new DefaultListableBeanFactory();方法开始创建!这里创建好DefaultListableBeanFactory后赋值给了beanFactory
这里特意标注一下这个赋值给GenericApplicationContext的beanFactory流程,因为后面会获取这个beanFactory!完成这个操作后开始执行构造方法AnnotationConfigApplicationContext()中的两行代码
创建new AnnotatedBeanDefinitionReader(this)
这个对象其实就是读取注解标注Bean的描述信息的!
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
这行代码是切入到注解配置工具上去切入方法
public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) {
registerAnnotationConfigProcessors(registry, null);
}
调用registerAnnotationConfigProcessors方法!
public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
BeanDefinitionRegistry registry, @Nullable Object source) {
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)) {
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)) {
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)) {
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;
}
这个方法会返回一些处理器,如下!
- ConfigurationClassPostProcessor
- AutowiredAnnotationBeanPostProcessor
- EventListenerMethodProcessor
- DefaultEventListenerFactory
关于这些处理器后期会单独拎出来分析@@@@@@@
在返回这些处理器之前还会将这些处理器加入到DefaultListableBeanFactory的beanDefinitionNames中进行存储,那么到这里new AnnotatedBeanDefinitionReader(this)流程就走完了,现在开始创建ClassPathBeanDefinitionScanner