1 创建上下文
context = createApplicationContext();
这里创建了spring对于不同web环境创房间的上下文
ApplicationContextFactory DEFAULT = (webApplicationType) -> {
try {
switch (webApplicationType) {
case SERVLET:
// mvc默认创建上下文
return new AnnotationConfigServletWebServerApplicationContext();
case REACTIVE:
return new AnnotationConfigReactiveWebServerApplicationContext();
default:
return new AnnotationConfigApplicationContext();
}
}
catch (Exception ex) {}
};
AnnotationConfigServletWebServerApplicationContext架构图如下
AnnotationConfigServletWebServerApplicationContext会初始化AnnotatedBeanDefinitionReader和ClassPathBeanDefinitionScanner
public AnnotationConfigServletWebServerApplicationContext() {
// 1.1 带注释的Bean定义阅读器
this.reader = new AnnotatedBeanDefinitionReader(this);
// 1.2 类路径Bean定义扫描器
this.scanner = new ClassPathBeanDefinitionScanner(this);
}
父类GenericApplicationContext ,创建了默认的DefaultListableBeanFactory
public GenericApplicationContext() {
this.beanFactory = new DefaultListableBeanFactory();
}
父父类AbstractApplicationContext
public AbstractApplicationContext() {
// 初始化资源解析器
this.resourcePatternResolver = getResourcePatternResolver();
}
protected ResourcePatternResolver getResourcePatternResolver() {
return new PathMatchingResourcePatternResolver(this);
}
主要还是分为两部分 1.1 带注释的Bean定义阅读器 1.2 类路径Bean定义扫描器
1.1 初始化AnnotatedBeanDefinitionReader
AnnotatedBeanDefinitionReader的构造器
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);
// 加入一些基本的功能性质的beandeDefinition
AnnotationConfigUtils.registerAnnotationConfigProcessors(this.registry);
}
代码很长，但是很简单，注入一些功能性且稍后流程必备的RootBeanDefinition
public static final String CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME="org.springframework.context.annotation.internalConfigurationAnnotationProcessor";
public static final String AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME="org.springframework.context.annotation.internalAutowiredAnnotationProcessor";
public static final String COMMON_ANNOTATION_PROCESSOR_BEAN_NAME="org.springframework.context.annotation.internalCommonAnnotationProcessor";
public static final String PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME ="org.springframework.context.annotation.internalPersistenceAnnotationProcessor";
private static final String PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor";
public static final String EVENT_LISTENER_PROCESSOR_BEAN_NAME="org.springframework.context.event.internalEventListenerProcessor";
public static final String EVENT_LISTENER_FACTORY_BEAN_NAME="org.springframework.context.event.internalEventListenerFactory";
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);
// ConfigurationClassPostProcessor 用于解析@Component、@ComponentScans、@Bean等等
// 用于提供spring的配置类的自动扫描等等
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));
}
// AutowiredAnnotationBeanPostProcessor spring提供注解的依赖注入 @Autowired、@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));
}
// CommonAnnotationBeanPostProcessor java规范的依赖注入 @Resource
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;
}
1.2 初始化ClassPathBeanDefinitionScanner
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();
}
// 设置环境
setEnvironment(environment);
// 设置资源加载器 其实就是AnnotationConfigServletWebServerApplicationContext
setResourceLoader(resourceLoader);
}
protected void registerDefaultFilters() {
// 过滤器增加@Component
this.includeFilters.add(new AnnotationTypeFilter(Component.class));
ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();
// 过滤器增加@ManagedBean注解
try {
this.includeFilters.add(new AnnotationTypeFilter(((Class<? extends Annotation>) ClassUtils.forName("javax.annotation.ManagedBean", cl)), false));}
// 过滤器增加@Named注解
try {
this.includeFilters.add(new AnnotationTypeFilter(((Class<? extends Annotation>) ClassUtils.forName("javax.inject.Named", cl)), false));
}
}
最终注入了5个，分类如下
BeanFactoryPostProcessor：
ConfigurationClassPostProcessor 用于解析@Component、@ComponentScans、@Bean等等
BeanPostProcessor：
AutowiredAnnotationBeanPostProcessor spring提供注解的依赖注入 @Autowired、@Value
CommonAnnotationBeanPostProcessor java规范的依赖注入 @Resource
EventListenerMethodProcessor
其他：
DefaultEventListenerFactory
@ManagedBean、@Named都是java提供的规范注解，spring在这里也做了支持，效果和@Component一样，而@Component的子注解也一样会被注册
2 刷新上下文
refreshContext(context);
private void refreshContext(ConfigurableApplicationContext context) {
if (this.registerShutdownHook) {
shutdownHook.registerApplicationContext(context);
}
refresh(context);
}
protected void refresh(ConfigurableApplicationContext applicationContext) {
applicationContext.refresh();
}
refresh()方法最终还是调用的AbstractApplicationContext的实现
熟悉spring的都知道这里全是spring提供的一个默认的上下文
@Override
public void refresh() throws BeansException, IllegalStateException {
synchronized (this.startupShutdownMonitor) {
// 设置一下当前上下文状态
StartupStep contextRefresh = this.applicationStartup.start("spring.context.refresh");
// 准备上下文
prepareRefresh();
// 设置了serializationId，并且返回创建好的beanFactory
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// 准备bean工厂
// 忽略一些自动注入的bean，增加一些BeanPostProcessor
prepareBeanFactory(beanFactory);
try {
// 空方法，由子类扩展实现
// 这里AnnotationConfigServletWebServerApplicationContext又帮我们注册了一些BeanPostProcessor
postProcessBeanFactory(beanFactory);
// 设置当前上下文状态
StartupStep beanPostProcess = this.applicationStartup.start("spring.context.beans.post-process");
// Invoke factory processors registered as beans in the context.
invokeBeanFactoryPostProcessors(beanFactory);
// Register bean processors that intercept bean creation.
registerBeanPostProcessors(beanFactory);
beanPostProcess.end();
// Initialize message source for this context.
initMessageSource();
// Initialize event multicaster for this context.
initApplicationEventMulticaster();
// Initialize other special beans in specific context subclasses.
onRefresh();
// Check for listener beans and register them.
registerListeners();
// Instantiate all remaining (non-lazy-init) singletons.
finishBeanFactoryInitialization(beanFactory);
// Last step: publish corresponding event.
finishRefresh();
}
catch (BeansException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Exception encountered during context initialization - " +
"cancelling refresh attempt: " + ex);
}
// Destroy already created singletons to avoid dangling resources.
destroyBeans();
// Reset 'active' flag.
cancelRefresh(ex);
// Propagate exception to caller.
throw ex;
}
finally {
// Reset common introspection caches in Spring's core, since we
// might not ever need metadata for singleton beans anymore...
resetCommonCaches();
contextRefresh.end();
}
}
}
这个方法非常复杂，设计到spring大部分的核心流程，这里简单介绍一下调用BeanFactoryPostProcessor的基本流程
2.1 调用BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors 这个方法会spring工厂的后置处理器这里涉及了两个重要的接口BeanDefinitionRegistryPostProcessor和BeanFactoryPostProcessor
BeanDefinitionRegistryPostProcessor 用于提供更多的BeanDefinition
BeanFactoryPostProcessor 用于对beanFactory提供一次更改的机会
public static void invokeBeanFactoryPostProcessors(
ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
// Invoke BeanDefinitionRegistryPostProcessors first, if any.
Set<String> processedBeans = new HashSet<>();
// 如果beanFactory实现了BeanDefinitionRegistry
// 有直接回调postProcessBeanFactory()方法
if (beanFactory instanceof BeanDefinitionRegistry) {
BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
// 遍历默认提供的beanFactoryPostProcessors
for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
BeanDefinitionRegistryPostProcessor registryProcessor =
(BeanDefinitionRegistryPostProcessor) postProcessor;
registryProcessor.postProcessBeanDefinitionRegistry(registry);
registryProcessors.add(registryProcessor);
}
else {
regularPostProcessors.add(postProcessor);
}
}
// Do not initialize FactoryBeans here不要在这里实例化bean
List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
// First, 初始化继承PriorityOrdered的BeanDefinitionRegistryPostProcessor
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
// 排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
// ostProcessBeanDefinitionRegistry
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
currentRegistryProcessors.clear();
// Next, 初始化继承Ordered的BeanDefinitionRegistryPostProcessor.
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
}
}
// 排序
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
// 调用postProcessBeanDefinitionRegistry
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
currentRegistryProcessors.clear();
// Finally, 初始化所用BeanDefinitionRegistryPostProcessor知道不出现为止
boolean reiterate = true;
while (reiterate) {
reiterate = false;
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
for (String ppName : postProcessorNames) {
if (!processedBeans.contains(ppName)) {
currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
processedBeans.add(ppName);
reiterate = true;
}
}
sortPostProcessors(currentRegistryProcessors, beanFactory);
registryProcessors.addAll(currentRegistryProcessors);
invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry, beanFactory.getApplicationStartup());
currentRegistryProcessors.clear();
}
// =始化BeanFactoryPostProcessor扫描BeanDefinitionRegistryPostProcessor出现的BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
// 初始化默认提供的BeanFactoryPostProcessor
invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
}
else {
// 直接调用postProcessBeanFactory
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
}
// Do not initialize FactoryBeans here
// 从容器中获取BeanFactoryPostProcessor
String[] postProcessorNames =
beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
// 分别对继承PriorityOrdered和Ordered和空继承的进行排序分组
List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
List<String> orderedPostProcessorNames = new ArrayList<>();
List<String> nonOrderedPostProcessorNames = new ArrayList<>();
for (String ppName : postProcessorNames) {
if (processedBeans.contains(ppName)) {
// skip - already processed in first phase above
}
else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
}
else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
orderedPostProcessorNames.add(ppName);
}
else {
nonOrderedPostProcessorNames.add(ppName);
}
}
// First, 调用继承PriorityOrdered的postProcessBeanFactory
sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
// Next, 调用继承Ordered的postProcessBeanFactory
List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
for (String postProcessorName : orderedPostProcessorNames) {
orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
sortPostProcessors(orderedPostProcessors, beanFactory);
invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
// Finally, 调用剩下的postProcessBeanFactory
List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
for (String postProcessorName : nonOrderedPostProcessorNames) {
nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
}
invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
// 清理缓存
beanFactory.clearMetadataCache();
}
对于invokeBeanDefinitionRegistryPostProcessors和invokeBeanFactoryPostProcessors方法都是回调对应的接口方法。
invokeBeanFactoryPostProcessors方法简单来说分为两部
1一直寻找BeanDefinition调用postProcessBeanDefinitionRegistry，但是从设计上来说spring的排序并不是完全意义上的排序，每次都会产生新的BeanDefinitionRegistryPostProcessor，spring只能保证按顺序调用新产生的BeanDefinitionRegistryPostProcessor。最后直接调用默认提供的postProcessBeanFactory。
2 因为已经执行完postProcessBeanDefinitionRegistry此时已经没有可以产生新的BeanDefinition，直接排序BeanFactoryPostProcessor，按顺序调用postProcessBeanFactory。
上文提到springboot为我们默认提供了一个BeanFactoryPostProcessor：ConfigurationClassPostProcessor
这个类也真是spring自动化装配的关键，这里提供了其架构图，下文会详细介绍ConfigurationClassPostProcessor是如何对解析@Component、@ComponentScans、@Bean等注解的流程
