前言:前几篇文章已经将BeanDefinition的加载过程大致分析完成,接下来继续分析其他过程。
AbstractApplicationContext#refresh
1 public void refresh() throws BeansException, IllegalStateException {
2 synchronized (this.startupShutdownMonitor) {
3 // Prepare this context for refreshing.
4 // 准备刷新上下文环境
5 prepareRefresh();
6
7 // Tell the subclass to refresh the internal bean factory.
8 // 创建并初始化BeanFactory
9 ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
10
11 // Prepare the bean factory for use in this context.
12 // 填充BeanFactory
13 prepareBeanFactory(beanFactory);
14
15 try {
16 // Allows post-processing of the bean factory in context subclasses.
17 // 提供子类覆盖的额外处理,即子类处理定义的BeanFactoryPostProcess
18 postProcessBeanFactory(beanFactory);
19
20 // Invoke factory processors registered as beans in the context.
21 // 激活各种BeanFactory处理器
22 invokeBeanFactoryPostProcessors(beanFactory);
23
24 // Register bean processors that intercept bean creation.
25 // 注册拦截Bean创建的Bean处理器,即注册BeanPostProcessor
26 registerBeanPostProcessors(beanFactory);
27
28 // Initialize message source for this context.
29 // 初始化上下文中的资源文件,如国际化文件的处理
30 initMessageSource();
31
32 // Initialize event multicaster for this context.
33 // 初始化上下文事件广播器
34 initApplicationEventMulticaster();
35
36 // Initialize other special beans in specific context subclasses.
37 // 给子类扩展初始化其他bean
38 onRefresh();
39
40 // Check for listener beans and register them.
41 // 在所有bean中查找listener bean,然后注册到广播器中
42 registerListeners();
43
44 // Instantiate all remaining (non-lazy-init) singletons.
45 // 初始化剩下的单例Bean(非延迟加载的)
46 finishBeanFactoryInitialization(beanFactory);
47
48 // Last step: publish corresponding event.
49 // 完成刷新过程,通知声明周期处理器lifecycleProcessor刷新过程,同时发出ContextRefreshEvent事件通知别人
50 finishRefresh();
51 } catch (BeansException ex) {
52 if (logger.isWarnEnabled()) {
53 logger.warn("Exception encountered during context initialization - " +
54 "cancelling refresh attempt: " + ex);
55 }
56
57 // Destroy already created singletons to avoid dangling resources.
58 // 销毁已经创建的bean
59 destroyBeans();
60
61 // Reset 'active' flag.
62 // 重置容器激活标签
63 cancelRefresh(ex);
64
65 // Propagate exception to caller.
66 throw ex;
67 } finally {
68 // Reset common introspection caches in Spring's core, since we
69 // might not ever need metadata for singleton beans anymore...
70 resetCommonCaches();
71 }
72 }
73 }
再次回到refresh函数中,前面已经将preparRefresh和obtainFreshBeanFactory函数进行了分析,特别是obtainFreshBeanFactory引申出了非常多的内容,接下来我们看prepareBeanFactory函数。
AbstractApplicationContext#prepareBeanFactory
1 protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
2 // Tell the internal bean factory to use the context's class loader etc.
3 // 设置beanFactory的classLoader
4 beanFactory.setBeanClassLoader(getClassLoader());
5 // 设置beanFactory的表达式语言处理器,Spring3开始增加了对语言表达式,默认可以使用#{bean.xxx}的形式来调用相关属性值
6 beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
7 // 为beanFactory增加一个默认的propertyEditor
8 beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
9
10 // Configure the bean factory with context callbacks.
11 // 添加ApplicationContextAwareProcessor
12 beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
13 // 设置忽略自动装配的接口
14 beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
15 beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
16 beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
17 beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
18 beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
19 beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);
20
21 // BeanFactory interface not registered as resolvable type in a plain factory.
22 // MessageSource registered (and found for autowiring) as a bean.
23 // 设置几个自动装配的特殊规则
24 beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
25 beanFactory.registerResolvableDependency(ResourceLoader.class, this);
26 beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
27 beanFactory.registerResolvableDependency(ApplicationContext.class, this);
28
29 // Register early post-processor for detecting inner beans as ApplicationListeners.
30 beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
31
32 // Detect a LoadTimeWeaver and prepare for weaving, if found.
33 // 增加对AspectJ的支持
34 if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
35 beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
36 // Set a temporary ClassLoader for type matching.
37 beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
38 }
39
40 // Register default environment beans.
41 // 注册默认的系统环境bean
42 if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
43 beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
44 }
45 if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {
46 beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
47 }
48 if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {
49 beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
50 }
51 }
分析:
该函数的逻辑比较简单,就是对BeanFactory的一些属性进行填充,为后期实例化Bean做准备。
AbstractApplicationContext#postProcessBeanFactory该函数的默认实现为空,主要提供给子类进行自定义处理,增强扩展性。
AbstractApplicationContext#invokeBeanFactoryPostProcessors
1 protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
2 PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
3
4 // Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime
5 // (e.g. through an @Bean method registered by ConfigurationClassPostProcessor)
6 if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
7 beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
8 beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
9 }
10 }
该函数的作用是激活BeanFactory的一些处理器。主要逻辑在PostProcessorRegistrationDelegate#invokeBeanFactoryPostProcessors
1 public static void invokeBeanFactoryPostProcessors(
2 ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {
3
4 // Invoke BeanDefinitionRegistryPostProcessors first, if any.
5 // 定义一个set保存所有BeanFactoryPostProcessors
6 Set<String> processedBeans = new HashSet<>();
7
8 // 如果当前BeanFactory为BeanDefinitionRegistry
9 if (beanFactory instanceof BeanDefinitionRegistry) {
10 BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
11 // BeanFactoryPostProcessor集合
12 List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
13 // BeanDefinitionRegistryPostProcessor集合
14 List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();
15
16 // 遍历beanFactoryPostProcessors
17 for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) {
18 // 如果是BeanDefinitionRegistryPostProcessor,则调用BeanDefinitionRegistryPostProcessor进行注册
19 // 同时加入到registryProcessors集合中
20 if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) {
21 BeanDefinitionRegistryPostProcessor registryProcessor =
22 (BeanDefinitionRegistryPostProcessor) postProcessor;
23 registryProcessor.postProcessBeanDefinitionRegistry(registry);
24 registryProcessors.add(registryProcessor);
25 } else {
26 // 否则当做普通的BeanFactoryPostProcessor处理,添加到regularPostProcessors集合中,便于后续处理
27 regularPostProcessors.add(postProcessor);
28 }
29 }
30
31 // Do not initialize FactoryBeans here: We need to leave all regular beans
32 // uninitialized to let the bean factory post-processors apply to them!
33 // Separate between BeanDefinitionRegistryPostProcessors that implement
34 // PriorityOrdered, Ordered, and the rest.
35 // 用于保存当前处理的BeanDefinitionRegistryPostProcessor
36 List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();
37
38 // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
39 // 首先处理实现了PriorityOrdered(邮箱排序接口)的BeanDefinitionRegistryPostProcessor
40 String[] postProcessorNames =
41 beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
42 for (String ppName : postProcessorNames) {
43 if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
44 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
45 processedBeans.add(ppName);
46 }
47 }
48 // 排序
49 sortPostProcessors(currentRegistryProcessors, beanFactory);
50 // 加入registryProcessors集合
51 registryProcessors.addAll(currentRegistryProcessors);
52 // 调用所有实现了PriorityOrdered的BeanDefinitionRegistryPostProcessor的postProcessBeanDefinitionRegistry()
53 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
54 // 清空,以备下次使用
55 currentRegistryProcessors.clear();
56
57 // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
58 // 其次,调用实现了Ordered(普通排序接口)的BeanDefinitionRegistryPostProcessor
59 // 逻辑与上面相同
60 postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
61 for (String ppName : postProcessorNames) {
62 if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) {
63 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
64 processedBeans.add(ppName);
65 }
66 }
67 sortPostProcessors(currentRegistryProcessors, beanFactory);
68 registryProcessors.addAll(currentRegistryProcessors);
69 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
70 currentRegistryProcessors.clear();
71
72 // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
73 // 最后调用其他的BeanDefinitionRegistryPostProcessors
74 boolean reiterate = true;
75 while (reiterate) {
76 reiterate = false;
77 // 获取BeanDefinitionRegistryPostProcessors
78 postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
79 for (String ppName : postProcessorNames) {
80 // 没有包含在processBeans中的(因为包含的都已经处理了)
81 if (!processedBeans.contains(ppName)) {
82 currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
83 processedBeans.add(ppName);
84 reiterate = true;
85 }
86 }
87 // 同样的逻辑
88 sortPostProcessors(currentRegistryProcessors, beanFactory);
89 registryProcessors.addAll(currentRegistryProcessors);
90 invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
91 currentRegistryProcessors.clear();
92 }
93
94 // Now, invoke the postProcessBeanFactory callback of all processors handled so far.
95 // 调用所有BeanDefinitionRegistryPostProcessor(包括手动注册和通过配置文件注册)和BeanFactoryPostProcessor(只有手动注册)的回调函数(postProcessBeanFactory)
96 invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
97 invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
98 } else {
99 // 如果不是BeanDefinitionRegistry只需调用其回调函数(postProcessBeanFactory())即可
100 // Invoke factory processors registered with the context instance.
101 invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory);
102 }
103
104 // Do not initialize FactoryBeans here: We need to leave all regular beans
105 // uninitialized to let the bean factory post-processors apply to them!
106 String[] postProcessorNames =
107 beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false);
108
109 // Separate between BeanFactoryPostProcessors that implement PriorityOrdered,
110 // Ordered, and the rest.
111 // 这里同样需要区分PriorityOrdered、Ordered和没有排序的
112 List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
113 List<String> orderedPostProcessorNames = new ArrayList<>();
114 List<String> nonOrderedPostProcessorNames = new ArrayList<>();
115 for (String ppName : postProcessorNames) {
116 // 已经处理过,则跳过
117 if (processedBeans.contains(ppName)) {
118 // skip - already processed in first phase above
119 } else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { // PriorityOrdered
120 priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class));
121 } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) { // Ordered
122 orderedPostProcessorNames.add(ppName);
123 } else {// 未排序的
124 nonOrderedPostProcessorNames.add(ppName);
125 }
126 }
127
128 // First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered.
129 // PriorityOrdered接口
130 sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
131 invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory);
132
133 // Next, invoke the BeanFactoryPostProcessors that implement Ordered.
134 // Ordered接口
135 List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
136 for (String postProcessorName : orderedPostProcessorNames) {
137 orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
138 }
139 sortPostProcessors(orderedPostProcessors, beanFactory);
140 invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);
141
142 // Finally, invoke all other BeanFactoryPostProcessors.
143 // 未排序的接口
144 List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
145 for (String postProcessorName : nonOrderedPostProcessorNames) {
146 nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
147 }
148 invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory);
149
150 // Clear cached merged bean definitions since the post-processors might have
151 // modified the original metadata, e.g. replacing placeholders in values...
152 beanFactory.clearMetadataCache();
153 }
上述代码较长,但是处理逻辑较为单一,就是对所有的 BeanDefinitionRegistryPostProcessors 、手动注册的 BeanFactoryPostProcessor 以及通过配置文件方式的 BeanFactoryPostProcessor 按照PriorityOrdered 、 Ordered、nonOrdered 三种方式分开处理、调用。
PostProcessorRegistrationDelegate#registerBeanPostProcessors
1 public static void registerBeanPostProcessors(
2 ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {
3
4 // 获取所有的BeanPostProcessor的beanName
5 // 这些beanName都已经全部加载到容器中去,但是没有实例化
6 String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);
7
8 // Register BeanPostProcessorChecker that logs an info message when
9 // a bean is created during BeanPostProcessor instantiation, i.e. when
10 // a bean is not eligible for getting processed by all BeanPostProcessors.
11 // 记录所有的beanProcessor数量
12 int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
13 // 注册BeanPostProcessorChecker,它主要用于在BeanPostProcessor实例化期间记录日志
14 // 当Spring中高配置的后置处理器还没有注册就已经开始了bean的实例化过程,这个时候便会打印BeanPostProcessorChecker中的内容
15 beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));
16
17 // Separate between BeanPostProcessors that implement PriorityOrdered,
18 // Ordered, and the rest.
19 // priorityOrderedPostProcessors保证顺序
20 List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
21 List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
22 // 使用Ordered保证顺序
23 List<String> orderedPostProcessorNames = new ArrayList<>();
24 // 没有顺序
25 List<String> nonOrderedPostProcessorNames = new ArrayList<>();
26 for (String ppName : postProcessorNames) {
27 // PriorityOrdered
28 if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
29 // 调用getBean获取bean实例对象
30 BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
31 priorityOrderedPostProcessors.add(pp);
32 if (pp instanceof MergedBeanDefinitionPostProcessor) {
33 internalPostProcessors.add(pp);
34 }
35 } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
36 // 有序
37 orderedPostProcessorNames.add(ppName);
38 } else {
39 // 无序
40 nonOrderedPostProcessorNames.add(ppName);
41 }
42 }
43
44 // First, register the BeanPostProcessors that implement PriorityOrdered.
45 // 第一步:注册所有实现了PriorityOrdered的BeanPostProcessor
46 // 排序
47 sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
48 // 注册
49 registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);
50
51 // Next, register the BeanPostProcessors that implement Ordered.
52 // 第二步:注册所有实现了Ordered的BeanPostProcessor
53 List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
54 for (String ppName : orderedPostProcessorNames) {
55 BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
56 orderedPostProcessors.add(pp);
57 if (pp instanceof MergedBeanDefinitionPostProcessor) {
58 internalPostProcessors.add(pp);
59 }
60 }
61 // 排序
62 sortPostProcessors(orderedPostProcessors, beanFactory);
63 // 注册
64 registerBeanPostProcessors(beanFactory, orderedPostProcessors);
65
66 // Now, register all regular BeanPostProcessors.
67 // 第三步:注册所有无序的BeanPostProcessor
68 List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
69 for (String ppName : nonOrderedPostProcessorNames) {
70 BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
71 nonOrderedPostProcessors.add(pp);
72 if (pp instanceof MergedBeanDefinitionPostProcessor) {
73 internalPostProcessors.add(pp);
74 }
75 }
76 // 无序的注册,不需要排序
77 registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);
78
79 // Finally, re-register all internal BeanPostProcessors.
80 // 最后注册所有MergedBeanDefinitionPostProcessor类型的BeanPostProcessor
81 sortPostProcessors(internalPostProcessors, beanFactory);
82 registerBeanPostProcessors(beanFactory, internalPostProcessors);
83
84 // Re-register post-processor for detecting inner beans as ApplicationListeners,
85 // moving it to the end of the processor chain (for picking up proxies etc).
86 // 加入ApplicationListenerDetector(探测器)
87 // 重新注册BeanPostProcessor以检测内部bean,因为ApplicationListenerDetector将其移动到处理器链的末尾
88 beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
89 }
上述代码虽稍微有一点长,但整体逻辑还是比较简单,就是对BeanPostProcessor进行注册,按照PriorityOrdered 、 Ordered、nonOrdered三种分支进行处理。
AbstractApplicationContext#initMessageSource
1 protected void initMessageSource() {
2 ConfigurableListableBeanFactory beanFactory = getBeanFactory();
3 // 包含"messageSource"bean
4 if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {
5 this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
6 // Make MessageSource aware of parent MessageSource.
7 // 如果有父类
8 // HierarchicalMessageSource分级处理MessageSource
9 if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
10 HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
11 if (hms.getParentMessageSource() == null) {
12 // Only set parent context as parent MessageSource if no parent MessageSource
13 // registered already.
14 // 如果没有注册父MessageSource,则设置为父类上下文的MessageSource
15 hms.setParentMessageSource(getInternalParentMessageSource());
16 }
17 }
18 if (logger.isTraceEnabled()) {
19 logger.trace("Using MessageSource [" + this.messageSource + "]");
20 }
21 } else {
22 // 使用空MessageSource
23 // Use empty MessageSource to be able to accept getMessage calls.
24 DelegatingMessageSource dms = new DelegatingMessageSource();
25 dms.setParentMessageSource(getInternalParentMessageSource());
26 this.messageSource = dms;
27 beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);
28 if (logger.isTraceEnabled()) {
29 logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");
30 }
31 }
32 }
这里主要初始化MessageSource接口实现类,主要用于国际化。
AbstractApplicationContext#initApplicationEventMulticaster
1 protected void initApplicationEventMulticaster() {
2 ConfigurableListableBeanFactory beanFactory = getBeanFactory();
3 // 如果存在applicationEventMulticaster bean,则获取赋值
4 if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {
5 this.applicationEventMulticaster =
6 beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
7 if (logger.isTraceEnabled()) {
8 logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
9 }
10 } else {
11 // 如果没有,则新建SimpleApplicationEventMulticaster,并完成bean的注册
12 this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
13 beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
14 if (logger.isTraceEnabled()) {
15 logger.trace("No '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "' bean, using " +
16 "[" + this.applicationEventMulticaster.getClass().getSimpleName() + "]");
17 }
18 }
19 }
初始化上下文事件广播器,如果当前容器中存在 applicationEventMulticaster 的 bean,则对 applicationEventMulticaster 赋值,否则新建一个 SimpleApplicationEventMulticaster 的对象(默认的),并完成注册。
AbstractApplicationContext#onRefresh
预留给 AbstractApplicationContext 的子类用于初始化其他特殊的 bean,该方法需要在所有单例 bean 初始化之前调用。
AbstractApplicationContext#registerListeners
1 protected void registerListeners() {
2 // Register statically specified listeners first.
3 // 注册静态监听器
4 for (ApplicationListener<?> listener : getApplicationListeners()) {
5 getApplicationEventMulticaster().addApplicationListener(listener);
6 }
7
8 // Do not initialize FactoryBeans here: We need to leave all regular beans
9 // uninitialized to let post-processors apply to them!
10 String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
11 for (String listenerBeanName : listenerBeanNames) {
12 getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
13 }
14
15 // Publish early application events now that we finally have a multicaster...
16 // 至此,已经完成将监听器注册到ApplicationEventMulticaster中,下面将发布前期的事件给监听器
17 Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
18 this.earlyApplicationEvents = null;
19 if (earlyEventsToProcess != null) {
20 for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
21 getApplicationEventMulticaster().multicastEvent(earlyEvent);
22 }
23 }
24 }
分析:在所有 bean中查找 listener bean,然后注册到广播器中。
AbstractApplicationContext#finishBeanFactoryInitialization
1 protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
2 // Initialize conversion service for this context.
3 // 初始化转换器
4 if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
5 beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
6 beanFactory.setConversionService(
7 beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
8 }
9
10 // Register a default embedded value resolver if no bean post-processor
11 // (such as a PropertyPlaceholderConfigurer bean) registered any before:
12 // at this point, primarily for resolution in annotation attribute values.
13 // 如果之前没有注册bean后置处理器,则注册默认的解析器
14 if (!beanFactory.hasEmbeddedValueResolver()) {
15 beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
16 }
17
18 // 初始化 Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
19 String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
20 for (String weaverAwareName : weaverAwareNames) {
21 getBean(weaverAwareName);
22 }
23
24 // Stop using the temporary ClassLoader for type matching.
25 // 停止使用临时的classLoader
26 beanFactory.setTempClassLoader(null);
27
28 // Allow for caching all bean definition metadata, not expecting further changes.
29 beanFactory.freezeConfiguration();
30
31 // Instantiate all remaining (non-lazy-init) singletons.
32 // 初始化所有剩余的单例(非延迟初始化)
33 beanFactory.preInstantiateSingletons();
34 }
分析:初始化剩下的单例Bean(非延迟加载的)
AbstractApplicationContext#finishRefresh
1 protected void finishRefresh() {
2 // Clear context-level resource caches (such as ASM metadata from scanning).
3 clearResourceCaches();
4
5 // Initialize lifecycle processor for this context.
6 initLifecycleProcessor();
7
8 // Propagate refresh to lifecycle processor first.
9 getLifecycleProcessor().onRefresh();
10
11 // Publish the final event.
12 publishEvent(new ContextRefreshedEvent(this));
13
14 // Participate in LiveBeansView MBean, if active.
15 LiveBeansView.registerApplicationContext(this);
16 }
分析:完成刷新过程,通知生命周期处理器 lifecycleProcessor 刷新过程,同时发出 ContextRefreshEvent 通知别人
总结
本文只是对AbstractApplicationContext的一些方法进行了简要介绍,并没有进行非常详细的分析,因为加载BeanDefinition阶段才是我们的重点,现在BeanDefinition有了,接下来就是看spring是如何实例化Bean了。
by Shawn Chen,2018.12.25日,晚。