spring註解開發-容器建立全過程(原始碼)
1.Spring容器的建立會經歷refresh()方法【建立重新整理】(以AnnotationConfigApplicationContext為例)
public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
this();
register(annotatedClasses);
refresh();
}
2. refresh()會經歷的過程:
//AbstractApplicationContext.java implement ConfigurableApplicationContext public void refresh() throws BeansException, IllegalStateException { synchronized (this.startupShutdownMonitor) { // Prepare this context for refreshing. prepareRefresh(); // Tell the subclass to refresh the internal bean factory. ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); // Prepare the bean factory for use in this context. prepareBeanFactory(beanFactory); try { // Allows post-processing of the bean factory in context subclasses. postProcessBeanFactory(beanFactory); // Invoke factory processors registered as beans in the context. invokeBeanFactoryPostProcessors(beanFactory); // Register bean processors that intercept bean creation. registerBeanPostProcessors(beanFactory); // 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) { // Destroy already created singletons to avoid dangling resources. destroyBeans(); // Reset 'active' flag. cancelRefresh(ex); // Propagate exception to caller. throw ex; } } }
3. prepareRefresh() 重新整理前的預處理;
1)initPropertySources()初始化一些屬性設定;子類自定義個性化的屬性設定方法;
2)getEnvironment().validateRequiredProperties();檢驗屬性的合法等
3)earlyApplicationEvents= new LinkedHashSet
4.obtainFreshBeanFactory();獲取BeanFactory;
1)refreshBeanFactory();重新整理【建立】BeanFactory;
建立了一個this.beanFactory = new DefaultListableBeanFactory();
設定id;
2)getBeanFactory();返回剛才GenericApplicationContext建立的BeanFactory物件;
3)將建立的BeanFactory【DefaultListableBeanFactory】返回;
5.prepareBeanFactory(beanFactory);BeanFactory的預準備工作(BeanFactory進行一些設定);
1)設定BeanFactory的類載入器、支援表示式解析器...
2)新增部分BeanPostProcessor【ApplicationContextAwareProcessor】
3)設定忽略的自動裝配的介面EnvironmentAware、EmbeddedValueResolverAware、xxx;
4)註冊可以解析的自動裝配;我們能直接在任何元件中自動注入:BeanFactory、ResourceLoader、ApplicationEventPublisher、ApplicationContext
5)新增BeanPostProcessor【ApplicationListenerDetector】
6)新增編譯時的AspectJ;
7)給BeanFactory中註冊一些能用的元件;
environment【ConfigurableEnvironment】、
systemProperties【Map<String, Object>】、
systemEnvironment【Map<String, Object>】
AbstractApplicationContext.java
protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
// Tell the internal bean factory to use the context's class loader etc.
beanFactory.setBeanClassLoader(getClassLoader());
beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
// Configure the bean factory with context callbacks.
beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
//...
// BeanFactory interface not registered as resolvable type in a plain factory.
// MessageSource registered (and found for autowiring) as a bean.
beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
//...
// Register early post-processor for detecting inner beans as ApplicationListeners.
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));
// Detect a LoadTimeWeaver and prepare for weaving, if found.
if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
//...
}
// Register default environment beans.
if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {
beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
}
//...
}
6.postProcessBeanFactory(beanFactory);BeanFactory準備工作完成後進行的後置處理工作;
子類通過重寫這個方法來在BeanFactory建立並預準備完成以後做進一步的設定
以上是BeanFactory的建立及預準備工作
7.invokeBeanFactoryPostProcessors(beanFactory);執行BeanFactoryPostProcessor的方法;
BeanFactoryPostProcessor:BeanFactory的後置處理器。在BeanFactory標準初始化之後執行的;
兩個介面:BeanFactoryPostProcessor、BeanDefinitionRegistryPostProcessor
執行BeanFactoryPostProcessor的方法;
- 先執行BeanDefinitionRegistryPostProcessor
1)獲取所有的BeanDefinitionRegistryPostProcessor;
2)看先執行實現了PriorityOrdered優先順序介面的BeanDefinitionRegistryPostProcessor、
postProcessor.postProcessBeanDefinitionRegistry>(registry)
3)在執行實現了Ordered順序介面的BeanDefinitionRegistryPostProcessor;
postProcessor.postProcessBeanDefinitionRegistry(>registry)
4)最後執行沒有實現任何優先順序或者是順序介面的BeanDefinitionRegistryPostProcessors;
postProcessor.postProcessBeanDefinitionRegistry>(registry)
- 再執行BeanFactoryPostProcessor的方法
1)獲取所有的BeanFactoryPostProcessor
2)看先執行實現了PriorityOrdered優先順序介面的BeanFactoryPostProcessor、
postProcessor.postProcessBeanFactory()
3)在執行實現了Ordered順序介面的BeanFactoryPostProcessor;
postProcessor.postProcessBeanFactory()
4)最後執行沒有實現任何優先順序或者是順序介面的BeanFactoryPostProcessor;
postProcessor.postProcessBeanFactory()
8.registerBeanPostProcessors(beanFactory);
註冊BeanPostProcessor(Bean的後置處理器)【 intercept bean creation】不同介面型別的BeanPostProcessor;在Bean建立前後的執行時機是不一樣的
BeanPostProcessor、
DestructionAwareBeanPostProcessor、
InstantiationAwareBeanPostProcessor、
SmartInstantiationAwareBeanPostProcessor、
MergedBeanDefinitionPostProcessor【internalPostProcessors】
1)獲取所有的BeanPostProcessor;後置處理器都預設可以通過PriorityOrdered、Ordered介面來執行優先順序
2)先註冊PriorityOrdered優先順序介面的BeanPostProcessor;把每一個BeanPostProcessor;新增到BeanFactory中beanFactory.addBeanPostProcessor(postProcessor);
3)再註冊Ordered介面的
4)最後註冊沒有實現任何優先順序介面的
5)最終註冊MergedBeanDefinitionPostProcessor;
6)註冊一個ApplicationListenerDetector;用來在Bean建立完成後檢查是否是ApplicationListener,如果是,則:
applicationContext.addApplicationListener((ApplicationListener<?>) bean);
9.initMessageSource();初始化MessageSource元件(做國際化功能;訊息繫結,訊息解析);
1)獲取BeanFactory
2)看容器中是否有id為messageSource的,型別是MessageSource的元件;如果有賦值給messageSource,如果沒有自己建立一個DelegatingMessageSource;
MessageSource:取出國際化配置檔案中的某個key的值;能按照區域資訊獲取;
3)把建立好的MessageSource註冊在容器中,以後獲取國際化配置檔案的值的時候,可以自動注入MessageSource;
beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource); MessageSource.getMessage(String code, Object[] args, String defaultMessage, Locale locale);
10.initApplicationEventMulticaster();初始化事件派發器;
1)獲取BeanFactory
2)從BeanFactory中獲取applicationEventMulticaster的ApplicationEventMulticaster;
3)如果上一步沒有配置;建立一個SimpleApplicationEventMulticaster
4)將建立的ApplicationEventMulticaster新增到BeanFactory中,以後其他元件直接自動注入
11. onRefresh();留給子容器(子類)
子類重寫這個方法,在容器重新整理的時候可以自定義邏輯;
12. registerListeners();給容器中將所有專案裡面的ApplicationListener註冊進來;
1)從容器中拿到所有的ApplicationListener
2)將每個監聽器新增到事件派發器中;
getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
3)派發之前步驟產生的事件;
13.finishBeanFactoryInitialization(beanFactory);初始化所有剩下的單例項bean;
beanFactory.preInstantiateSingletons();初始化剩下的單例項bean; 實現類是DefaultListableBeanFactory.java
1)獲取容器中的所有Bean,依次進行初始化和建立物件;
2)獲取Bean的定義資訊,即RootBeanDefinition;
RootBeanDefinition bd = >getMergedLocalBeanDefinition(beanName);
3)Bean不是抽象的,是單例項的,不是懶載入;
3.1)判斷是否是FactoryBean;是否是實現FactoryBean介面的Bean;
3.2)不是工廠Bean。利用getBean(beanName)建立物件;
3.2.0 getBean(beanName);等價於 ioc.getBean();
3.2.1
//AbstractBeanFactory.java doGetBean(name, null, null, false);
3.2.2 先獲取快取中儲存的單例項Bean。如果能獲取到說明這個Bean之前被建立過(所有建立過的單例項Bean都會被快取起來)
從private final Map<String, Object> singletonObjects = new ConcurrentHashMap<String, Object>(256);獲取的
3.2.3快取中獲取不到,開始Bean的建立物件流程;
3.2.4標記當前bean已經被建立;
if (!typeCheckOnly) { markBeanAsCreated(beanName); }
3.2.5獲取Bean的定義資訊;
3.2.6【獲取當前Bean依賴的其他Bean;如果有按照getBean()把依賴的Bean先創建出來;】
//AbstractBeanFactory.java String[] dependsOn = mbd.getDependsOn(); if (dependsOn != null) { for (String dep : dependsOn) { if (isDependent(beanName, dep)) { throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Circular depends-on relationship between '" + beanName + "' and '" + dep + "'"); } registerDependentBean(dep, beanName); getBean(dep); } }
3.2.7啟動單例項Bean的建立流程;
啟動單例項Bean的建立流程如下所示:
1)createBean
//AbstractAutowireCapableBeanFactory.java重寫了AbstractBeanFactory.java的createBean
createBean(beanName, mbd, args);
2)讓BeanPostProcessor先攔截返回代理物件;
Object bean = resolveBeforeInstantiation(beanName, mbdToUse);
【InstantiationAwareBeanPostProcessor】:提前執行;
先觸發:postProcessBeforeInstantiation();
bean = applyBeanPostProcessorsBeforeInstantiation(targetType, beanName);
如果有返回值:觸發postProcessAfterInitialization();
if (bean != null) {
bean = applyBeanPostProcessorsAfterInitialization(bean, beanName);
}
3)如果前面的InstantiationAwareBeanPostProcessor沒有返回代理物件;呼叫4)
4)建立bean
Object beanInstance = doCreateBean(beanName, mbdToUse, args);
建立Bean:
1)【建立Bean例項】;createBeanInstance(beanName, mbd, args);
利用工廠方法或者物件的構造器創建出Bean例項;2)applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);呼叫MergedBeanDefinitionPostProcessor的postProcessMergedBeanDefinition(mbd, beanType, beanName);
3)【Bean屬性賦值】populateBean(beanName, mbd, instanceWrapper);-->AbstractAutowireCapableBeanFactory.java
賦值之前:
3.1)拿到InstantiationAwareBeanPostProcessor後置處理器;postProcessAfterInstantiation(); 3.2)拿到InstantiationAwareBeanPostProcessor後置處理器;postProcessPropertyValues();
開始賦值:
3.3)應用Bean屬性的值;為屬性利用setter方法等進行賦值; applyPropertyValues(beanName, mbd, bw, pvs);
4)【Bean初始化】initializeBean(beanName, exposedObject, mbd);
4.1)【執行Aware介面方法】invokeAwareMethods(beanName, bean);執行xxxAware介面的方法
BeanNameAware\BeanClassLoaderAware\BeanFactoryAware4.2)【執行後置處理器初始化之前】applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName);
result = beanProcessor.postProcessBeforeInit> > ialization(result, beanName);
4.3)【執行初始化方法】
invokeInitMethods(beanName, wrappedBean, mbd);
先判斷是否是InitializingBean介面的實現;執行介面規定的初始化;
再判斷是否自定義初始化方法;
4.4)【執行後置處理器初始化之後】applyBeanPostProcessorsAfterInitialization;
result = beanProcessor.postProcessAfterInitialization(result, beanName);
5)註冊Bean的銷燬方法;
//AbstractAutowireCapableBeanFactory.java registerDisposableBeanIfNecessary(beanName, >bean, mbd);
5)將建立的Bean新增到快取中singletonObjects;
ioc容器就是這些Map;很多的Map裡面儲存了單例項Bean,環境資訊...;
所有Bean都利用getBean建立完成以後;
檢查所有的Bean是否是SmartInitializingSingleton介面的;如果是;就執行afterSingletonsInstantiated();
14.finishRefresh();完成BeanFactory的初始化建立工作;IOC容器就建立完成;
1)initLifecycleProcessor();初始化和生命週期有關的後置處理器;
LifecycleProcessor預設從容器中找是否有lifecycleProcessor的元件【LifecycleProcessor】;如果沒有就new DefaultLifecycleProcessor();
加入到容器;
寫一個LifecycleProcessor的實現類,可以在BeanFactory
void onRefresh();
void onClose();
2)getLifecycleProcessor().onRefresh();
拿到前面定義的生命週期處理器(BeanFactory);回撥onRefresh();
3)釋出容器重新整理完成事件;
publishEvent(new ContextRefreshedEvent(this));
4)liveBeansView.registerApplicationContext(this);