10.Java Spring框架源码分析-IOC-实例化所有非懒加载的单实例bean

目录

• 1. 要研究的代码
• 2. 实例化所有非懒加载的单实例bean
  • 2.1. 获取所有BeanName，一个个创建
  • 2.2. 创建单个bean
  • 2.3. 看看之前创建bean有木有，没有再去创建【不是缓存，而是之前步骤创建的Bean】
  • 2.4. 从缓存中获取，没有再创建
  • 2.5. 先看看能不能返回代理对象，不能再创建
    • 2.5.1. 从代理对象中获取
      • 2.5.1.1. 第一次创建业务bean进到这里的时候并不会返回代理对象
      • 2.5.1.2. 在实例化之前调用
      • 2.5.1.3. 如果有代理对象那么调用
  • 2.6. 真正创建bean实例
    • 2.6.1. 创建bean实例
    • 2.6.2. 为bean的属性赋值
    • 2.6.3. 初始化bean
      • 2.6.3.1. 执行所有BeanPostProcessor的postProcessBeforeInitialization方法
      • 2.6.3.2. 调用自定义的初始化方法【InitializingBean】
      • 2.6.3.3. 调用所有BeanPostProcessor的postProcessAfterInitialization方法
    • 2.6.4. 注册bean的销毁方法

1. 要研究的代码

• finishBeanFactoryInitialization

protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) { 	// Initialize conversion service for this context. 	if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) && 			beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) { 		beanFactory.setConversionService( 				beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)); 	}  	// Register a default embedded value resolver if no bean post-processor 	// (such as a PropertyPlaceholderConfigurer bean) registered any before: 	// at this point, primarily for resolution in annotation attribute values. 	if (!beanFactory.hasEmbeddedValueResolver()) { 		beanFactory.addEmbeddedValueResolver(new StringValueResolver() { 			@Override 			public String resolveStringValue(String strVal) { 				return getEnvironment().resolvePlaceholders(strVal); 			} 		}); 	}  	// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early. 	String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false); 	for (String weaverAwareName : weaverAwareNames) { 		getBean(weaverAwareName); 	}  	// Stop using the temporary ClassLoader for type matching. 	beanFactory.setTempClassLoader(null);  	// Allow for caching all bean definition metadata, not expecting further changes. 	beanFactory.freezeConfiguration();  	// Instantiate all remaining (non-lazy-init) singletons. 	//实例化所有剩下的非懒加载的单实例bean 	beanFactory.preInstantiateSingletons(); } 

这个步骤中尤其重要，他的preInstantiateSingletons会实例化所有非懒加载的单实例bean

2. 实例化所有非懒加载的单实例bean

2.1. 获取所有BeanName，一个个创建

• DefaultListableBeanFactory preInstantiateSingletons

public void preInstantiateSingletons() throws BeansException { 	if (logger.isDebugEnabled()) { 		logger.debug("Pre-instantiating singletons in " + this); 	}  	// Iterate over a copy to allow for init methods which in turn register new bean definitions. 	// While this may not be part of the regular factory bootstrap, it does otherwise work fine. 	List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames);  	// Trigger initialization of all non-lazy singleton beans... 	//遍历所有bean名 	for (String beanName : beanNames) { 		//封装成RootBeanDefinition 		RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName); 		//不是抽象的、是单例的、不是懒加载的 		if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) { 			//是FactoryBean类型的（Spring提供的工厂模式，有一个getObject创建bean） 			if (isFactoryBean(beanName)) { 				final FactoryBean<?> factory = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName); 				boolean isEagerInit; 				if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) { 					isEagerInit = AccessController.doPrivileged(new PrivilegedAction<Boolean>() { 						@Override 						public Boolean run() { 							return ((SmartFactoryBean<?>) factory).isEagerInit(); 						} 					}, getAccessControlContext()); 				} 				else { 					isEagerInit = (factory instanceof SmartFactoryBean && 							((SmartFactoryBean<?>) factory).isEagerInit()); 				} 				if (isEagerInit) { 					getBean(beanName); 				} 			} 			//不是FactoryBean 			else { 				//调用AbstractBeanFactory的getBean 				getBean(beanName); 			} 		} 	}  	// Trigger post-initialization callback for all applicable beans... 	//遍历所有bean 	for (String beanName : beanNames) { 		Object singletonInstance = getSingleton(beanName); 		//如果这个bean是SmartInitializingSingleton类型的 		if (singletonInstance instanceof SmartInitializingSingleton) { 			final SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance; 			if (System.getSecurityManager() != null) { 				AccessController.doPrivileged(new PrivilegedAction<Object>() { 					@Override 					public Object run() { 						smartSingleton.afterSingletonsInstantiated(); 						return null; 					} 				}, getAccessControlContext()); 			} 			else { 				//调用其afterSingletonsInstantiated方法 				smartSingleton.afterSingletonsInstantiated(); 			} 		} 	} } 

2.2. 创建单个bean

• AbstractBeanFactory getBean

@Override public Object getBean(String name) throws BeansException { //传入beanName return doGetBean(name, null, null, false); } 

2.3. 看看之前创建bean有木有，没有再去创建【不是缓存，而是之前步骤创建的Bean】

• doGetBean

protected <T> T doGetBean( 		final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly) 		throws BeansException {  	final String beanName = transformedBeanName(name); 	Object bean;  	// Eagerly check singleton cache for manually registered singletons. 	//从之前预加载的bean中获取 	Object sharedInstance = getSingleton(beanName); 	if (sharedInstance != null && args == null) { 		if (logger.isDebugEnabled()) { 			if (isSingletonCurrentlyInCreation(beanName)) { 				logger.debug("Returning eagerly cached instance of singleton bean '" + beanName + 						"' that is not fully initialized yet - a consequence of a circular reference"); 			} 			else { 				logger.debug("Returning cached instance of singleton bean '" + beanName + "'"); 			} 		} 		//之前预加载的bean中有 		bean = getObjectForBeanInstance(sharedInstance, name, beanName, null); 	} 	//之前预加载的bean中没有 	else { 		// Fail if we're already creating this bean instance: 		// We're assumably within a circular reference. 		if (isPrototypeCurrentlyInCreation(beanName)) { 			throw new BeanCurrentlyInCreationException(beanName); 		}  		// Check if bean definition exists in this factory. 		//通过父BeanFactory获取bean 		BeanFactory parentBeanFactory = getParentBeanFactory(); 		if (parentBeanFactory != null && !containsBeanDefinition(beanName)) { 			// Not found -> check parent. 			String nameToLookup = originalBeanName(name); 			if (args != null) { 				// Delegation to parent with explicit args. 				return (T) parentBeanFactory.getBean(nameToLookup, args); 			} 			else { 				// No args -> delegate to standard getBean method. 				return parentBeanFactory.getBean(nameToLookup, requiredType); 			} 		}  		if (!typeCheckOnly) { 			//标记当前bean已创建 			markBeanAsCreated(beanName); 		}  		try { 			final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName); 			checkMergedBeanDefinition(mbd, beanName, args);  			// Guarantee initialization of beans that the current bean depends on. 			//获取当前bean依赖的其他bean 指的是@DependsOn("。。。。") 			String[] dependsOn = mbd.getDependsOn(); 			if (dependsOn != null) { 				//遍历其他bean 				for (String dep : dependsOn) { 					//如果其他bean也依赖当前bean 					if (isDependent(beanName, dep)) { 					//抛出循环依赖异常 						throw new BeanCreationException(mbd.getResourceDescription(), beanName, 								"Circular depends-on relationship between '" + beanName + "' and '" + dep + "'"); 					} 					//注册依赖bean 					registerDependentBean(dep, beanName); 					//获取依赖bean，获取不到则抛出不存在的异常 					try { 						getBean(dep); 					} 					catch (NoSuchBeanDefinitionException ex) { 						throw new BeanCreationException(mbd.getResourceDescription(), beanName, 								"'" + beanName + "' depends on missing bean '" + dep + "'", ex); 					} 				} 			} 			 			//单实例的 			// Create bean instance. 			if (mbd.isSingleton()) { 				//回调第二个参数的getObject方法，最后调用createBean方法创建bean 				sharedInstance = getSingleton(beanName, new ObjectFactory<Object>() { 					@Override 					public Object getObject() throws BeansException { 						try { 						    //创建bean实例 							return createBean(beanName, mbd, args); 						} 						//创建失败销毁bean 						catch (BeansException ex) { 							// Explicitly remove instance from singleton cache: It might have been put there 							// eagerly by the creation process, to allow for circular reference resolution. 							// Also remove any beans that received a temporary reference to the bean. 							destroySingleton(beanName); 							throw ex; 						} 					} 				}); 				bean = getObjectForBeanInstance(sharedInstance, name, beanName, mbd); 			} 			//prototype的 			else if (mbd.isPrototype()) { 				// It's a prototype -> create a new instance. 				Object prototypeInstance = null; 				try { 					beforePrototypeCreation(beanName); 					prototypeInstance = createBean(beanName, mbd, args); 				} 				finally { 					afterPrototypeCreation(beanName); 				} 				bean = getObjectForBeanInstance(prototypeInstance, name, beanName, mbd); 			} 			//其他的：session等 			else { 				String scopeName = mbd.getScope(); 				final Scope scope = this.scopes.get(scopeName); 				if (scope == null) { 					throw new IllegalStateException("No Scope registered for scope name '" + scopeName + "'"); 				} 				try { 					Object scopedInstance = scope.get(beanName, new ObjectFactory<Object>() { 						@Override 						public Object getObject() throws BeansException { 							beforePrototypeCreation(beanName); 							try { 								return createBean(beanName, mbd, args); 							} 							finally { 								afterPrototypeCreation(beanName); 							} 						} 					}); 					bean = getObjectForBeanInstance(scopedInstance, name, beanName, mbd); 				} 				catch (IllegalStateException ex) { 					throw new BeanCreationException(beanName, 							"Scope '" + scopeName + "' is not active for the current thread; consider " + 							"defining a scoped proxy for this bean if you intend to refer to it from a singleton", 							ex); 				} 			} 		} 		catch (BeansException ex) { 			cleanupAfterBeanCreationFailure(beanName); 			throw ex; 		} 	}  	// Check if required type matches the type of the actual bean instance. 	if (requiredType != null && bean != null && !requiredType.isInstance(bean)) { 		try { 			return getTypeConverter().convertIfNecessary(bean, requiredType); 		} 		catch (TypeMismatchException ex) { 			if (logger.isDebugEnabled()) { 				logger.debug("Failed to convert bean '" + name + "' to required type '" + 						ClassUtils.getQualifiedName(requiredType) + "'", ex); 			} 			throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass()); 		} 	} 	return (T) bean; } 

2.4. 从缓存中获取，没有再创建

• DefaultSingletonBeanRegistry getSingleton

public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) { 	Assert.notNull(beanName, "'beanName' must not be null"); 	//加锁 	synchronized (this.singletonObjects) { 		//从缓存map中获取 		Object singletonObject = this.singletonObjects.get(beanName); 		if (singletonObject == null) { 			if (this.singletonsCurrentlyInDestruction) { 				throw new BeanCreationNotAllowedException(beanName, 						"Singleton bean creation not allowed while singletons of this factory are in destruction " + 						"(Do not request a bean from a BeanFactory in a destroy method implementation!)"); 			} 			if (logger.isDebugEnabled()) { 				logger.debug("Creating shared instance of singleton bean '" + beanName + "'"); 			} 			//bean创建之前调用 			beforeSingletonCreation(beanName); 			boolean newSingleton = false; 			boolean recordSuppressedExceptions = (this.suppressedExceptions == null); 			if (recordSuppressedExceptions) { 				this.suppressedExceptions = new LinkedHashSet<Exception>(); 			} 			try { 				//通过beanFactory创建bean 				singletonObject = singletonFactory.getObject(); 				newSingleton = true; 			} 			catch (IllegalStateException ex) { 				// Has the singleton object implicitly appeared in the meantime -> 				// if yes, proceed with it since the exception indicates that state. 				singletonObject = this.singletonObjects.get(beanName); 				if (singletonObject == null) { 					throw ex; 				} 			} 			catch (BeanCreationException ex) { 				if (recordSuppressedExceptions) { 					for (Exception suppressedException : this.suppressedExceptions) { 						ex.addRelatedCause(suppressedException); 					} 				} 				throw ex; 			} 			finally { 				if (recordSuppressedExceptions) { 					this.suppressedExceptions = null; 				} 				//bean创建之后调用 				afterSingletonCreation(beanName); 			} 			if (newSingleton) { 				//把新创建的bean放入map中（ioc容器） 				addSingleton(beanName, singletonObject); 			} 		} 		return (singletonObject != NULL_OBJECT ? singletonObject : null); 	} } 

2.5. 先看看能不能返回代理对象，不能再创建

• AbstractAutowireCapableBeanFactory createBean

protected Object createBean(String beanName, RootBeanDefinition mbd, Object[] args) throws BeanCreationException { 	if (logger.isDebugEnabled()) { 		logger.debug("Creating instance of bean '" + beanName + "'"); 	} 	//bean的定义 	RootBeanDefinition mbdToUse = mbd;  	// Make sure bean class is actually resolved at this point, and 	// clone the bean definition in case of a dynamically resolved Class 	// which cannot be stored in the shared merged bean definition. 	//拿到bean的类型 	Class<?> resolvedClass = resolveBeanClass(mbd, beanName); 	if (resolvedClass != null && !mbd.hasBeanClass() && mbd.getBeanClassName() != null) { 		mbdToUse = new RootBeanDefinition(mbd); 		mbdToUse.setBeanClass(resolvedClass); 	}  	// Prepare method overrides. 	try { 		mbdToUse.prepareMethodOverrides(); 	} 	catch (BeanDefinitionValidationException ex) { 		throw new BeanDefinitionStoreException(mbdToUse.getResourceDescription(), 				beanName, "Validation of method overrides failed", ex); 	}  	try { 		// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance. 		//这里BeanPostProcessor可以返回代理对象 		Object bean = resolveBeforeInstantiation(beanName, mbdToUse); 		if (bean != null) { 			return bean; 		} 	} 	catch (Throwable ex) { 		throw new BeanCreationException(mbdToUse.getResourceDescription(), beanName, 				"BeanPostProcessor before instantiation of bean failed", ex); 	}  	//真正创建bean 	Object beanInstance = doCreateBean(beanName, mbdToUse, args); 	if (logger.isDebugEnabled()) { 		logger.debug("Finished creating instance of bean '" + beanName + "'"); 	} 	return beanInstance; } 

2.5.1. 从代理对象中获取

2.5.1.1. 第一次创建业务bean进到这里的时候并不会返回代理对象

举个例子，如果我们有一个业务Bean叫Calc，他的代理Bean叫CalcProxy

• 第一次从容器中获取Calc Bean的场景

  • 从容器中获取Calc Bean
  • 进入到这里的时候既没有Bean Calc也没有Bean CalcProxy，所以不会返回代理bean
  • 真正创建业务Bean Calc
  • 然后调用执行所有PostProcessor的postProcessAfterInitialization方法创建代理对象

• 第二次从容器中获取Calc Bean的场景

  • 从容器中获取Calc Bean
  • 由于容器中没有，需要先创建业务Bean Calc
  • 进入到这里的时候已经有了代理Bean CalcProxy，返回

• resolveBeforeInstantiation

protected Object resolveBeforeInstantiation(String beanName, RootBeanDefinition mbd) { 	Object bean = null; 	if (!Boolean.FALSE.equals(mbd.beforeInstantiationResolved)) { 		// Make sure bean class is actually resolved at this point. 		//调用AbstractBeanFactory的hasInstantiationAwareBeanPostProcessors方法查看是否包含InstantiationAwareBeanPostProcessors类型的PostProcessor 		if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) { 			Class<?> targetType = determineTargetType(beanName, mbd); 			if (targetType != null) { 				//调用InstantiationAwareBeanPostProcessor类型的postProcessBeforeInstantiation方法获取代理对象 				bean = applyBeanPostProcessorsBeforeInstantiation(targetType, beanName); 				if (bean != null) { 					//代理对象不为空那么调用postProcessAfterInitialization方法操作bean 					bean = applyBeanPostProcessorsAfterInitialization(bean, beanName); 				} 			} 		} 		mbd.beforeInstantiationResolved = (bean != null); 	} 	return bean; } 

通过调用InstantiationAwareBeanPostProcessor类型的postProcessBeforeInstantiation方法获取代理对象，有的话再调用postProcessAfterInitialization方法操作bean，并返回

2.5.1.2. 在实例化之前调用

• applyBeanPostProcessorsBeforeInstantiation

protected Object applyBeanPostProcessorsBeforeInstantiation(Class<?> beanClass, String beanName) { 	//遍历所有BeanPostProcessor 	for (BeanPostProcessor bp : getBeanPostProcessors()) { 		//如果是InstantiationAwareBeanPostProcessor类型的 		if (bp instanceof InstantiationAwareBeanPostProcessor) { 			InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp; 			//那么调用postProcessBeforeInstantiation方法获取代理对象 			Object result = ibp.postProcessBeforeInstantiation(beanClass, beanName); 			if (result != null) { 				return result; 			} 		} 	} 	return null; } 

2.5.1.3. 如果有代理对象那么调用

• applyBeanPostProcessorsAfterInitialization

public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) 		throws BeansException {  	Object result = existingBean; 	//遍历所有BeanPostProcessor 	for (BeanPostProcessor processor : getBeanPostProcessors()) { 		//调用postProcessAfterInitialization方法操作bean	 		result = processor.postProcessAfterInitialization(result, beanName); 		if (result == null) { 			return result; 		} 	} 	return result; } 

2.6. 真正创建bean实例

• doCreateBean

protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) 		throws BeanCreationException {  	// Instantiate the bean. 	BeanWrapper instanceWrapper = null; 	if (mbd.isSingleton()) { 		instanceWrapper = this.factoryBeanInstanceCache.remove(beanName); 	} 	if (instanceWrapper == null) { 		//创建bean对象 		instanceWrapper = createBeanInstance(beanName, mbd, args); 	} 	final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null); 	Class<?> beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null); 	mbd.resolvedTargetType = beanType;  	// Allow post-processors to modify the merged bean definition. 	synchronized (mbd.postProcessingLock) { 		if (!mbd.postProcessed) { 			try { 				//调用MergedBeanDefinitionPostProcessor的postProcessMergedBeanDefinition方法 				applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName); 			} 			catch (Throwable ex) { 				throw new BeanCreationException(mbd.getResourceDescription(), beanName, 						"Post-processing of merged bean definition failed", ex); 			} 			mbd.postProcessed = true; 		} 	}  	// Eagerly cache singletons to be able to resolve circular references 	// even when triggered by lifecycle interfaces like BeanFactoryAware. 	boolean earlySingletonExposure = (mbd.isSingleton() && this.allowCircularReferences && 			isSingletonCurrentlyInCreation(beanName)); 	if (earlySingletonExposure) { 		if (logger.isDebugEnabled()) { 			logger.debug("Eagerly caching bean '" + beanName + 					"' to allow for resolving potential circular references"); 		} 		addSingletonFactory(beanName, new ObjectFactory<Object>() { 			@Override 			public Object getObject() throws BeansException { 				return getEarlyBeanReference(beanName, mbd, bean); 			} 		}); 	}  	// Initialize the bean instance. 	Object exposedObject = bean; 	try { 		//为bean的属性赋值 		populateBean(beanName, mbd, instanceWrapper); 		if (exposedObject != null) { 			//初始化bean 			exposedObject = initializeBean(beanName, exposedObject, mbd); 		} 	} 	catch (Throwable ex) { 		if (ex instanceof BeanCreationException && beanName.equals(((BeanCreationException) ex).getBeanName())) { 			throw (BeanCreationException) ex; 		} 		else { 			throw new BeanCreationException( 					mbd.getResourceDescription(), beanName, "Initialization of bean failed", ex); 		} 	}  	if (earlySingletonExposure) { 		Object earlySingletonReference = getSingleton(beanName, false); 		if (earlySingletonReference != null) { 			if (exposedObject == bean) { 				exposedObject = earlySingletonReference; 			} 			else if (!this.allowRawInjectionDespiteWrapping && hasDependentBean(beanName)) { 				String[] dependentBeans = getDependentBeans(beanName); 				Set<String> actualDependentBeans = new LinkedHashSet<String>(dependentBeans.length); 				for (String dependentBean : dependentBeans) { 					if (!removeSingletonIfCreatedForTypeCheckOnly(dependentBean)) { 						actualDependentBeans.add(dependentBean); 					} 				} 				if (!actualDependentBeans.isEmpty()) { 					throw new BeanCurrentlyInCreationException(beanName, 							"Bean with name '" + beanName + "' has been injected into other beans [" + 							StringUtils.collectionToCommaDelimitedString(actualDependentBeans) + 							"] in its raw version as part of a circular reference, but has eventually been " + 							"wrapped. This means that said other beans do not use the final version of the " + 							"bean. This is often the result of over-eager type matching - consider using " + 							"'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example."); 				} 			} 		} 	}  	// Register bean as disposable. 	try { 		//注册bean的销毁方法，registerDisposableBeanIfNecessary 		不是调用(beanName, bean, mbd); 	} 	catch (BeanDefinitionValidationException ex) { 		throw new BeanCreationException( 				mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex); 	}  	return exposedObject; } 

创建实例的时候分成以下几个步骤

1. 创建bean实例
2. 为bean的属性赋值
3. 初始化bean

2.6.1. 创建bean实例

• createBeanInstance

protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, Object[] args) { 	// Make sure bean class is actually resolved at this point. 	//获取bean的类型 	Class<?> beanClass = resolveBeanClass(mbd, beanName);  	if (beanClass != null && !Modifier.isPublic(beanClass.getModifiers()) && !mbd.isNonPublicAccessAllowed()) { 		throw new BeanCreationException(mbd.getResourceDescription(), beanName, 				"Bean class isn't public, and non-public access not allowed: " + beanClass.getName()); 	}  	//使用工厂方法创建bean 	if (mbd.getFactoryMethodName() != null) { 		return instantiateUsingFactoryMethod(beanName, mbd, args); 	}  	// Shortcut when re-creating the same bean... 	//调用bean的有参构造方法 	boolean resolved = false; 	boolean autowireNecessary = false; 	if (args == null) { 		synchronized (mbd.constructorArgumentLock) { 			if (mbd.resolvedConstructorOrFactoryMethod != null) { 				resolved = true; 				autowireNecessary = mbd.constructorArgumentsResolved; 			} 		} 	} 	if (resolved) { 		if (autowireNecessary) { 			return autowireConstructor(beanName, mbd, null, null); 		} 		else { 			return instantiateBean(beanName, mbd); 		} 	}  	// Candidate constructors for autowiring? 	Constructor<?>[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName); 	if (ctors != null || mbd.getResolvedAutowireMode() == AUTOWIRE_CONSTRUCTOR || 			mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args)) { 		return autowireConstructor(beanName, mbd, ctors, args); 	}  	// No special handling: simply use no-arg constructor. 	//调用bean的无参构造方法 	return instantiateBean(beanName, mbd); } 

2.6.2. 为bean的属性赋值

• populateBean

protected void populateBean(String beanName, RootBeanDefinition mbd, BeanWrapper bw) { 	//拿到所有的属性值 	PropertyValues pvs = mbd.getPropertyValues();  	if (bw == null) { 		if (!pvs.isEmpty()) { 			throw new BeanCreationException( 					mbd.getResourceDescription(), beanName, "Cannot apply property values to null instance"); 		} 		else { 			// Skip property population phase for null instance. 			return; 		} 	}  	// Give any InstantiationAwareBeanPostProcessors the opportunity to modify the 	// state of the bean before properties are set. This can be used, for example, 	// to support styles of field injection. 	boolean continueWithPropertyPopulation = true;  	//有InstantiationAwareBeanPostProcessor类型的PostProcessor 	if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) { 		//遍历所有PostProcessor 		for (BeanPostProcessor bp : getBeanPostProcessors()) { 			//调用InstantiationAwareBeanPostProcessor的postProcessAfterInstantiation方法 			if (bp instanceof InstantiationAwareBeanPostProcessor) { 				InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp; 				if (!ibp.postProcessAfterInstantiation(bw.getWrappedInstance(), beanName)) { 					continueWithPropertyPopulation = false; 					break; 				} 			} 		} 	}  	if (!continueWithPropertyPopulation) { 		return; 	}  	if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME || 			mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) { 		MutablePropertyValues newPvs = new MutablePropertyValues(pvs);  		// Add property values based on autowire by name if applicable. 		if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME) { 			autowireByName(beanName, mbd, bw, newPvs); 		}  		// Add property values based on autowire by type if applicable. 		if (mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE) { 			autowireByType(beanName, mbd, bw, newPvs); 		}  		pvs = newPvs; 	}  	boolean hasInstAwareBpps = hasInstantiationAwareBeanPostProcessors(); 	boolean needsDepCheck = (mbd.getDependencyCheck() != RootBeanDefinition.DEPENDENCY_CHECK_NONE);  	if (hasInstAwareBpps || needsDepCheck) { 		PropertyDescriptor[] filteredPds = filterPropertyDescriptorsForDependencyCheck(bw, mbd.allowCaching); 		if (hasInstAwareBpps) { 			//遍历所有PostProcessor 			for (BeanPostProcessor bp : getBeanPostProcessors()) { 				//调用InstantiationAwareBeanPostProcessor的postProcessPropertyValues方法 				if (bp instanceof InstantiationAwareBeanPostProcessor) { 					InstantiationAwareBeanPostProcessor ibp = (InstantiationAwareBeanPostProcessor) bp; 					pvs = ibp.postProcessPropertyValues(pvs, filteredPds, bw.getWrappedInstance(), beanName); 					if (pvs == null) { 						return; 					} 				} 			} 		} 		if (needsDepCheck) { 			checkDependencies(beanName, mbd, filteredPds, pvs); 		} 	} 	//调用setter方法为属性赋值 	applyPropertyValues(beanName, mbd, bw, pvs); } 

属性赋值有三个操作

• 调用InstantiationAwareBeanPostProcessor的postProcessAfterInstantiation方法
• 调用InstantiationAwareBeanPostProcessor的postProcessPropertyValues方法
• 调用setter方法为属性赋值

2.6.3. 初始化bean

• initializeBean

protected Object initializeBean(final String beanName, final Object bean, RootBeanDefinition mbd) { 	if (System.getSecurityManager() != null) { 		AccessController.doPrivileged(new PrivilegedAction<Object>() { 			@Override 			public Object run() { 				invokeAwareMethods(beanName, bean); 				return null; 			} 		}, getAccessControlContext()); 	} 	else { 		//执行XXXAware接口的方法 		invokeAwareMethods(beanName, bean); 	}  	Object wrappedBean = bean; 	if (mbd == null || !mbd.isSynthetic()) { 		//执行所有PostProcessor的postProcessBeforeInitialization方法 		wrappedBean = applyBeanPostProcessorsBeforeInitialization(wrappedBean, beanName); 	}  	try { 		//调用自定义的初始化方法 		invokeInitMethods(beanName, wrappedBean, mbd); 	} 	catch (Throwable ex) { 		throw new BeanCreationException( 				(mbd != null ? mbd.getResourceDescription() : null), 				beanName, "Invocation of init method failed", ex); 	} 	if (mbd == null || !mbd.isSynthetic()) { 		//调用所有BeanPostProcessor的postProcessAfterInitialization方法 		wrappedBean = applyBeanPostProcessorsAfterInitialization(wrappedBean, beanName); 	} 	return wrappedBean; } 

2.6.3.1. 执行所有BeanPostProcessor的postProcessBeforeInitialization方法

• applyBeanPostProcessorsBeforeInitialization

public Object applyBeanPostProcessorsBeforeInitialization(Object existingBean, String beanName) 		throws BeansException {  	Object result = existingBean; 	//遍历所有PostProcessor，调用postProcessBeforeInitialization方法 	for (BeanPostProcessor processor : getBeanPostProcessors()) { 		result = processor.postProcessBeforeInitialization(result, beanName); 		if (result == null) { 			return result; 		} 	} 	return result; } 

2.6.3.2. 调用自定义的初始化方法【InitializingBean】

• invokeInitMethods

protected void invokeInitMethods(String beanName, final Object bean, RootBeanDefinition mbd) 		throws Throwable {  	//是InitializingBean对象 	boolean isInitializingBean = (bean instanceof InitializingBean); 	if (isInitializingBean && (mbd == null || !mbd.isExternallyManagedInitMethod("afterPropertiesSet"))) { 		if (logger.isDebugEnabled()) { 			logger.debug("Invoking afterPropertiesSet() on bean with name '" + beanName + "'"); 		} 		if (System.getSecurityManager() != null) { 			try { 				AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() { 					@Override 					public Object run() throws Exception { 						((InitializingBean) bean).afterPropertiesSet(); 						return null; 					} 				}, getAccessControlContext()); 			} 			catch (PrivilegedActionException pae) { 				throw pae.getException(); 			} 		} 		else { 			//调用bean的afterPropertiesSet方法 			((InitializingBean) bean).afterPropertiesSet(); 		} 	}  	if (mbd != null) { 		String initMethodName = mbd.getInitMethodName(); 		if (initMethodName != null && !(isInitializingBean && "afterPropertiesSet".equals(initMethodName)) && 				!mbd.isExternallyManagedInitMethod(initMethodName)) { 			//执行自定义的初始化方法 			invokeCustomInitMethod(beanName, bean, mbd); 		} 	} } 

2.6.3.3. 调用所有BeanPostProcessor的postProcessAfterInitialization方法

这里会创建代理bean

• applyBeanPostProcessorsAfterInitialization

public Object applyBeanPostProcessorsAfterInitialization(Object existingBean, String beanName) 		throws BeansException {  	Object result = existingBean; 	//遍历所有BeanPostProcessor 	for (BeanPostProcessor processor : getBeanPostProcessors()) { 		//调用postProcessAfterInitialization方法 		result = processor.postProcessAfterInitialization(result, beanName); 		if (result == null) { 			return result; 		} 	} 	return result; } 

2.6.4. 注册bean的销毁方法

• registerDisposableBeanIfNecessary

protected void registerDisposableBeanIfNecessary(String beanName, Object bean, RootBeanDefinition mbd) { 	AccessControlContext acc = (System.getSecurityManager() != null ? getAccessControlContext() : null); 	if (!mbd.isPrototype() && requiresDestruction(bean, mbd)) { 		if (mbd.isSingleton()) { 			// Register a DisposableBean implementation that performs all destruction 			// work for the given bean: DestructionAwareBeanPostProcessors, 			// DisposableBean interface, custom destroy method. 			registerDisposableBean(beanName, 					new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc)); 		} 		else { 			// A bean with a custom scope... 			Scope scope = this.scopes.get(mbd.getScope()); 			if (scope == null) { 				throw new IllegalStateException("No Scope registered for scope name '" + mbd.getScope() + "'"); 			} 			scope.registerDestructionCallback(beanName, 					new DisposableBeanAdapter(bean, beanName, mbd, getBeanPostProcessors(), acc)); 		} 	} }