第三章 spring-bean之AbstractBeanFactory（5）

前言

AbstractBeanFactor实现了ConfigurableBeanFactory接口。一棵树有不只有主干，树干，还有花花叶叶。其余接口与实现是BeanFactory的主干与树干的话，那ConfigurableBeanFactory负责管理BeanFactory的花花叶叶。

void setParentBeanFactory(BeanFactory parentBeanFactory) throws IllegalStateException;

	void setBeanClassLoader(ClassLoader beanClassLoader);

	ClassLoader getBeanClassLoader();

	void setTempClassLoader(ClassLoader tempClassLoader);

	ClassLoader getTempClassLoader();

	void setCacheBeanMetadata(boolean cacheBeanMetadata);

	boolean isCacheBeanMetadata();

	void setBeanExpressionResolver(BeanExpressionResolver resolver);

	BeanExpressionResolver getBeanExpressionResolver();

	void setConversionService(ConversionService conversionService);

	ConversionService getConversionService();

	void addPropertyEditorRegistrar(PropertyEditorRegistrar registrar);

	void registerCustomEditor(Class<?> requiredType, Class<? extends PropertyEditor> propertyEditorClass);

	void copyRegisteredEditorsTo(PropertyEditorRegistry registry);

	void setTypeConverter(TypeConverter typeConverter);

	TypeConverter getTypeConverter();

	void addEmbeddedValueResolver(StringValueResolver valueResolver);

	boolean hasEmbeddedValueResolver();

	String resolveEmbeddedValue(String value);

	void addBeanPostProcessor(BeanPostProcessor beanPostProcessor);

	int getBeanPostProcessorCount();

	void registerScope(String scopeName, Scope scope);

	String[] getRegisteredScopeNames();

	Scope getRegisteredScope(String scopeName);

	AccessControlContext getAccessControlContext();

void copyConfigurationFrom(ConfigurableBeanFactory otherFactory);

	void registerAlias(String beanName, String alias) throws BeanDefinitionStoreException;

	void resolveAliases(StringValueResolver valueResolver);

	BeanDefinition getMergedBeanDefinition(String beanName) throws NoSuchBeanDefinitionException;

	boolean isFactoryBean(String name) throws NoSuchBeanDefinitionException;

	void setCurrentlyInCreation(String beanName, boolean inCreation);

	boolean isCurrentlyInCreation(String beanName);

	void registerDependentBean(String beanName, String dependentBeanName);

	String[] getDependentBeans(String beanName);

	String[] getDependenciesForBean(String beanName);

关于parentBeanFactory 变量相关信息

void setParentBeanFactory(BeanFactory parentBeanFactory) throws IllegalStateException;

private BeanFactory parentBeanFactory;

调用方

• org.springframework.beans.factory.support.AbstractBeanFactory
  • containsBean(String)
  • doGetBean(String, Class<T>, Object[], boolean)
  • getAliases(String)
  • getMergedBeanDefinition(String, BeanDefinition, BeanDefinition)
  • getMergedBeanDefinition(String)
  • getType(String)
  • isFactoryBean(String)
  • isPrototype(String)
  • isSingleton(String)
  • isTypeMatch(String, ResolvableType)
• org.springframework.beans.factory.support.DefaultListableBeanFactory
  • checkBeanNotOfRequiredType(Class<?>, DependencyDescriptor)
  • getBean(Class<T>, Object...)
  • isAutowireCandidate(String, DependencyDescriptor, AutowireCandidateResolver)
  • isPrimary(String, Object)
  • resolveNamedBean(Class<T>)
  • toString()

从被调用的方法名能够方法，parentBeanFactory属性主要是在获得或建立bean的时候，须要进行一样的操做。好比getBean方法，在当前beanFactory没有获得bean，就会去parentBeanFactory执行getBean(){去操做一样的方法}。

public <T> T getBean(Class<T> requiredType, Object... args) throws BeansException {
		NamedBeanHolder<T> namedBean = resolveNamedBean(requiredType, args);
		if (namedBean != null) {
			return namedBean.getBeanInstance();
		}
		BeanFactory parent = getParentBeanFactory();
		if (parent != null) {
			return parent.getBean(requiredType, args);
		}
		throw new NoSuchBeanDefinitionException(requiredType);
	}

解读

parentBeanFactory的设计主要是解决在复杂环境的下，当前容器有parent容器的状况。可是这种设计在当前互联网与分布式应用中没法应用到，因此是一个。菜鸟啊我的，感受这个功能已经十分过期了。

关于ClassLoader相关变量

void setBeanClassLoader(ClassLoader beanClassLoader);

private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

public static ClassLoader getDefaultClassLoader() {
		ClassLoader cl = null;
		try {
			cl = Thread.currentThread().getContextClassLoader();
		}
		catch (Throwable ex) {
			// Cannot access thread context ClassLoader - falling back...
		}
		if (cl == null) {
			// No thread context class loader -> use class loader of this class.
			cl = ClassUtils.class.getClassLoader();
			if (cl == null) {
				// getClassLoader() returning null indicates the bootstrap ClassLoader
				try {
					cl = ClassLoader.getSystemClassLoader();
				}
				catch (Throwable ex) {
					// Cannot access system ClassLoader - oh well, maybe the caller can live with null...
				}
			}
		}
		return cl;
	}

org.springframework.aop.aspectj org.springframework.aop.aspectj.annotation org.springframework.aop.config org.springframework.aop.scope org.springframework.beans.factory.support org.springframework.context.annotation org.springframework.context.event org.springframework.context.expression org.springframework.context.support org.springframework.remoting.jaxws

解读

1. 可能会得到三种不一样的类加载器
2. 在不一样应用中，spring的类加载器，可能不其余的类加载器 不同。好比在tomcat容器中，得到的类加载器与spring默认类加载器不同
3. 不建议修改beanClassLoader类加载器的值

conversionService 变量

private ConversionService conversionService;

public void setConversionService(ConversionService conversionService) {
	this.conversionService = conversionService;
}

@Override
public ConversionService getConversionService() {
	return this.conversionService;
}
}

String CONVERSION_SERVICE_BEAN_NAME = "conversionService";
protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
	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));
	}
	.....
}

解读

1. 若是没有配置 ConversionService 子类，默认在容器里面是没有ConversionService实现类的getConversionService返回null
2. 关于 ConversionService 的详解请求第二章 二节spring-core之converter深刻解读

关于BeanPostProcessor相关的变量

private final List<BeanPostProcessor> beanPostProcessors = new ArrayList<BeanPostProcessor>();

/** Indicates whether any InstantiationAwareBeanPostProcessors have been registered */
private boolean hasInstantiationAwareBeanPostProcessors;

/** Indicates whether any DestructionAwareBeanPostProcessors have been registered */
private boolean hasDestructionAwareBeanPostProcessors;

public void addBeanPostProcessor(BeanPostProcessor beanPostProcessor) {
		Assert.notNull(beanPostProcessor, "BeanPostProcessor must not be null");
		this.beanPostProcessors.remove(beanPostProcessor);
		this.beanPostProcessors.add(beanPostProcessor);
		if (beanPostProcessor instanceof InstantiationAwareBeanPostProcessor) {
			this.hasInstantiationAwareBeanPostProcessors = true;
		}
		if (beanPostProcessor instanceof DestructionAwareBeanPostProcessor) {
			this.hasDestructionAwareBeanPostProcessors = true;
		}
}

public int getBeanPostProcessorCount() {
	return this.beanPostProcessors.size();
}

public List<BeanPostProcessor> getBeanPostProcessors() {
	return this.beanPostProcessors;
}

protected boolean hasInstantiationAwareBeanPostProcessors() {
	return this.hasInstantiationAwareBeanPostProcessors;
}

protected boolean hasDestructionAwareBeanPostProcessors() {
	return this.hasDestructionAwareBeanPostProcessors;
}

protected Object getEarlyBeanReference(String beanName, RootBeanDefinition mbd, Object bean) {
	Object exposedObject = bean;
	if (bean != null && !mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
		for (BeanPostProcessor bp : getBeanPostProcessors()) {
			if (bp instanceof SmartInstantiationAwareBeanPostProcessor) {
				SmartInstantiationAwareBeanPostProcessor ibp = (SmartInstantiationAwareBeanPostProcessor) bp;
				exposedObject = ibp.getEarlyBeanReference(exposedObject, beanName);
				if (exposedObject == null) {
					return null;
				}
			}
		}
	}
	return exposedObject;
}

解读

1. beanPostProcessors变量保存了全部BeanPostProcessor实现类，
2. hasDestructionAwareBeanPostProcessors与hasDestructionAwareBeanPostProcessors的做用是避免进行无效的循环操做

RootBeanDefinition相关变量

private boolean cacheBeanMetadata = true;

	protected RootBeanDefinition getMergedBeanDefinition( String beanName, BeanDefinition bd, BeanDefinition containingBd)throws BeanDefinitionStoreException {
		if (containingBd == null && isCacheBeanMetadata()) {
			this.mergedBeanDefinitions.put(beanName, mbd);
		}
	}


	private final Map<String, RootBeanDefinition> mergedBeanDefinitions = new ConcurrentHashMap<String, RootBeanDefinition>(256);

	private final Set<String> alreadyCreated = Collections.newSetFromMap(new ConcurrentHashMap<String, Boolean>(256));
	protected void markBeanAsCreated(String beanName) {
		if (!this.alreadyCreated.contains(beanName)) {
			synchronized (this.mergedBeanDefinitions) {
				if (!this.alreadyCreated.contains(beanName)) {
					clearMergedBeanDefinition(beanName);
					this.alreadyCreated.add(beanName);
				}
			}
		}
	} 
	protected <T> T doGetBean(final String name, final Class<T> requiredType, final Object[] args, boolean typeCheckOnly) throws BeansException {
		if (!typeCheckOnly) {
				markBeanAsCreated(beanName);
			}
		try {
			final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
			checkMergedBeanDefinition(mbd, beanName, args);
		}
	}

解读

1. 不建议修改cacheBeanMetadata的值
2. mergedBeanDefinitions保存了RootBeanDefinition对象，RootBeanDefinition对象才会生成一个对象。其余的beanDefinition实现不会。奇怪的设计。
3. alreadyCreated控制RootBeanDefinition并发建立问题

总结

本节的内容感受比较惨白无力，有些细节点仍是比较重要的。好比RootBeanDefinition，ConversionService，ClassLoad等。其余方面鸟菜啊，感受就是无用就不解读了。