Spring源码浅析 -- 依赖注入

Ioc已经完成了对配置文件的载入和解析，接下来将会完成Ioc容器的核心功能 依赖注入。

在依赖注入之前，还要进行对bean的生成和初始化，生成方式分为两种JDK自身的方式和引入CGLIB类库的方式。

首先就从触发这一系列过程的入口说起，BeanFactroy.getBean

 

1.bean在BeanFactroy中的生成

getBean方法的具体实现是在AbstractBeanFactory中

	public Object getBean(String name) throws BeansException {
		return doGetBean(name, null, null, false);
	}

 

它会调用doGetBean方法

	@SuppressWarnings("unchecked")
	private <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.
		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 + "'");
				}
			}
			bean = getObjectForBeanInstance(sharedInstance, name, beanName, null);
		}

		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.
			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) {
				markBeanAsCreated(beanName);
			}

			final RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
			checkMergedBeanDefinition(mbd, beanName, args);

			// Guarantee initialization of beans that the current bean depends on.
			String[] dependsOn = mbd.getDependsOn();
			if (dependsOn != null) {
				for (String dependsOnBean : dependsOn) {
					getBean(dependsOnBean);
					registerDependentBean(dependsOnBean, beanName);
				}
			}

			// Create bean instance.
			if (mbd.isSingleton()) {
				sharedInstance = getSingleton(beanName, new ObjectFactory() {
					public Object getObject() throws BeansException {
						try {
							return createBean(beanName, mbd, args);
						}
						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);
			}

			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);
			}

			else {
				String scopeName = mbd.getScope();
				final Scope scope = this.scopes.get(scopeName);
				if (scope == null) {
					throw new IllegalStateException("No Scope registered for scope '" + scopeName + "'");
				}
				try {
					Object scopedInstance = scope.get(beanName, new ObjectFactory() {
						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);
				}
			}
		}

		// Check if required type matches the type of the actual bean instance.
		if (requiredType != null && bean != null && !requiredType.isAssignableFrom(bean.getClass())) {
			throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
		}
		return (T) bean;
	}

 这个方法首先处理beanName（transformedBeanName(name)），因为会用&开头的情况，然后会在以前的singleton缓存中去找需要的bean（getSingleton(beanName)），因为如果是singleton的bean就不用再创建，然后判断此bean是否在此beanfactory中定义（containsBeanDefinition(beanName)），如果没有递归至双亲beanfactory，以上条件不满足的话，接下来得到beandefination的定义（getMergedLocalBeanDefinition(beanName)），开始创建bean，第一步分析此bean的depand-on的情况，先把它们初始化，第二步判断bean的生命周期，如果是singleton的话，使用对应的singletonFactory来生成，如果是prototype的，使用createBean(beanName, mbd, args)方法生成。

 

createBean(beanName, mbd, args)方法的具体实现是在AbstractAutowireCapableBeanFactory中实现

 

	@Override
	protected Object createBean(final String beanName, final RootBeanDefinition mbd, final Object[] args)
			throws BeanCreationException {

		if (logger.isDebugEnabled()) {
			logger.debug("Creating instance of bean '" + beanName + "'");
		}
		// Make sure bean class is actually resolved at this point.
		resolveBeanClass(mbd, beanName);

		// Prepare method overrides.
		try {
			mbd.prepareMethodOverrides();
		}
		catch (BeanDefinitionValidationException ex) {
			throw new BeanDefinitionStoreException(mbd.getResourceDescription(),
					beanName, "Validation of method overrides failed", ex);
		}

		try {
			// Give BeanPostProcessors a chance to return a proxy instead of the target bean instance.
			Object bean = resolveBeforeInstantiation(beanName, mbd);
			if (bean != null) {
				return bean;
			}
		}
		catch (Throwable ex) {
			throw new BeanCreationException(mbd.getResourceDescription(), beanName,
					"BeanPostProcessor before instantiation of bean failed", ex);
		}

		Object beanInstance = doCreateBean(beanName, mbd, args);
		if (logger.isDebugEnabled()) {
			logger.debug("Finished creating instance of bean '" + beanName + "'");
		}
		return beanInstance;
	}

 

除去一些验证工作，创建bean在doCreateBean(beanName, mbd, args)中实现

 

	protected Object doCreateBean(final String beanName, final RootBeanDefinition mbd, final Object[] args) {
		// Instantiate the bean.
		BeanWrapper instanceWrapper = null;
		if (mbd.isSingleton()) {
			instanceWrapper = this.factoryBeanInstanceCache.remove(beanName);
		}
		if (instanceWrapper == null) {
			instanceWrapper = createBeanInstance(beanName, mbd, args);
		}
		final Object bean = (instanceWrapper != null ? instanceWrapper.getWrappedInstance() : null);
		Class beanType = (instanceWrapper != null ? instanceWrapper.getWrappedClass() : null);

		// Allow post-processors to modify the merged bean definition.
		synchronized (mbd.postProcessingLock) {
			if (!mbd.postProcessed) {
				applyMergedBeanDefinitionPostProcessors(mbd, beanType, beanName);
				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() {
				public Object getObject() throws BeansException {
					return getEarlyBeanReference(beanName, mbd, bean);
				}
			});
		}

		// Initialize the bean instance.
		Object exposedObject = bean;
		try {
			populateBean(beanName, mbd, instanceWrapper);
			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 {
			registerDisposableBeanIfNecessary(beanName, bean, mbd);
		}
		catch (BeanDefinitionValidationException ex) {
			throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Invalid destruction signature", ex);
		}

		return exposedObject;
	}

 在此引入一个bean的包装类BeanWrapper，如果是singleton的，先从缓存中取（instanceWrapper = this.factoryBeanInstanceCache.remove(beanName)），如果为null的话 进入createBeanInstance(beanName, mbd, args)方法

 

	protected BeanWrapper createBeanInstance(String beanName, RootBeanDefinition mbd, Object[] args) {
		// Make sure bean class is actually resolved at this point.
		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());
		}

		if (mbd.getFactoryMethodName() != null)  {
			return instantiateUsingFactoryMethod(beanName, mbd, args);
		}

		// Shortcut when re-creating the same bean...
		if (mbd.resolvedConstructorOrFactoryMethod != null && args == null) {
			if (mbd.constructorArgumentsResolved) {
				return autowireConstructor(beanName, mbd, null, null);
			}
			else {
				return instantiateBean(beanName, mbd);
			}
		}

		// Need to determine the constructor...
		Constructor[] ctors = determineConstructorsFromBeanPostProcessors(beanClass, beanName);
		if (ctors != null ||
				mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_CONSTRUCTOR ||
				mbd.hasConstructorArgumentValues() || !ObjectUtils.isEmpty(args))  {
			return autowireConstructor(beanName, mbd, ctors, args);
		}

		// No special handling: simply use no-arg constructor.
		return instantiateBean(beanName, mbd);
	}

 如果此bean配置了工厂方法（mbd.getFactoryMethodName() != null），则使用工厂类进行bean的创建，如果此bean注入了构造器参数（ctors != null），则使用非默认的构造器对应的方法autowireConstructor进行生成，最后一种情况是最常见的，非工厂类，且使用默认无参的构造方法，instantiateBean(beanName, mbd)

 

 

	protected BeanWrapper instantiateBean(final String beanName, final RootBeanDefinition mbd) {
		try {
			Object beanInstance;
			final BeanFactory parent = this;
			if (System.getSecurityManager() != null) {
				beanInstance = AccessController.doPrivileged(new PrivilegedAction<Object>() {
	
					public Object run() {
						return getInstantiationStrategy().instantiate(mbd, beanName, parent);
					}
				}, getAccessControlContext());
			}
			else {
				beanInstance = getInstantiationStrategy().instantiate(mbd, beanName, parent);
			}
			
			BeanWrapper bw = new BeanWrapperImpl(beanInstance);
			initBeanWrapper(bw);
			return bw;
		}
		catch (Throwable ex) {
			throw new BeanCreationException(mbd.getResourceDescription(), beanName, "Instantiation of bean failed", ex);
		}
	}

 在这里首先生成beanInstance对象，然后在对它进行包装（BeanWrapper bw = new BeanWrapperImpl(beanInstance)） 继而完成bean的生成，生成beanInstance 使用getInstantiationStrategy().instantiate(mbd, beanName, parent)方法，在此首先得到InstantiationStrategy的对象，然后进行instantiate，具体实现是在SimpleInstantiationStrategy类中，

 

	public Object instantiate(
			RootBeanDefinition beanDefinition, String beanName, BeanFactory owner) {

		// Don't override the class with CGLIB if no overrides.
		if (beanDefinition.getMethodOverrides().isEmpty()) {
			Constructor constructorToUse = (Constructor) beanDefinition.resolvedConstructorOrFactoryMethod;
			if (constructorToUse == null) {
				final Class clazz = beanDefinition.getBeanClass();
				if (clazz.isInterface()) {
					throw new BeanInstantiationException(clazz, "Specified class is an interface");
				}
				try {
					if (System.getSecurityManager() != null) {
						constructorToUse = AccessController.doPrivileged(new PrivilegedExceptionAction<Constructor>() {
							public Constructor run() throws Exception {
								return clazz.getDeclaredConstructor((Class[]) null);
							}
						});
					} else {
						constructorToUse =	clazz.getDeclaredConstructor((Class[]) null);
					}
					beanDefinition.resolvedConstructorOrFactoryMethod = constructorToUse;
				}
				catch (Exception ex) {
					throw new BeanInstantiationException(clazz, "No default constructor found", ex);
				}
			}
			return BeanUtils.instantiateClass(constructorToUse);
		}
		else {
			// Must generate CGLIB subclass.
			return instantiateWithMethodInjection(beanDefinition, beanName, owner);
		}
	}

 这里首先判断次beandefinetion的override方法是否为空，如果是则使用JDK反射进行生成，否则使用CGLIB进行生成。（这里的判断依据我不太明了，希望大牛们指出..）

 

2.依赖注入

完成了bean对象的生成，接下来就应该是核心的依赖注入了

再次回到AbstractAutowireCapableBeanFactory的doCreateBean方法中，依赖注入发生在populateBean(beanName, mbd, instanceWrapper)方法中

 

	protected void populateBean(String beanName, AbstractBeanDefinition mbd, BeanWrapper bw) {
		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;

		if (!mbd.isSynthetic() && hasInstantiationAwareBeanPostProcessors()) {
			for (BeanPostProcessor bp : getBeanPostProcessors()) {
				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);
			if (hasInstAwareBpps) {
				for (BeanPostProcessor bp : getBeanPostProcessors()) {
					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);
			}
		}

		applyPropertyValues(beanName, mbd, bw, pvs);
	}

 首先判断是否有BeanPostProcessors（hasInstantiationAwareBeanPostProcessors()）如果有，则进行一些修改处理。然后判断是否有自动装配属性（mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_NAME ||
    mbd.getResolvedAutowireMode() == RootBeanDefinition.AUTOWIRE_BY_TYPE）

如果有则进行自动装配。最后应用依赖注入applyPropertyValues(beanName, mbd, bw, pvs);

 

	protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
		if (pvs == null || pvs.isEmpty()) {
			return;
		}

		MutablePropertyValues mpvs = null;
		List<PropertyValue> original;
		
		if (System.getSecurityManager()!= null) {
			if (bw instanceof BeanWrapperImpl) {
				((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext());
			}
		}

		if (pvs instanceof MutablePropertyValues) {
			mpvs = (MutablePropertyValues) pvs;
			if (mpvs.isConverted()) {
				// Shortcut: use the pre-converted values as-is.
				try {
					bw.setPropertyValues(mpvs);
					return;
				}
				catch (BeansException ex) {
					throw new BeanCreationException(
							mbd.getResourceDescription(), beanName, "Error setting property values", ex);
				}
			}
			original = mpvs.getPropertyValueList();
		}
		else {
			original = Arrays.asList(pvs.getPropertyValues());
		}

		TypeConverter converter = getCustomTypeConverter();
		if (converter == null) {
			converter = bw;
		}
		BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter);

		// Create a deep copy, resolving any references for values.
		List<PropertyValue> deepCopy = new ArrayList<PropertyValue>(original.size());
		boolean resolveNecessary = false;
		for (PropertyValue pv : original) {
			if (pv.isConverted()) {
				deepCopy.add(pv);
			}
			else {
				String propertyName = pv.getName();
				Object originalValue = pv.getValue();
				Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
				Object convertedValue = resolvedValue;
				boolean convertible = bw.isWritableProperty(propertyName) &&
						!PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
				if (convertible) {
					convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter);
				}
				// Possibly store converted value in merged bean definition,
				// in order to avoid re-conversion for every created bean instance.
				if (resolvedValue == originalValue) {
					if (convertible) {
						pv.setConvertedValue(convertedValue);
					}
					deepCopy.add(pv);
				}
				else if (convertible && originalValue instanceof TypedStringValue &&
						!((TypedStringValue) originalValue).isDynamic() &&
						!(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) {
					pv.setConvertedValue(convertedValue);
					deepCopy.add(pv);
				}
				else {
					resolveNecessary = true;
					deepCopy.add(new PropertyValue(pv, convertedValue));
				}
			}
		}
		if (mpvs != null && !resolveNecessary) {
			mpvs.setConverted();
		}

		// Set our (possibly massaged) deep copy.
		try {
			bw.setPropertyValues(new MutablePropertyValues(deepCopy));
		}
		catch (BeansException ex) {
			throw new BeanCreationException(
					mbd.getResourceDescription(), beanName, "Error setting property values", ex);
		}
	}

 

这里首先对所有的属性值进行一次深拷贝（deepCopy.add(pv)），将拷贝的值注入bean

最后进行依赖注入，在BeanWrapper中完成 bw.setPropertyValues(new MutablePropertyValues(deepCopy))

具体实现是在BeanWrapper中

 

	@Override
	public void setPropertyValue(PropertyValue pv) throws BeansException {
		PropertyTokenHolder tokens = (PropertyTokenHolder) pv.resolvedTokens;
		if (tokens == null) {
			String propertyName = pv.getName();
			BeanWrapperImpl nestedBw;
			try {
				nestedBw = getBeanWrapperForPropertyPath(propertyName);
			}
			catch (NotReadablePropertyException ex) {
				throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName,
						"Nested property in path '" + propertyName + "' does not exist", ex);
			}
			tokens = getPropertyNameTokens(getFinalPath(nestedBw, propertyName));
			if (nestedBw == this) {
				pv.getOriginalPropertyValue().resolvedTokens = tokens;
			}
			nestedBw.setPropertyValue(tokens, pv);
		}
		else {
			setPropertyValue(tokens, pv);
		}
	}

 这里面主要是生成一个PropertyTokenHolder对象  然后重载到setPropertyValue(tokens, pv)中

	@SuppressWarnings("unchecked")
	private void setPropertyValue(PropertyTokenHolder tokens, PropertyValue pv) throws BeansException {
		String propertyName = tokens.canonicalName;
		String actualName = tokens.actualName;

		if (tokens.keys != null) {
			// Apply indexes and map keys: fetch value for all keys but the last one.
			PropertyTokenHolder getterTokens = new PropertyTokenHolder();
			getterTokens.canonicalName = tokens.canonicalName;
			getterTokens.actualName = tokens.actualName;
			getterTokens.keys = new String[tokens.keys.length - 1];
			System.arraycopy(tokens.keys, 0, getterTokens.keys, 0, tokens.keys.length - 1);
			Object propValue;
			try {
				propValue = getPropertyValue(getterTokens);
			}
			catch (NotReadablePropertyException ex) {
				throw new NotWritablePropertyException(getRootClass(), this.nestedPath + propertyName,
						"Cannot access indexed value in property referenced " +
						"in indexed property path '" + propertyName + "'", ex);
			}
			// Set value for last key.
			String key = tokens.keys[tokens.keys.length - 1];
			if (propValue == null) {
				throw new NullValueInNestedPathException(getRootClass(), this.nestedPath + propertyName,
						"Cannot access indexed value in property referenced " +
						"in indexed property path '" + propertyName + "': returned null");
			}
			else if (propValue.getClass().isArray()) {
				Class requiredType = propValue.getClass().getComponentType();
				int arrayIndex = Integer.parseInt(key);
				Object oldValue = null;
				try {
					if (isExtractOldValueForEditor()) {
						oldValue = Array.get(propValue, arrayIndex);
					}
					Object convertedValue = this.typeConverterDelegate.convertIfNecessary(
							propertyName, oldValue, pv.getValue(), requiredType);
					Array.set(propValue, Integer.parseInt(key), convertedValue);
				}
				catch (IllegalArgumentException ex) {
					PropertyChangeEvent pce =
							new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
					throw new TypeMismatchException(pce, requiredType, ex);
				}
				catch (IllegalStateException ex) {
					PropertyChangeEvent pce =
							new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
					throw new ConversionNotSupportedException(pce, requiredType, ex);
				}
				catch (IndexOutOfBoundsException ex) {
					throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
							"Invalid array index in property path '" + propertyName + "'", ex);
				}
			}
			else if (propValue instanceof List) {
				PropertyDescriptor pd = getCachedIntrospectionResults().getPropertyDescriptor(actualName);
				Class requiredType = GenericCollectionTypeResolver.getCollectionReturnType(
						pd.getReadMethod(), tokens.keys.length);
				List list = (List) propValue;
				int index = Integer.parseInt(key);
				Object oldValue = null;
				if (isExtractOldValueForEditor() && index < list.size()) {
					oldValue = list.get(index);
				}
				try {
					Object convertedValue = this.typeConverterDelegate.convertIfNecessary(
							propertyName, oldValue, pv.getValue(), requiredType);
					if (index < list.size()) {
						list.set(index, convertedValue);
					}
					else if (index >= list.size()) {
						for (int i = list.size(); i < index; i++) {
							try {
								list.add(null);
							}
							catch (NullPointerException ex) {
								throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
										"Cannot set element with index " + index + " in List of size " +
										list.size() + ", accessed using property path '" + propertyName +
										"': List does not support filling up gaps with null elements");
							}
						}
						list.add(convertedValue);
					}
				}
				catch (IllegalArgumentException ex) {
					PropertyChangeEvent pce =
							new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
					throw new TypeMismatchException(pce, requiredType, ex);
				}
			}
			else if (propValue instanceof Map) {
				PropertyDescriptor pd = getCachedIntrospectionResults().getPropertyDescriptor(actualName);
				Class mapKeyType = GenericCollectionTypeResolver.getMapKeyReturnType(
						pd.getReadMethod(), tokens.keys.length);
				Class mapValueType = GenericCollectionTypeResolver.getMapValueReturnType(
						pd.getReadMethod(), tokens.keys.length);
				Map map = (Map) propValue;
				Object convertedMapKey;
				Object convertedMapValue;
				try {
					// IMPORTANT: Do not pass full property name in here - property editors
					// must not kick in for map keys but rather only for map values.
					convertedMapKey = this.typeConverterDelegate.convertIfNecessary(key, mapKeyType);
				}
				catch (IllegalArgumentException ex) {
					PropertyChangeEvent pce =
							new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, null, pv.getValue());
					throw new TypeMismatchException(pce, mapKeyType, ex);
				}
				Object oldValue = null;
				if (isExtractOldValueForEditor()) {
					oldValue = map.get(convertedMapKey);
				}
				try {
					// Pass full property name and old value in here, since we want full
					// conversion ability for map values.
					convertedMapValue = this.typeConverterDelegate.convertIfNecessary(
							propertyName, oldValue, pv.getValue(), mapValueType,
							new MethodParameter(pd.getReadMethod(), -1, tokens.keys.length + 1));
				}
				catch (IllegalArgumentException ex) {
					PropertyChangeEvent pce =
							new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
					throw new TypeMismatchException(pce, mapValueType, ex);
				}
				map.put(convertedMapKey, convertedMapValue);
			}
			else {
				throw new InvalidPropertyException(getRootClass(), this.nestedPath + propertyName,
						"Property referenced in indexed property path '" + propertyName +
						"' is neither an array nor a List nor a Map; returned value was [" + pv.getValue() + "]");
			}
		}

		else {
			PropertyDescriptor pd = pv.resolvedDescriptor;
			if (pd == null || !pd.getWriteMethod().getDeclaringClass().isInstance(this.object)) {
				pd = getCachedIntrospectionResults().getPropertyDescriptor(actualName);
				if (pd == null || pd.getWriteMethod() == null) {
					if (pv.isOptional()) {
						logger.debug("Ignoring optional value for property '" + actualName +
								"' - property not found on bean class [" + getRootClass().getName() + "]");
						return;
					}
					else {
						PropertyMatches matches = PropertyMatches.forProperty(propertyName, getRootClass());
						throw new NotWritablePropertyException(
								getRootClass(), this.nestedPath + propertyName,
								matches.buildErrorMessage(), matches.getPossibleMatches());
					}
				}
				pv.getOriginalPropertyValue().resolvedDescriptor = pd;
			}

			Object oldValue = null;
			try {
				Object originalValue = pv.getValue();
				Object valueToApply = originalValue;
				if (!Boolean.FALSE.equals(pv.conversionNecessary)) {
					if (pv.isConverted()) {
						valueToApply = pv.getConvertedValue();
					}
					else {
						if (isExtractOldValueForEditor() && pd.getReadMethod() != null) {
							final Method readMethod = pd.getReadMethod();
							if (!Modifier.isPublic(readMethod.getDeclaringClass().getModifiers()) && !readMethod.isAccessible()) {
								if (System.getSecurityManager()!= null) {
									AccessController.doPrivileged(new PrivilegedAction<Object>() {
										public Object run() {
											readMethod.setAccessible(true);
											return null;
										}
									});
								}
								else {
									readMethod.setAccessible(true);
								}
							}
							try {
								if (System.getSecurityManager() != null) {
									oldValue = AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
										public Object run() throws Exception {
											return readMethod.invoke(object);
										}
									},acc);
								}
								else {
									oldValue = readMethod.invoke(object);
								}
							}
							catch (Exception ex) {
								if (ex instanceof PrivilegedActionException) {
									ex = ((PrivilegedActionException) ex).getException();
								}
								if (logger.isDebugEnabled()) {
									logger.debug("Could not read previous value of property '" +
											this.nestedPath + propertyName + "'", ex);
								}
							}
						}
						valueToApply = this.typeConverterDelegate.convertIfNecessary(oldValue, originalValue, pd);
					}
					pv.getOriginalPropertyValue().conversionNecessary = (valueToApply != originalValue);
				}
				final Method writeMethod = pd.getWriteMethod();
				if (!Modifier.isPublic(writeMethod.getDeclaringClass().getModifiers()) && !writeMethod.isAccessible()) {
					if (System.getSecurityManager()!= null) {
						AccessController.doPrivileged(new PrivilegedAction<Object>() {
							public Object run() {
								writeMethod.setAccessible(true);
								return null;
							}
						});
					}
					else {
						writeMethod.setAccessible(true);
					}
				}
				final Object value = valueToApply;
				
				if (System.getSecurityManager() != null) {
					try {
						AccessController.doPrivileged(new PrivilegedExceptionAction<Object>() {
							public Object run() throws Exception {
								writeMethod.invoke(object, value);
								return null;
							}
						}, acc);
					} catch (PrivilegedActionException ex) {
						throw ex.getException();
					}
				}
				else {
					writeMethod.invoke(object, value);
				}
					
			}
			catch (InvocationTargetException ex) {
				PropertyChangeEvent propertyChangeEvent =
						new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
				if (ex.getTargetException() instanceof ClassCastException) {
					throw new TypeMismatchException(propertyChangeEvent, pd.getPropertyType(), ex.getTargetException());
				}
				else {
					throw new MethodInvocationException(propertyChangeEvent, ex.getTargetException());
				}
			}
			catch (ConversionException ex) {
				PropertyChangeEvent pce =
						new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
				throw new TypeMismatchException(pce, pd.getPropertyType(), ex);
			}
			catch (IllegalArgumentException ex) {
				PropertyChangeEvent pce =
						new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
				throw new TypeMismatchException(pce, pd.getPropertyType(), ex);
			}
			catch (IllegalStateException ex) {
				PropertyChangeEvent pce =
						new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
				throw new ConversionNotSupportedException(pce, pd.getPropertyType(), ex);
			}
			catch (IllegalAccessException ex) {
				PropertyChangeEvent pce =
						new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
				throw new MethodInvocationException(pce, ex);
			}
			catch (Exception ex) {
				PropertyChangeEvent pce =
					new PropertyChangeEvent(this.rootObject, this.nestedPath + propertyName, oldValue, pv.getValue());
				throw new MethodInvocationException(pce, ex);
			}
		}
	}

 在这个非常长的方法里面真正完成了依赖注入的实现，对property进行类型的判断（propValue.getClass().isArray()，propValue instanceof List，propValue instanceof Map）然后根据类型分别进行注入处理。到此，依赖注入基本到底。