Spring 源码分析（六）--bean的加载整体分析

    通过前面的分析，我们结束了对XML配置文件的解析，接下来将进行bean加载的分析。对于加载bean的功能，在Spring中的调用方式为：

    

或者   MyTestBean  tb = bf.getBean("myTestBean", MyTestBean.class);

一：整体分析

（1.1）AbstractBeanFactory 类

public abstract class AbstractBeanFactory extends FactoryBeanRegistrySupport implements ConfigurableBeanFactory {

    /** Parent bean factory, for bean inheritance support */
    private BeanFactory parentBeanFactory;

    /** ClassLoader to resolve bean class names with, if necessary */
    private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();

    /** ClassLoader to temporarily resolve bean class names with, if necessary */
    private ClassLoader tempClassLoader;

    /** Whether to cache bean metadata or rather reobtain it for every access */
    private boolean cacheBeanMetadata = true;

    /** Resolution strategy for expressions in bean definition values */
    private BeanExpressionResolver beanExpressionResolver;

    /** Spring ConversionService to use instead of PropertyEditors */
    private ConversionService conversionService;

    /** Custom PropertyEditorRegistrars to apply to the beans of this factory */
    private final Set propertyEditorRegistrars =
            new LinkedHashSet(4);

    /** Custom PropertyEditors to apply to the beans of this factory */
    private final Map, Classextends PropertyEditor>> customEditors =
            new HashMap, Classextends PropertyEditor>>(4);

    /** A custom TypeConverter to use, overriding the default PropertyEditor mechanism */
    private TypeConverter typeConverter;

    /** String resolvers to apply e.g. to annotation attribute values */
    private final List embeddedValueResolvers = new LinkedList();

    /** BeanPostProcessors to apply in createBean */
    private final List beanPostProcessors = new ArrayList();

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

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

    /** Map from scope identifier String to corresponding Scope */
    private final Map scopes = new LinkedHashMap(8);

    /** Security context used when running with a SecurityManager */
    private SecurityContextProvider securityContextProvider;

    /** Map from bean name to merged RootBeanDefinition */
    private final Map mergedBeanDefinitions =
            new ConcurrentHashMap(256);

    /** Names of beans that have already been created at least once */
    private final Set alreadyCreated =
            Collections.newSetFromMap(new ConcurrentHashMap(256));

    /** Names of beans that are currently in creation */
    private final ThreadLocal