Spring对象解析及注册(二)

protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
            throws BeanDefinitionStoreException {

        try {
            Document doc = doLoadDocument(inputSource, resource);
            int count = registerBeanDefinitions(doc, resource);
            if (logger.isDebugEnabled()) {
                logger.debug("Loaded " + count + " bean definitions from " + resource);
            }
            return count;
        }
        catch (BeanDefinitionStoreException ex) {
            throw ex;
        }
           ......
    }

public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
        //实例化BeanDefinitionDocumentReader
        BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
        //记录统计前BeanDefinition加载个数  
        int countBefore = getRegistry().getBeanDefinitionCount();
        //加载及注册Bean
        documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
        //记录本次加载的BeanDefinition个数
        return getRegistry().getBeanDefinitionCount() - countBefore;
    }

private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {
        if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) {
            importBeanDefinitionResource(ele);
        }
        else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) {
            processAliasRegistration(ele);
        }
        else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) {
            processBeanDefinition(ele, delegate);
        }
        else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {
            // recurse
            doRegisterBeanDefinitions(ele);
        }
    }

/**
     * Process the given bean element, parsing the bean definition
     * and registering it with the registry.
     */
    protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {
        BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);
        if (bdHolder != null) {
            bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);
            try {
                // Register the final decorated instance.
                BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());
            }
            catch (BeanDefinitionStoreException ex) {
                getReaderContext().error("Failed to register bean definition with name '" +
                        bdHolder.getBeanName() + "'", ele, ex);
            }
            // Send registration event.
            getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));
        }
    }

public BeanDefinition parseCustomElement(Element ele, @Nullable BeanDefinition containingBd) {
        //获取对应的命名空间
        String namespaceUri = getNamespaceURI(ele);
        if (namespaceUri == null) {
            return null;
        }
        //根据命名空间找到对应NamespaceHandler
        NamespaceHandler handler = this.readerContext.getNamespaceHandlerResolver().resolve(namespaceUri);
        if (handler == null) {
            error("Unable to locate Spring NamespaceHandler for XML schema namespace [" + namespaceUri + "]", ele);
            return null;
        }
          //调用自定义的NamespaceHandler进行解析
        return handler.parse(ele, new ParserContext(this.readerContext, this, containingBd));
    }