Spring扩展自定义的XML标签

在网上搜了许多，感觉不够全面，就找了官方文档，下面记录如何找到对应的文档进入

 网上许多博客都是以dateformat为实例进行编写的，通过官方的foo，能够学到更多的东西，下面贴一段代码，在官方示例上改了一点解析代码：

package com.theory.springdemo;

import java.util.List;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.ManagedList;
import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.util.xml.DomUtils;
import org.w3c.dom.Element;

public class ComponentBeanDefinitionParser extends AbstractBeanDefinitionParser {

    protected AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
        return parseComponentElement2(element);
    }
    // 这个是自己编写的，没有采用官方文档中定义的示例ComponentFactoryBean
    private static AbstractBeanDefinition parseComponentElement2(Element ele) {
        BeanDefinitionBuilder bean = BeanDefinitionBuilder.rootBeanDefinition(Component.class);
        bean.addPropertyValue("name", ele.getAttribute("name"));
        List<Element> childElements = DomUtils.getChildElementsByTagName(ele, "component");
        //List<BeanDefinition> children = new ArrayList<>(); // 不能用这个，转换之类的会报错，ManageList是继承的ArrayList
        ManagedList<BeanDefinition> children = new ManagedList<BeanDefinition>(childElements.size());
        for (Element child : childElements) {
            AbstractBeanDefinition cc = parseComponentElement2(child);
            children.add(cc);
        }
        bean.addPropertyValue("components", children);
        return bean.getBeanDefinition();
    }
    // 以下的代码都是官方文档中的
    private static AbstractBeanDefinition parseComponentElement(Element element) {
        BeanDefinitionBuilder factory = BeanDefinitionBuilder.rootBeanDefinition(ComponentFactoryBean.class);
        factory.addPropertyValue("parent", parseComponent(element));

        List<Element> childElements = DomUtils.getChildElementsByTagName(element, "component");
        if (childElements != null && childElements.size() > 0) {
            parseChildComponents(childElements, factory);
        }
        return factory.getBeanDefinition();
    }

    private static BeanDefinition parseComponent(Element element) {
        BeanDefinitionBuilder component = BeanDefinitionBuilder.rootBeanDefinition(Component.class);
        component.addPropertyValue("name", element.getAttribute("name"));
        return component.getBeanDefinition();
    }

    private static void parseChildComponents(List<Element> childElements, BeanDefinitionBuilder factory) {
        ManagedList<BeanDefinition> children = new ManagedList<BeanDefinition>(childElements.size());
        for (Element element : childElements) {
            children.add(parseComponentElement(element));
        }
        factory.addPropertyValue("children", children);
    }

}