Spring源码追踪2——xml解析入口-优快云博客

本文详细解析了Spring框架中XML配置文件中如何注册bean定义，并深入讨论了如何处理自定义XML标签，包括解析流程、标签查找机制及环境配置对标签生效的影响。

解析xml节点入口

org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(Element root)

protected void doRegisterBeanDefinitions(Element root) {
    // Any nested <beans> elements will cause recursion in this method. In
    // order to propagate and preserve <beans> default-* attributes correctly,
    // keep track of the current (parent) delegate, which may be null. Create
    // the new (child) delegate with a reference to the parent for fallback purposes,
    // then ultimately reset this.delegate back to its original (parent) reference.
    // this behavior emulates a stack of delegates without actually necessitating one.
    BeanDefinitionParserDelegate parent = this.delegate;
    this.delegate = createDelegate(this.readerContext, root, parent);

    if (this.delegate.isDefaultNamespace(root)) {
        String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
        if (StringUtils.hasText(profileSpec)) {
            Assert.state(this.environment != null, "Environment must be set for evaluating profiles");
            String[] specifiedProfiles = StringUtils.tokenizeToStringArray(
                    profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);
            if (!this.environment.acceptsProfiles(specifiedProfiles)) {
                return;
            }
        }
    }

    preProcessXml(root);
    parseBeanDefinitions(root, this.delegate);
    postProcessXml(root);

    this.delegate = parent;
}