/**
* Load the template BeanDefinition and call {@link #transform(ConfigurableListableBeanFactory,
* BeanDefinition, Element, ParserContext)} to apply runtime configuration value to it. <code>
* builder</code> will be configured to instantiate the bean in the Spring context that we are
* parsing.
*
* <p>During parsing, an instance of {@link
* TemplateBeanDefinitionParser.TemplateComponentDefinition} is pushed onto <code>ParserContext
* </code> so that nested tags can access the enclosing template configuration with a call to
* {@link #findEnclosingTemplateFactory(ParserContext)}. Subclasses can override {@link
* #newComponentDefinition(String, Object, DefaultListableBeanFactory)} to provide a subclass of
* {@link TemplateBeanDefinitionParser.TemplateComponentDefinition} to the parser context if
* necessary.
*/
@Override
protected final void doParse(
Element element, ParserContext parserContext, BeanDefinitionBuilder builder) {
// if we have multiple nested bean definitions, we only parse the template factory
// once. this allows configuration changes made by enclosing bean parsers to be inherited
// by contained beans, which is quite useful.
DefaultListableBeanFactory templateFactory = findEnclosingTemplateFactory(parserContext);
TemplateComponentDefinition tcd = null;
if (templateFactory == null) {
// no nesting -- load the template XML configuration from the classpath.
final BeanFactory parentFactory = (BeanFactory) parserContext.getRegistry();
templateFactory = new DefaultListableBeanFactory(parentFactory);
// load template bean definitions
DefaultResourceLoader loader = new DefaultResourceLoader();
XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(templateFactory);
reader.setResourceLoader(loader);
reader.setEntityResolver(new ResourceEntityResolver(loader));
reader.loadBeanDefinitions(templateResource);
// propagate factory post-processors from the source factory into the template
// factory.
BeanDefinition ppChain = new RootBeanDefinition(ChainingBeanFactoryPostProcessor.class);
ppChain.getPropertyValues().addPropertyValue("targetFactory", templateFactory);
parserContext.getReaderContext().registerWithGeneratedName(ppChain);
// push component definition onto the parser stack for the benefit of
// nested bean definitions.
tcd =
newComponentDefinition(
element.getNodeName(), parserContext.extractSource(element), templateFactory);
parserContext.pushContainingComponent(tcd);
}
try {
// allow subclasses to apply overrides to the template bean definition.
BeanDefinition def = templateFactory.getBeanDefinition(templateId);
transform(templateFactory, def, element, parserContext);
// setup our factory bean to instantiate the modified bean definition upon request.
builder.addPropertyValue("beanFactory", templateFactory);
builder.addPropertyValue("beanName", templateId);
builder.getRawBeanDefinition().setAttribute("id", def.getAttribute("id"));
} finally {
if (tcd != null) parserContext.popContainingComponent();
}
}
/**
* Loads the bean definitions via an XmlBeanDefinitionReader.
*
* @see org.springframework.beans.factory.xml.XmlBeanDefinitionReader
* @see #initBeanDefinitionReader
* @see #loadBeanDefinitions
*/
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws IOException {
// Create a new XmlBeanDefinitionReader for the given BeanFactory.
XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);
// Configure the bean definition reader with this context's
// resource loading environment.
beanDefinitionReader.setResourceLoader(this);
beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));
// Allow a subclass to provide custom initialization of the reader,
// then proceed with actually loading the bean definitions.
initBeanDefinitionReader(beanDefinitionReader);
loadBeanDefinitions(beanDefinitionReader);
}
/**
* 通过XmlBeanDefinitionReader 来加载bean definition.第三步.
*
* <p>当然,可能存在其他非xml形式的配置加载,所以这个从refreshablApplicationConetext类中抽象出模板方法,在子类来实现
*
* <p>Loads the bean definitions via an XmlBeanDefinitionReader.
*
* @see org.springframework.beans.factory.xml.XmlBeanDefinitionReader
* @see #initBeanDefinitionReader
* @see #loadBeanDefinitions
*/
@Override
protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory)
throws BeansException, IOException {
// DefaultListableBeanFactory 中实现了BeanDefinitionRegistry ,reader会将解析好的bean definition 注册到该对象上
XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);
// 配置资源使用的环境,一般用的比较少,打包一般只配置对应的环境配置
beanDefinitionReader.setEnvironment(this.getEnvironment());
// this 继承了 DefaultResourceLoader类,所以其如果不是classpath的话,最终会调用filesystem的getResourcebypath
// 实际上,这就是程序式ioc的第一步,定义resourceLoader
beanDefinitionReader.setResourceLoader(this);
beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));
// 允许子类提供自定义的reader初始化,然后进行实际的加载bean definition工作
initBeanDefinitionReader(beanDefinitionReader);
loadBeanDefinitions(beanDefinitionReader);
}
/*初始化方法*/
public void init() {
beanDefinitionReader =
new XmlBeanDefinitionReader((BeanDefinitionRegistry) applicationContext.getBeanFactory());
beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(applicationContext));
}
