Spring框架学习[IoC容器载入Bean资源文件] - JAVA

ML资源进行特殊编码处理 return loadBeanDefinitions(new EncodedResource(resource));

} //这里是载入XML形式Bean定义资源文件方法

public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException { Assert.notNull(encodedResource, EncodedResource must not be null);

if (logger.isInfoEnabled()) { logger.info(Loading XML bean definitions from + encodedResource.getResource());

} //这里是获取线程局部变量

Set currentResources = this.resourcesCurrentlyBeingLoaded.get(); if (currentResources == null) {

currentResources = new HashSet (4); this.resourcesCurrentlyBeingLoaded.set(currentResources);

} if (!currentResources.add(encodedResource)) {

throw new BeanDefinitionStoreException( Detected cyclic loading of + encodedResource + - check your import definitions!);

} try {

//将资源文件转换为IO输入流 InputStream inputStream = encodedResource.getResource().getInputStream();

try { InputSource inputSource = new InputSource(inputStream);

if (encodedResource.getEncoding() != null) { inputSource.setEncoding(encodedResource.getEncoding());

} //具体读取过程的方法

return doLoadBeanDefinitions(inputSource, encodedResource.getResource()); }

finally { inputStream.close();

} }

catch (IOException ex) { throw new BeanDefinitionStoreException(

IOException parsing XML document from + encodedResource.getResource(), ex); }

finally { currentResources.remove(encodedResource);

if (currentResources.isEmpty()) { this.resourcesCurrentlyBeingLoaded.remove();

} }

} //从特定XML文件中实际载入Bean定义资源的方法

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

try { int validationMode = getValidationModeForResource(resource);

//将XML文件转换为DOM对象，解析过程由documentLoader实现 Document doc = this.documentLoader.loadDocument(

inputSource, getEntityResolver(), this.errorHandler, validationMode, isNamespaceAware()); //这里是启动对Bean定义解析的详细过程，该解析过程会用到Spring的Bean

//配置规则 return registerBeanDefinitions(doc, resource);

} catch (BeanDefinitionStoreException ex) {

throw ex; }

catch (SAXParseException ex) { throw new XmlBeanDefinitionStoreException(resource.getDescription(),

Line + ex.getLineNumber() + in XML document from + resource + is invalid, ex); }

catch (SAXException ex) { throw new XmlBeanDefinitionStoreException(resource.getDescription(),

XML document from + resource + is invalid, ex); }

catch (ParserConfigurationException ex) { throw new BeanDefinitionStoreException(resource.getDescription(),

Parser configuration exception parsing XML from + resource, ex); }

catch (IOException ex) { throw new BeanDefinitionStoreException(resource.getDescription(),

IOException parsing XML document from + resource, ex); }

catch (Throwable ex) { throw new BeanDefinitionStoreException(resource.getDescription(),

Unexpected exception parsing XML document from + resource, ex); }

}

通过源码分析，载入Bean定义资源文件的最后一步是将Bean定义资源转换为Document对象，该过程由documentLoader实现。

9. DocumentLoader将Bean定义资源转换为Document对象：

DocumentLoader将Bean定义资源转换成Document对象的源码如下：

[java

//使用标准的JAXP将载入的Bean定义资源转换成document对象 public Document loadDocument(InputSource inputSource, EntityResolver entityResolver,
ErrorHandler errorHandler, int validationMode, boolean namespaceAware) throws Exception { //创建文件解析器工厂
DocumentBuilderFactory factory = createDocumentBuilderFactory(validationM

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