Spring源码学习笔记1

1.Spring中最核心的两个类

1)DefaultListableBeanFactory

　　XmlBeanFactory继承自DefaultListableBeanFactory，DefaultListableBeanFactory是整个bean加载的核心部分，是Spring加载及注册bean的默认实现

2)XmlBeanDefinitionReader

2.示例代码

BeanFactory bf=new XmlBeanFactory(new ClassPathResource("beanFactoryTest.xml"));

XmlBeanFactory.class
public class XmlBeanFactory extends DefaultListableBeanFactory {private final XmlBeanDefinitionReader reader;public XmlBeanFactory(Resource resource) throws BeansException {this(resource, (BeanFactory)null);}public XmlBeanFactory(Resource resource, BeanFactory parentBeanFactory) throws BeansException {super(parentBeanFactory);this.reader = new XmlBeanDefinitionReader(this);this.reader.loadBeanDefinitions(resource);} }
public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {
return this.loadBeanDefinitions(new EncodedResource(resource));
}
public int loadBeanDefinitions(EncodedResource encodedResource){
....　　
　　InputSource inputSource = new InputSource(inputStream);//通过SAX方式解析XML文件
....
　　this.doLoadBeanDefinitions(inputSource, encodedResource.getResource());

}    

3.配置文件的封装

Resource implements InputStreamResource

 

4.AbstractAutowireCapableBeanFactory.ignoreDependencyInterface()

忽略给定接口的自动装配功能

5.加载Bean

protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource) throws BeanDefinitionStoreException {try {int validationMode = this.getValidationModeForResource(resource);//获取xml文件的验证模式 Document doc = this.documentLoader.loadDocument(inputSource, this.getEntityResolver(), this.errorHandler, validationMode, this.isNamespaceAware());//加载XML文件return this.registerBeanDefinitions(doc, resource);//返回注册bean的信息} catch (BeanDefinitionStoreException var5) {throw var5;} catch (SAXParseException var6) {throw new XmlBeanDefinitionStoreException(resource.getDescription(), "Line " + var6.getLineNumber() + " in XML document from " + resource + " is invalid", var6);} catch (SAXException var7) {throw new XmlBeanDefinitionStoreException(resource.getDescription(), "XML document from " + resource + " is invalid", var7);} catch (ParserConfigurationException var8) {throw new BeanDefinitionStoreException(resource.getDescription(), "Parser configuration exception parsing XML from " + resource, var8);} catch (IOException var9) {throw new BeanDefinitionStoreException(resource.getDescription(), "IOException parsing XML document from " + resource, var9);} catch (Throwable var10) {throw new BeanDefinitionStoreException(resource.getDescription(), "Unexpected exception parsing XML document from " + resource, var10);}}

1)获取xml文件的验证模式

getValidationModeForResource(resource); protected int getValidationModeForResource(Resource resource) {
int validationModeToUse = this.getValidationMode();
if (validationModeToUse != 1) {
return validationModeToUse;
} else {
　　　　　　//如果没有设定模式则进行自动检测模式
int detectedMode = this.detectValidationMode(resource);
return detectedMode != 1 ? detectedMode : 3;
}
} protected int detectValidationMode(Resource resource) {if (resource.isOpen()) {throw new BeanDefinitionStoreException("Passed-in Resource [" + resource + "] contains an open stream: " + "cannot determine validation mode automatically. Either pass in a Resource " + "that is able to create fresh streams, or explicitly specify the validationMode " + "on your XmlBeanDefinitionReader instance.");} else {InputStream inputStream;try {inputStream = resource.getInputStream();} catch (IOException var5) {throw new BeanDefinitionStoreException("Unable to determine validation mode for [" + resource + "]: cannot open InputStream. " + "Did you attempt to load directly from a SAX InputSource without specifying the " + "validationMode on your XmlBeanDefinitionReader instance?", var5);}try {
　　　　　　　　　　//将自动检测模式委托给了XmlValidationModeDetector类
　　　　　　　　　　　return this.validationModeDetector.detectValidationMode(inputStream);
　　　　　　　} catch (IOException var4) {
　　　　　　　　　　throw new BeanDefinitionStoreException("Unable to determine validation mode for [" + resource + "]: an error occurred whilst reading from the InputStream.", var4);
　　　　　　　}
　　　　　}
　　}

 

2)加载XML文件，并得到对应的Document

委托给DocumentLoader类

EntityResolver的用法

EntityResolver的作用是项目本身就可以提供一个如何寻找DTD声明的方法，即由程序来实现寻找DTD声明的过程，比如我们将DTD文件放到项目中某处，在实现时直接将此文档读取并返回给SAX即可。这样就避免了通过网络来寻找相应的声明。

验证文件默认的加载方式是通过URL进行网络下载获取，这样会造成延迟，用户体验也不好，一般的做法都是将验证文件放在自己的工程里。

public interface EntityResolver {public abstract InputSource resolveEntity (String publicId,String systemId)throws SAXException, IOException;}

3)返回注册bean的信息

public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
　　　　　　//单一职责原则BeanDefinitionDocumentReader documentReader = this.createBeanDefinitionDocumentReader();documentReader.setEnvironment(this.getEnvironment());int countBefore = this.getRegistry().getBeanDefinitionCount();
　　　　　　//加载及注册beandocumentReader.registerBeanDefinitions(doc, this.createReaderContext(resource));return this.getRegistry().getBeanDefinitionCount() - countBefore;} public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {this.readerContext = readerContext;this.logger.debug("Loading bean definitions");Element root = doc.getDocumentElement();this.doRegisterBeanDefinitions(root);} 解析并注册BeanDefinitions
protected void doRegisterBeanDefinitions(Element root) {String profileSpec = root.getAttribute("profile");if (StringUtils.hasText(profileSpec)) {Assert.state(this.environment != null, "Environment must be set for evaluating profiles");String[] specifiedProfiles = StringUtils.tokenizeToStringArray(profileSpec, ",; ");if (!this.environment.acceptsProfiles(specifiedProfiles)) {return;}}BeanDefinitionParserDelegate parent = this.delegate;this.delegate = this.createHelper(this.readerContext, root, parent);this.preProcessXml(root);//模板方法模式this.parseBeanDefinitions(root, this.delegate);this.postProcessXml(root);this.delegate = parent;}

 

protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {if (delegate.isDefaultNamespace(root)) {NodeList nl = root.getChildNodes();for(int i = 0; i < nl.getLength(); ++i) {Node node = nl.item(i);if (node instanceof Element) {Element ele = (Element)node;if (delegate.isDefaultNamespace(ele)) {this.parseDefaultElement(ele, delegate);//处理默认Bean声明} else {delegate.parseCustomElement(ele);//处理自定义Bean声明}}}} else {delegate.parseCustomElement(root);}}

 

转载于:https://www.cnblogs.com/lvjygogo/p/8974506.html

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