2019独角兽企业重金招聘Python工程师标准>>> 
前言
本文转自“天河聊技术”微信公众号
接着上一篇文章的bean定义解析继续
正文
上一次解析到这个方法org.springframework.beans.factory.xml.XmlBeanDefinitionReader#loadBeanDefinitions(org.springframework.core.io.support.EncodedResource)这行代码
// 加载bean定义 return doLoadBeanDefinitions(inputSource, encodedResource.getResource());
// 加载xml文档 Document doc = doLoadDocument(inputSource, resource);
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception {
return this.documentLoader.loadDocument(inputSource, getEntityResolver(), this.errorHandler,
getValidationModeForResource(resource), isNamespaceAware());
}
isNamespaceAware() 返回XML解析器是否应该具有XML名称空间
进入这个方法org.springframework.beans.factory.xml.XmlBeanDefinitionReader#getValidationModeForResource
protected int getValidationModeForResource(Resource resource) {
int validationModeToUse = getValidationMode();
if (validationModeToUse != VALIDATION_AUTO) {
return validationModeToUse;
}
int detectedMode = detectValidationMode(resource);
if (detectedMode != VALIDATION_AUTO) {
return detectedMode;
}
// Hmm, we didn't get a clear indication... Let's assume XSD,
// since apparently no DTD declaration has been found up until
// detection stopped (before finding the document's root tag).
// 如果没有解析到xml验证模式就采用XSD验证
return VALIDATION_XSD;
}
进入这一行的这个方法
int detectedMode = detectValidationMode(resource);
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.");
}
InputStream inputStream;
try {
inputStream = resource.getInputStream();
}
catch (IOException ex) {
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?", ex);
}
try {
return this.validationModeDetector.detectValidationMode(inputStream);
}
catch (IOException ex) {
throw new BeanDefinitionStoreException("Unable to determine validation mode for [" +
resource + "]: an error occurred whilst reading from the InputStream.", ex);
}
}
进入这一行的这个方法
return this.validationModeDetector.detectValidationMode(inputStream);
org.springframework.util.xml.XmlValidationModeDetector#detectValidationMode
public int detectValidationMode(InputStream inputStream) throws IOException {
// Peek into the file to look for DOCTYPE.
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
try {
boolean isDtdValidated = false;
String content;
while ((content = reader.readLine()) != null) {
// 跳过 注释
content = consumeCommentTokens(content);
if (this.inComment || !StringUtils.hasText(content)) {
continue;
}
// 是否有DOCTYPE声明
if (hasDoctype(content)) {
isDtdValidated = true;
break;
}
// 判断文件是否是以xml标记开头
if (hasOpeningTag(content)) {
// End of meaningful data...
break;
}
}
// 如果找到了DOCTYPE声明就启用DTD验证，如果没有就启用XSD验证
return (isDtdValidated ? VALIDATION_DTD : VALIDATION_XSD);
}
catch (CharConversionException ex) {
// Choked on some character encoding...
// Leave the decision up to the caller. 异常spring就会去猜测一种解析类型去解析
return VALIDATION_AUTO;
}
finally {
reader.close();
}
}
返回到这个方法
org.springframework.beans.factory.xml.XmlBeanDefinitionReader#doLoadDocument
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception {
return this.documentLoader.loadDocument(inputSource, getEntityResolver(), this.errorHandler,
getValidationModeForResource(resource), isNamespaceAware());
}
loadDocument（）加载xmnl文档，底层是java的api
返回到这个方法
org.springframework.beans.factory.xml.XmlBeanDefinitionReader#doLoadBeanDefinitions
// 注册bean定义 return registerBeanDefinitions(doc, resource);
public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
// 创建bean定义阅读器
BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
int countBefore = getRegistry().getBeanDefinitionCount();
// 注册bean定义之前先创建XmlReaderContext
documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
return getRegistry().getBeanDefinitionCount() - countBefore;
}
进入这行代码
// 注册bean定义之前先创建 documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
进入这个方法
public XmlReaderContext createReaderContext(Resource resource) {
return new XmlReaderContext(resource, this.problemReporter, this.eventListener,
this.sourceExtractor, this, getNamespaceHandlerResolver());
}
public NamespaceHandlerResolver getNamespaceHandlerResolver() {
if (this.namespaceHandlerResolver == null) {
this.namespaceHandlerResolver = createDefaultNamespaceHandlerResolver();
}
return this.namespaceHandlerResolver;
}
protected NamespaceHandlerResolver createDefaultNamespaceHandlerResolver() {
ClassLoader cl = (getResourceLoader() != null ? getResourceLoader().getClassLoader() : getBeanClassLoader());
return new DefaultNamespaceHandlerResolver(cl);
}
public DefaultNamespaceHandlerResolver(@Nullable ClassLoader classLoader) {
this(classLoader, DEFAULT_HANDLER_MAPPINGS_LOCATION);
}
public static final String DEFAULT_HANDLER_MAPPINGS_LOCATION = "META-INF/spring.handlers";
可以看到是从这个路径下加载的spring.handlers
返回到这个方法
org.springframework.beans.factory.xml.XmlBeanDefinitionReader#registerBeanDefinitions这一行代码
// 注册bean定义之前先创建 documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
进入这个方法
org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader#registerBeanDefinitions
@Override
public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
this.readerContext = readerContext;
logger.debug("Loading bean definitions");
// 获取xml文档根节点
Element root = doc.getDocumentElement();
// 从xml文件中解析bean定义
doRegisterBeanDefinitions(root);
}
进入这个方法
org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader#doRegisterBeanDefinitions
protected void doRegisterBeanDefinitions(Element root) {
// 加载bean定义
BeanDefinitionParserDelegate parent = this.delegate;
this.delegate = createDelegate(getReaderContext(), root, parent);
// 如果根节点是命名空间 http://www.springframework.org/schema/beans
if (this.delegate.isDefaultNamespace(root)) {
String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
if (StringUtils.hasText(profileSpec)) {
String[] specifiedProfiles = StringUtils.tokenizeToStringArray(
profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);
// 解析环境配置文件
if (!getReaderContext().getEnvironment().acceptsProfiles(specifiedProfiles)) {
if (logger.isInfoEnabled()) {
logger.info("Skipped XML bean definition file due to specified profiles [" + profileSpec +
"] not matching: " + getReaderContext().getResource());
}
return;
}
}
}
进入这个方法
protected BeanDefinitionParserDelegate createDelegate(
XmlReaderContext readerContext, Element root, @Nullable BeanDefinitionParserDelegate parentDelegate) {
// bean定义解析委托
BeanDefinitionParserDelegate delegate = new BeanDefinitionParserDelegate(readerContext);
// bean定义默认配置
delegate.initDefaults(root, parentDelegate);
return delegate;
}
进入这个方法
org.springframework.beans.factory.xml.BeanDefinitionParserDelegate#initDefaults(org.w3c.dom.Element, org.springframework.beans.factory.xml.BeanDefinitionParserDelegate)
public void initDefaults(Element root, @Nullable BeanDefinitionParserDelegate parent) {
// 解析默认的bean定义解析配置
populateDefaults(this.defaults, (parent != null ? parent.defaults : null), root);
// 触发默认的bean定义事件
this.readerContext.fireDefaultsRegistered(this.defaults);
}
进入这个方法
org.springframework.beans.factory.xml.BeanDefinitionParserDelegate#populateDefaults
// 解析beans标签
protected void populateDefaults(DocumentDefaultsDefinition defaults, @Nullable DocumentDefaultsDefinition parentDefaults, Element root) {
// 解析default标签值 是否是default-lazy-init，默认值是false，父配置文件的属性会覆盖子配置文件的属性
String lazyInit = root.getAttribute(DEFAULT_LAZY_INIT_ATTRIBUTE);
if (DEFAULT_VALUE.equals(lazyInit)) {
// Potentially inherited from outer sections, otherwise falling back to false.
lazyInit = (parentDefaults != null ? parentDefaults.getLazyInit() : FALSE_VALUE);
}
defaults.setLazyInit(lazyInit);
// default-merge 是否是这个值，默认值是false
String merge = root.getAttribute(DEFAULT_MERGE_ATTRIBUTE);
if (DEFAULT_VALUE.equals(merge)) {
// Potentially inherited from outer sections, otherwise falling back to false.
merge = (parentDefaults != null ? parentDefaults.getMerge() : FALSE_VALUE);
}
defaults.setMerge(merge);
// default-autowire 是否是这个值，默认值是no
String autowire = root.getAttribute(DEFAULT_AUTOWIRE_ATTRIBUTE);
if (DEFAULT_VALUE.equals(autowire)) {
// Potentially inherited from outer sections, otherwise falling back to 'no'.
autowire = (parentDefaults != null ? parentDefaults.getAutowire() : AUTOWIRE_NO_VALUE);
}
defaults.setAutowire(autowire);
// default-autowire-candidate 是否最为候选bean被自动注入
if (root.hasAttribute(DEFAULT_AUTOWIRE_CANDIDATES_ATTRIBUTE)) {
defaults.setAutowireCandidates(root.getAttribute(DEFAULT_AUTOWIRE_CANDIDATES_ATTRIBUTE));
}
else if (parentDefaults != null) {
defaults.setAutowireCandidates(parentDefaults.getAutowireCandidates());
}
// default-init-method
if (root.hasAttribute(DEFAULT_INIT_METHOD_ATTRIBUTE)) {
defaults.setInitMethod(root.getAttribute(DEFAULT_INIT_METHOD_ATTRIBUTE));
}
else if (parentDefaults != null) {
defaults.setInitMethod(parentDefaults.getInitMethod());
}
// default-destroy-method
if (root.hasAttribute(DEFAULT_DESTROY_METHOD_ATTRIBUTE)) {
defaults.setDestroyMethod(root.getAttribute(DEFAULT_DESTROY_METHOD_ATTRIBUTE));
}
else if (parentDefaults != null) {
defaults.setDestroyMethod(parentDefaults.getDestroyMethod());
}
defaults.setSource(this.readerContext.extractSource(root));
}
返回到这个方法
org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader#doRegisterBeanDefinitions这一行
// 解析环境配置文件
if (!getReaderContext().getEnvironment().acceptsProfiles(specifiedProfiles)) {
下片文章继续。
最后
本次介绍到这里，以上内容仅供参考。