Os desenvolvedores definem os beans de aplicação de acordo com as regras de metadados. Compreender como o SF é analisado no BeanDefiniton de acordo com a definição pode ajudar a compreender profundamente a implementação da estrutura. O processo de análise é o seguinte:
Carregamento de recursos
O processo real de carregamento da configuração de metadados do bean do arquivo de recurso é o seguinte: o
carregamento real da definição do bean do arquivo XML especificado começa com XmlBeanDefinitionReader.doLoadBeanDefinitions.
analisar
A análise consiste em duas etapas principais:
1. Analisar o conteúdo do arquivo de recursos em um documento DOM por meio de um analisador SAX.
2. Gerar
o código-fonte BeanDefinition (XmlBeanDefinitionReader.doLoadBeanDefinitions) a partir do documento DOM:
protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
throws BeanDefinitionStoreException {
try {
//将资源解析成Document
Document doc = doLoadDocument(inputSource, resource);
//基于Document生成BeanDefinition
int count = registerBeanDefinitions(doc, resource);
if (logger.isDebugEnabled()) {
logger.debug("Loaded " + count + " bean definitions from " + resource);
}
return count;
}
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);
}
}
Arquivos de recursos para documento
A implementação do Spring é relativamente complexa. O diagrama de relacionamento básico é o seguinte:
Ele usa principalmente SAX para analisar metadados no formato XML em documentos DOM. Tem pouco a ver com o propósito do Spring em si. Não há necessidade de rastrear o código em detalhe. Os alunos interessados podem aprender e entender por si mesmos.
Documento para BeanDefinition
Processo principal
XmlBeanDefinitionReader.registerBeanDefinitions (documento, recurso de recurso)
public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
//生成DOM解析器（负责生成BeanDefinition）
BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
//返回已经注册在BeanFactory中的beanDefinitions数量（支持多个元数据配置文件）
int countBefore = getRegistry().getBeanDefinitionCount();
//生成BeanDefinition
documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
//返回本次beanDefinitions数量（BeanFactory现有数量-生成前记录的数量）
return getRegistry().getBeanDefinitionCount() - countBefore;
}
BeanDefinitionDocumentReader.registerBeanDefinitions (documento, XmlReaderContext readerContext)
É óbvio à primeira vista.
@Override
public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
this.readerContext = readerContext;
doRegisterBeanDefinitions(doc.getDocumentElement());
}
BeanDefinitionDocumentReader.doRegisterBeanDefinitions (raiz do elemento)
Comece a análise a partir do elemento raiz do bean ( ).
//不理解怎么成deprecation
@SuppressWarnings("deprecation") // for Environment.acceptsProfiles(String...)
protected void doRegisterBeanDefinitions(Element root) {
//保存BeanDefinitionParser代理
BeanDefinitionParserDelegate parent = this.delegate;
//生成当前用的BeanDefinitionParser代理，初始化一些默认值
this.delegate = createDelegate(getReaderContext(), root, parent);
//默认命名空间是"http://www.springframework.org/schema/beans"
if (this.delegate.isDefaultNamespace(root)) {
//xml文件中沒有使用到"profile"，有的话需要加载profile相关值 注1
String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
if (StringUtils.hasText(profileSpec)) {
String[] specifiedProfiles = StringUtils.tokenizeToStringArray(
profileSpec, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS);
// We cannot use Profiles.of(...) since profile expressions are not supported
// in XML config. See SPR-12458 for details.
if (!getReaderContext().getEnvironment().acceptsProfiles(specifiedProfiles)) {
if (logger.isDebugEnabled()) {
logger.debug("Skipped XML bean definition file due to specified profiles [" + profileSpec +
"] not matching: " + getReaderContext().getResource());
}
return;
}
}
}
//xml预处理（空实现）
preProcessXml(root);
//生成BeanDefinition，并注册到BeanFactory
parseBeanDefinitions(root, this.delegate);
//xml预处理（空实现）
postProcessXml(root);
//恢复BeanDefinitionParser代理
this.delegate = parent;
}
Nota 1 O que é perfil, consulte: Aprendam juntos o SF Framework Series 6.2 - módulo core-Environment
BeanDefinitionDocumentReader.parseBeanDefinitions (elemento raiz, delegado BeanDefinitionParserDelegate)
Gere BeanDefinition e registre-o no BeanFactory.
protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {
//根节点是默认命名空间（http://www.springframework.org/schema/beans）解析 注1
if (delegate.isDefaultNamespace(root)) {
//获取根节点下所有子节点
NodeList nl = root.getChildNodes();
//逐一解析每个子节点
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (node instanceof Element ele) {
//每个子节点按命名空间对应解析器进行解析
if (delegate.isDefaultNamespace(ele)) {
parseDefaultElement(ele, delegate);
}
else {
delegate.parseCustomElement(ele);
}
}
}
}
else {
//非默认命名空间解析
delegate.parseCustomElement(root);
}
}
Nota 1: A compreensão do namespace é a seguinte: Um namespace corresponde a um processador de análise:
Se a configuração de anotação estiver habilitada, a linha a seguir precisa ser adicionada ao arquivo de configuração do Spring applicationContext.xml:
<context:annotation-config />
significa a anotação do rótulo -config pertence ao contexto do namespace. contexto corresponde a um processador de análise. Ao analisar, você precisa primeiro obter o processador de análise correspondente ao contexto. O processador de análise inicializará alguns analisadores e um analisador corresponde a uma tag.
Rastreie com base em como o namespace padrão é resolvido.
BeanDefinitionDocumentReader.parseDefaultElement(elemento elemento, delegado BeanDefinitionParserDelegate)
Resolução de elemento para o namespace padrão.
private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {
//<import>标签进入这个方法
if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) {
importBeanDefinitionResource(ele);
}
//<alias>标签进入这个方法
else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) {
processAliasRegistration(ele);
}
//<bean>标签进入这个方法
else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) {
//进入这个方法
processBeanDefinition(ele, delegate);
}
//嵌套标签进入这个方法
else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {
// 嵌套标签从doRegisterBeanDefinitions递归开始
doRegisterBeanDefinitions(ele);
}
}
Rastreie para baixo com base nos beans gerados.
BeanDefinitionDocumentReader.processBeanDefinition(elemento elemento, delegado BeanDefinitionParserDelegate)
Analise o elemento bean em um BeanDefinition e registre-o no BeanFactory.
protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {
//把元素解析成BeanDefinition
BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);
if (bdHolder != null) {
//装饰beanDefinition
bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder);
try {
//注册BeanDefinition到工厂中
BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());
}
catch (BeanDefinitionStoreException ex) {
getReaderContext().error("Failed to register bean definition with name '" +
bdHolder.getBeanName() + "'", ele, ex);
}
// 发送组件(bean)注册事件
getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));
}
}
BeanDefinitionParserDelegate.parseBeanDefinitionElement(elemento elemento)
//Analisa os elementos em BeanDefinition
public BeanDefinitionHolder parseBeanDefinitionElement(Element ele) {
return parseBeanDefinitionElement(ele, null);
}
public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, BeanDefinition containingBean) {
//获取元素id
String id = ele.getAttribute(ID_ATTRIBUTE);
//获取元素name
String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);
//记录元素alias
List<String> aliases = new ArrayList<String>();
/* id、name、alias关系处理 注1 */
//name解析
if (StringUtils.hasLength(nameAttr)) {
//name属性对应的name值如果有分隔符MULTI_VALUE_ATTRIBUTE_DELIMITERS，那么切分成数组
String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS);
//所有name都是别名
aliases.addAll(Arrays.asList(nameArr));
}
//指定了id就用id值作为bean名称
String beanName = id;
//如果没有id，但是指定了name，就用name值作为bean名称
if (!StringUtils.hasText(beanName) && !aliases.isEmpty()) {
//拿第一个name值作为bean名称，其余的还是别名
beanName = aliases.remove(0);
if (logger.isDebugEnabled()) {
logger.debug("No XML 'id' specified - using '" + beanName +
"' as bean name and " + aliases + " as aliases");
}
}
if (containingBean == null) {
//检查bean名称和别名是否已经被使用了，如果用了就报错
checkNameUniqueness(beanName, aliases, ele);
}
//解析beanDefinition本身
AbstractBeanDefinition beanDefinition = parseBeanDefinitionElement(ele, beanName, containingBean);
if (beanDefinition != null) {
//如果没有定义id、name、alias，自动生成beanName
if (!StringUtils.hasText(beanName)) {
try {
//有containingBean
if (containingBean != null) {
beanName = BeanDefinitionReaderUtils.generateBeanName(
beanDefinition, this.readerContext.getRegistry(), true);
}
else {
//无containingBean，用容器生成beanName
beanName = this.readerContext.generateBeanName(beanDefinition);
String beanClassName = beanDefinition.getBeanClassName();
if (beanClassName != null &&
beanName.startsWith(beanClassName) && beanName.length() > beanClassName.length() &&
!this.readerContext.getRegistry().isBeanNameInUse(beanClassName)) {
//beanClassName同时作为别名
aliases.add(beanClassName);
}
}
if (logger.isDebugEnabled()) {
logger.debug("Neither XML 'id' nor 'name' specified - " +
"using generated bean name [" + beanName + "]");
}
}
catch (Exception ex) {
error(ex.getMessage(), ele);
return null;
}
}
String[] aliasesArray = StringUtils.toStringArray(aliases);
//组装成完整beanDefinition返回
return new BeanDefinitionHolder(beanDefinition, beanName, aliasesArray);
}
return null;
}
Nota 1: Para entender os relacionamentos de id, nome e alias dos beans, consulte: Aprenda SF Framework Series 5.1-Module Beans-bean Overview
BeanDefinitionParserDelegate.parseBeanDefinitionElement(Elemento ele, String beanName, @Nullable BeanDefinition contendoBean)
Ele não presta atenção ao nome e alias do bean, mas apenas analisa o próprio BeanDefinition.
public AbstractBeanDefinition parseBeanDefinitionElement(
Element ele, String beanName, BeanDefinition containingBean) {
//解析的beanName进栈（主要考虑元素ele可能还嵌套有子元素，则后续放入子元素，到时子元素先弹出
this.parseState.push(new BeanEntry(beanName));
String className = null;
if (ele.hasAttribute(CLASS_ATTRIBUTE)) {
//如果有指定class属性，则拿到class属性值
className = ele.getAttribute(CLASS_ATTRIBUTE).trim();
}
String parent = null;
if (ele.hasAttribute(PARENT_ATTRIBUTE)) {
//如果有指定parent属性，则拿到parent属性值
parent = ele.getAttribute(PARENT_ATTRIBUTE);
}
try {
//创建BeanDefinition
AbstractBeanDefinition bd = createBeanDefinition(className, parent);
//设置BeanDefinition属性
parseBeanDefinitionAttributes(ele, beanName, containingBean, bd);
//如果有description子元素，设置到BeanDefinition中
bd.setDescription(DomUtils.getChildElementValueByTagName(ele, DESCRIPTION_ELEMENT));
//如果有Meta子元素，获取key和value属性，设置到BeanDefinition中
parseMetaElements(ele, bd);
//如果有lookup-method子元素，获取name和bean属性，设置到BeanDefinition中
parseLookupOverrideSubElements(ele, bd.getMethodOverrides());
//如果有replaced-method子元素，设置BeanDefinition
parseReplacedMethodSubElements(ele, bd.getMethodOverrides());
//如果有constructor-arg子元素，设置BeanDefinition的构造方式
parseConstructorArgElements(ele, bd);
//解析bean的Property的属性设置到BeanDefinition中
parsePropertyElements(ele, bd);
//子元素qualifier处理
parseQualifierElements(ele, bd);
//设置定义来源
bd.setResource(this.readerContext.getResource());
//元素有Source
bd.setSource(extractSource(ele));
return bd;
}
catch (ClassNotFoundException ex) {
error("Bean class [" + className + "] not found", ele, ex);
}
catch (NoClassDefFoundError err) {
error("Class that bean class [" + className + "] depends on not found", ele, err);
}
catch (Throwable ex) {
error("Unexpected failure during bean definition parsing", ele, ex);
}
finally {
//解析完成出栈
this.parseState.pop();
}
return null;
}
BeanDefinitionParserDelegate.createBeanDefinition(@Nullable String className, @Nullable String parentName)
Crie BeanDefinition e defina as propriedades: parentName e beanClassName
protected AbstractBeanDefinition createBeanDefinition(String className, String parentName)
throws ClassNotFoundException {
return BeanDefinitionReaderUtils.createBeanDefinition(
parentName, className, this.readerContext.getBeanClassLoader());
}
/**
* 此方法是BeanDefinitionReaderUtils的静态方法
*/
public static AbstractBeanDefinition createBeanDefinition(
String parentName, String className, ClassLoader classLoader) throws ClassNotFoundException {
//new通用BeanDefinition
GenericBeanDefinition bd = new GenericBeanDefinition();
bd.setParentName(parentName);
if (className != null) {
if (classLoader != null) {
//有classLoader，就导入Class
bd.setBeanClass(ClassUtils.forName(className, classLoader));
}
else {
//无classLoader，只设置BeanClassName
bd.setBeanClassName(className);
}
}
return bd;
}
BeanDefinitionParserDelegate.parseBeanDefinitionAttributes(Elemento ele, String beanName, @Nullable BeanDefinition contendoBean, AbstractBeanDefinition bd)
Analisar configurações de definição de bean em propriedades BeanDefinition
public AbstractBeanDefinition parseBeanDefinitionAttributes(Element ele, String beanName,
BeanDefinition containingBean, AbstractBeanDefinition bd) {
//有singleton属性报错（新的用scope代替）
if (ele.hasAttribute(SINGLETON_ATTRIBUTE)) {
error("Old 1.x 'singleton' attribute in use - upgrade to 'scope' declaration", ele);
}
//如果有scope配置
else if (ele.hasAttribute(SCOPE_ATTRIBUTE)) {
bd.setScope(ele.getAttribute(SCOPE_ATTRIBUTE));
}
else if (containingBean != null) {
// 按containingBean的Scope设置
bd.setScope(containingBean.getScope());
}
//是否有abstract属性
if (ele.hasAttribute(ABSTRACT_ATTRIBUTE)) {
bd.setAbstract(TRUE_VALUE.equals(ele.getAttribute(ABSTRACT_ATTRIBUTE)));
}
//设置lazyInit属性（如果没有设置则为默认值）
String lazyInit = ele.getAttribute(LAZY_INIT_ATTRIBUTE);
if (DEFAULT_VALUE.equals(lazyInit)) {
lazyInit = this.defaults.getLazyInit();
}
bd.setLazyInit(TRUE_VALUE.equals(lazyInit)); //非TRUE_VALUE则为false
//设置autowire属性
String autowire = ele.getAttribute(AUTOWIRE_ATTRIBUTE);
bd.setAutowireMode(getAutowireMode(autowire));
//设置依赖检查属性
String dependencyCheck = ele.getAttribute(DEPENDENCY_CHECK_ATTRIBUTE);
bd.setDependencyCheck(getDependencyCheck(dependencyCheck));
//设置depends-on属性
if (ele.hasAttribute(DEPENDS_ON_ATTRIBUTE)) {
String dependsOn = ele.getAttribute(DEPENDS_ON_ATTRIBUTE);
bd.setDependsOn(StringUtils.tokenizeToStringArray(dependsOn, MULTI_VALUE_ATTRIBUTE_DELIMITERS));
}
//设置autowire-candidate属性
String autowireCandidate = ele.getAttribute(AUTOWIRE_CANDIDATE_ATTRIBUTE);
if ("".equals(autowireCandidate) || DEFAULT_VALUE.equals(autowireCandidate)) {
String candidatePattern = this.defaults.getAutowireCandidates();
if (candidatePattern != null) {
String[] patterns = StringUtils.commaDelimitedListToStringArray(candidatePattern);
bd.setAutowireCandidate(PatternMatchUtils.simpleMatch(patterns, beanName));
}
}
else {
bd.setAutowireCandidate(TRUE_VALUE.equals(autowireCandidate));
}
//设置primary属性
if (ele.hasAttribute(PRIMARY_ATTRIBUTE)) {
bd.setPrimary(TRUE_VALUE.equals(ele.getAttribute(PRIMARY_ATTRIBUTE)));
}
//设置init-method属性
if (ele.hasAttribute(INIT_METHOD_ATTRIBUTE)) {
String initMethodName = ele.getAttribute(INIT_METHOD_ATTRIBUTE);
if (!"".equals(initMethodName)) {
bd.setInitMethodName(initMethodName);
}
}
else {
//没有init-method属性，设置默认InitMethod
if (this.defaults.getInitMethod() != null) {
bd.setInitMethodName(this.defaults.getInitMethod());
bd.setEnforceInitMethod(false);
}
}
//设置destroy-method属性
if (ele.hasAttribute(DESTROY_METHOD_ATTRIBUTE)) {
String destroyMethodName = ele.getAttribute(DESTROY_METHOD_ATTRIBUTE);
bd.setDestroyMethodName(destroyMethodName);
}
else {
//没有destroy-method属性，设置默认DestroyMethod
if (this.defaults.getDestroyMethod() != null) {
bd.setDestroyMethodName(this.defaults.getDestroyMethod());
bd.setEnforceDestroyMethod(false);
}
}
//设置factory-method属性
if (ele.hasAttribute(FACTORY_METHOD_ATTRIBUTE)) {
bd.setFactoryMethodName(ele.getAttribute(FACTORY_METHOD_ATTRIBUTE));
}
//设置factory-bean属性
if (ele.hasAttribute(FACTORY_BEAN_ATTRIBUTE)) {
bd.setFactoryBeanName(ele.getAttribute(FACTORY_BEAN_ATTRIBUTE));
}
return bd;
}
BeanDefinitionParserDelegate.parsePropertyElements(Elemento beanEle, BeanDefinition bd)
Analise o valor da propriedade do bean.
public void parsePropertyElements(Element beanEle, BeanDefinition bd) {
NodeList nl = beanEle.getChildNodes();
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (isCandidateElement(node) && nodeNameEquals(node, PROPERTY_ELEMENT)) {
//元素为PROPERTY_ELEMENT才处理
parsePropertyElement((Element) node, bd);
}
}
}
public void parsePropertyElement(Element ele, BeanDefinition bd) {
//property标签的name属性
String propertyName = ele.getAttribute(NAME_ATTRIBUTE);
if (!StringUtils.hasLength(propertyName)) {
error("Tag 'property' must have a 'name' attribute", ele);
return;
}
//解析property元素进栈
this.parseState.push(new PropertyEntry(propertyName));
try {
//propertyName不能重复name
if (bd.getPropertyValues().contains(propertyName)) {
error("Multiple 'property' definitions for property '" + propertyName + "'", ele);
return;
}
//具体解析property元素属性
Object val = parsePropertyValue(ele, bd, propertyName);
//生成PropertyValue（propertyName:value)
PropertyValue pv = new PropertyValue(propertyName, val);
//ele有meta子元素，获取meta的key和value属性，设置到PropertyValue中
parseMetaElements(ele, pv);
pv.setSource(extractSource(ele));
//将PropertyValue添加到BeanDefinition中
bd.getPropertyValues().addPropertyValue(pv);
}
finally {
//解析property元素出栈
this.parseState.pop();
}
}
public Object parsePropertyValue(Element ele, BeanDefinition bd, String propertyName) {
//如果propertyName为null，则是constructor-arg元素
String elementName = (propertyName != null) ?
"<property> element for property '" + propertyName + "'" :
"<constructor-arg> element";
//Property下面都应该只有一个子标签: ref, value, list等.
NodeList nl = ele.getChildNodes();
Element subElement = null;
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
if (node instanceof Element && !nodeNameEquals(node, DESCRIPTION_ELEMENT) &&
!nodeNameEquals(node, META_ELEMENT)) {
//除开description和meta标签，子标签最多只能有一个
if (subElement != null) {
error(elementName + " must not contain more than one sub-element", ele);
}
else {
subElement = (Element) node;
}
}
}
//元素属性类型ref、value
boolean hasRefAttribute = ele.hasAttribute(REF_ATTRIBUTE);
boolean hasValueAttribute = ele.hasAttribute(VALUE_ATTRIBUTE);
//value和ref属性不能同时存在；如果有子元素，则value和ref都不能存在，否则报错
if ((hasRefAttribute && hasValueAttribute) ||
((hasRefAttribute || hasValueAttribute) && subElement != null)) {
error(elementName +
" is only allowed to contain either 'ref' attribute OR 'value' attribute OR sub-element", ele);
}
//元素属性是ref的情况
if (hasRefAttribute) {
String refName = ele.getAttribute(REF_ATTRIBUTE);
if (!StringUtils.hasText(refName)) {
error(elementName + " contains empty 'ref' attribute", ele);
}
//RuntimeBeanReference是ref的不可变占位符类，实际在运行时解析为真正的bean引用实例
RuntimeBeanReference ref = new RuntimeBeanReference(refName);
ref.setSource(extractSource(ele));
return ref;
}
//元素属性是value的情况
else if (hasValueAttribute) {
//valueHolder存储String值和目标类型。实际的转换将由BeanFactory执行
TypedStringValue valueHolder = new TypedStringValue(ele.getAttribute(VALUE_ATTRIBUTE));
valueHolder.setSource(extractSource(ele));
return valueHolder;
}
else if (subElement != null) {
//子元素处理
return parsePropertySubElement(subElement, bd);
}
else {
//没指定ref或者value或者子元素，返回null
error(elementName + " must specify a ref or value", ele);
return null;
}
}
//过渡方法
public Object parsePropertySubElement(Element ele, BeanDefinition bd) {
return parsePropertySubElement(ele, bd, null);
}
//解析property或者constructor-arg标签的子标签，可能为value, ref或者集合
public Object parsePropertySubElement(Element ele, BeanDefinition bd, String defaultValueType) {
//如果ele不属于默认命名空间
if (!isDefaultNamespace(ele)) {
return parseNestedCustomElement(ele, bd);
}
else if (nodeNameEquals(ele, BEAN_ELEMENT)) {
//如果ele是bean类型，嵌套bean处理
BeanDefinitionHolder nestedBd = parseBeanDefinitionElement(ele, bd);
if (nestedBd != null) {
nestedBd = decorateBeanDefinitionIfRequired(ele, nestedBd, bd);
}
return nestedBd;
}
else if (nodeNameEquals(ele, REF_ELEMENT)) {
//如果ele是ref元素类型
String refName = ele.getAttribute(BEAN_REF_ATTRIBUTE);
boolean toParent = false;
if (!StringUtils.hasLength(refName)) {
// A reference to the id of another bean in a parent context.
//是对父容器中另一个bean id的引用
refName = ele.getAttribute(PARENT_REF_ATTRIBUTE);
toParent = true;
if (!StringUtils.hasLength(refName)) {
error("'bean' or 'parent' is required for <ref> element", ele);
return null;
}
}
if (!StringUtils.hasText(refName)) {
error("<ref> element contains empty target attribute", ele);
return null;
}
//生成引用占位类
RuntimeBeanReference ref = new RuntimeBeanReference(refName, toParent);
ref.setSource(extractSource(ele));
return ref;
}
else if (nodeNameEquals(ele, IDREF_ELEMENT)) {
//如果是idref引用
return parseIdRefElement(ele);
}
else if (nodeNameEquals(ele, VALUE_ELEMENT)) {
//如果是value元素
return parseValueElement(ele, defaultValueType);
}
else if (nodeNameEquals(ele, NULL_ELEMENT)) {
//如果是null元素，用null做值处理
TypedStringValue nullHolder = new TypedStringValue(null);
nullHolder.setSource(extractSource(ele));
return nullHolder;
}
else if (nodeNameEquals(ele, ARRAY_ELEMENT)) {
//如果是array元素
return parseArrayElement(ele, bd);
}
else if (nodeNameEquals(ele, LIST_ELEMENT)) {
//如果是list元素
return parseListElement(ele, bd);
}
else if (nodeNameEquals(ele, SET_ELEMENT)) {
//如果是set元素
return parseSetElement(ele, bd);
}
else if (nodeNameEquals(ele, MAP_ELEMENT)) {
//如果是map元素
return parseMapElement(ele, bd);
}
else if (nodeNameEquals(ele, PROPS_ELEMENT)) {
//如果是props元素
return parsePropsElement(ele);
}
else {
//以上都不是，报错
error("Unknown property sub-element: [" + ele.getNodeName() + "]", ele);
return null;
}
}
A análise de cada tipo de elemento é simples e nenhum rastreamento adicional é necessário.
BeanDefinitionParserDelegate.decorateBeanDefinitionIfRequired (elemento elemento, BeanDefinitionHolder originalDef)
Decore o BeanDefinition conforme necessário.
//过渡方法
public BeanDefinitionHolder decorateBeanDefinitionIfRequired(Element ele, BeanDefinitionHolder definitionHolder) {
return decorateBeanDefinitionIfRequired(ele, definitionHolder, null);
}
//真正装饰BeanDefinition实现
public BeanDefinitionHolder decorateBeanDefinitionIfRequired(
Element ele, BeanDefinitionHolder definitionHolder, BeanDefinition containingBd) {
BeanDefinitionHolder finalDefinition = definitionHolder;
// Decorate based on custom attributes first.
// 基于属性进行
NamedNodeMap attributes = ele.getAttributes();
for (int i = 0; i < attributes.getLength(); i++) {
Node node = attributes.item(i);
finalDefinition = decorateIfRequired(node, finalDefinition, containingBd);
}
// Decorate based on custom nested elements.
// 基于嵌套元素进行
NodeList children = ele.getChildNodes();
for (int i = 0; i < children.getLength(); i++) {
Node node = children.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE) {
finalDefinition = decorateIfRequired(node, finalDefinition, containingBd);
}
}
return finalDefinition;
}
//装饰处理
public BeanDefinitionHolder decorateIfRequired(
Node node, BeanDefinitionHolder originalDef, @Nullable BeanDefinition containingBd) {
String namespaceUri = getNamespaceURI(node);
/*显然，默认命名空间的是不需要装饰的；值装饰非默认命名空间的bean*/
if (namespaceUri != null && !isDefaultNamespace(namespaceUri)) {
//获取非默认命名空间的处理器
NamespaceHandler handler = this.readerContext.getNamespaceHandlerResolver().resolve(namespaceUri);
if (handler != null) {
//装饰处理
BeanDefinitionHolder decorated =
handler.decorate(node, originalDef, new ParserContext(this.readerContext, this, containingBd));
if (decorated != null) {
return decorated;
}
}
else if (namespaceUri.startsWith("http://www.springframework.org/schema/")) {
error("Unable to locate Spring NamespaceHandler for XML schema namespace [" + namespaceUri + "]", node);
}
else {
// A custom namespace, not to be handled by Spring - maybe "xml:...".
if (logger.isDebugEnabled()) {
logger.debug("No Spring NamespaceHandler found for XML schema namespace [" + namespaceUri + "]");
}
}
}
return originalDef;
}
BeanDefinitionReaderUtils.registerBeanDefinition(BeanDefinitionHolder definiçãoHolder, registro BeanDefinitionRegistry)
Registre o BeanDefinition no BeanFactory do contêiner
public static void registerBeanDefinition(
BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry)
throws BeanDefinitionStoreException {
// 用beanName 注册 BeanDefinition
String beanName = definitionHolder.getBeanName();
registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());
//注册别名
String[] aliases = definitionHolder.getAliases();
if (aliases != null) {
for (String alias : aliases) {
registry.registerAlias(beanName, alias);
}
}
}
Nota: o registro é na verdade BeanFactory, Registry.registerBeanDefinition e Registry.registerAlias são implementados em DefaultListableBeanFactory, que é relativamente simples e não será mais rastreado.
Neste ponto, como analisar e rastrear BeanDefinition está concluído. Para saber como usá-lo, consulte: Aprenda o uso do SF Framework Series 5.7-Module Beans-BeanDefinition.