招远做网站联系电话,桂林紧急通知,装修之家网,东莞厚街镇属于哪个区1.XML验证模式的认识 首先XML的验证模式有两种#xff1a;DTD和XSD。
DTD文档类型定义#xff0c;是XML约束模式语言。它是为了保证XML文档格式正确有效的方法。通过XML文档和DTD文档的比较来判断XML是否符合规范。(现在我很少见#xff0c;不知道是不是淘汰了)
举个例子DTD和XSD。
DTD文档类型定义是XML约束模式语言。它是为了保证XML文档格式正确有效的方法。通过XML文档和DTD文档的比较来判断XML是否符合规范。(现在我很少见不知道是不是淘汰了)
举个例子
?xml version1.0 encodingUTF-8?
!DOCTYPE beans PUBLIC -//Spring//DTD BEAN 2.0//ENhttp://www.Springframework.org/dtd/Spring-beans-2.0.dtd
beans
...
/beansXSDXML Schemas Definition它描述了XML文档的结构和规范可以指定一个XML文档允许的结构和内容通过这样就可以校验某一个XML文档是否有效。(这种现在最常见)
举个例子
?xml version1.0 encodingUTF-8?
beans xmlnshttp://www.springframework.org/schema/beansxmlns:xsihttp://www.w3.org/2001/XMLSchema-instancexmlns:contexthttp://www.springframework.org/schema/contextxmlns:mvchttp://www.springframework.org/schema/mvcxsi:schemaLocationhttp://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvchttp://www.springframework.org/schema/mvc/spring-mvc.xsd上面的http://www.springframework.org/schema/beans/spring-beans.xsd这个命名空间就指定了xml中bean的验证方式。 具体的校验我就不介绍了每一个命名空间都可以查看对应的校验内容 。
2.通过ClassPathXmlApplicationContext来认识spring 下面以我们刚接触spring时通过ClassPathXmlApplicationContext获取bean的方式来认识spring源码。
?xml version1.0 encodingUTF-8?
beans xmlnshttp://www.springframework.org/schema/beansxmlns:xsihttp://www.w3.org/2001/XMLSchema-instance xmlns:phttp://www.springframework.org/schema/pxmlns:contexthttp://www.springframework.org/schema/contextxmlns:mvchttp://www.springframework.org/schema/mvcxsi:schemaLocationhttp://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/mvchttp://www.springframework.org/schema/mvc/spring-mvc.xsdbean iduser classsupport.mode.Userproperty nameuseId value00232/propertyproperty nameuserName valuetopsnowwolf//bean/beanspublic static void main(String[] args) {ApplicationContext applicationContext new ClassPathXmlApplicationContext(spring-mvc.xml);User user applicationContext.getBean(User.class);System.out.println(user.getUseId():user.getUserName());}认识前先了解类,接口的关系 现在我们初步认识一下下面这几个对象
BeanFactory:定义获取bean以及bean的各种属性。 ListableBeanFactory根据各种条件获取bean的配置清单。 ResourceLoader资源加载器 AbstractApplicationContext这个抽象类的refresh方法为是解析xml,获取,加载bean的入口。 在实例化ClassPathXmlApplicationContext对象时会调用ClassPathXmlApplicationContext的构造方法创建对象在创建
ClassPathXmlApplicationContext时就会进行一系列的操作。
经过分析入口就是AbstractApplicationContext类的refresh方法。
public void refresh() throws BeansException, IllegalStateException {Object var1 this.startupShutdownMonitor;synchronized(this.startupShutdownMonitor) {this.prepareRefresh();ConfigurableListableBeanFactory beanFactory this.obtainFreshBeanFactory();//获取BeanFactory配置清单this.prepareBeanFactory(beanFactory);try {this.postProcessBeanFactory(beanFactory);this.invokeBeanFactoryPostProcessors(beanFactory);this.registerBeanPostProcessors(beanFactory);this.initMessageSource();this.initApplicationEventMulticaster();this.onRefresh();this.registerListeners();this.finishBeanFactoryInitialization(beanFactory);this.finishRefresh();} catch (BeansException var9) {if (this.logger.isWarnEnabled()) {this.logger.warn(Exception encountered during context initialization - cancelling refresh attempt: var9);}this.destroyBeans();this.cancelRefresh(var9);throw var9;} finally {this.resetCommonCaches();}}}ConfigurableListableBeanFactory对象的创建。
ConfigurableListableBeanFactory是BeanFactory配置清单。
ConfigurableListableBeanFactory和DefaultListableBeanFactory的关系图。 获取BeanFactory配置清单
通过obtainFreshBeanFactory()方法
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {this.refreshBeanFactory();//获取DefaultListableBeanFactory对象。ConfigurableListableBeanFactory beanFactory this.getBeanFactory();if (this.logger.isDebugEnabled()) {this.logger.debug(Bean factory for this.getDisplayName() : beanFactory);}return beanFactory;}refreshBeanFactory方法的认识 由于AbstractApplicationContext类的refreshBeanFactory方法是抽象方法实现类是AbstractRefreshableApplicationContext。
关系图 protected abstract void refreshBeanFactory() throws BeansException, IllegalStateException;protected final void refreshBeanFactory() throws BeansException {if (this.hasBeanFactory()) {this.destroyBeans();this.closeBeanFactory();}try {DefaultListableBeanFactory beanFactory this.createBeanFactory();beanFactory.setSerializationId(this.getId());//给DefaultListableBeanFactory设置序列化IDthis.customizeBeanFactory(beanFactory);//当我们配置了两个name属性相同的Bean时spring默认会后面配置的Bean会覆盖掉前面配置的Bean对象this.loadBeanDefinitions(beanFactory);//Object var2 this.beanFactoryMonitor;synchronized(this.beanFactoryMonitor) {this.beanFactory beanFactory;}} catch (IOException var5) {throw new ApplicationContextException(I/O error parsing bean definition source for this.getDisplayName(), var5);}}AbstractRefreshableApplicationContext的方法loadBeanDefinitions实现由AbstractXmlApplicationContext。关系图 protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException {XmlBeanDefinitionReader beanDefinitionReader new XmlBeanDefinitionReader(beanFactory);beanDefinitionReader.setEnvironment(this.getEnvironment());beanDefinitionReader.setResourceLoader(this);beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));this.initBeanDefinitionReader(beanDefinitionReader);this.loadBeanDefinitions(beanDefinitionReader);}最后loadBeanDefinitions这方法绕来绕去会调用到XmlBeanDefinitionReader中的loadBeanDefinitions方法。 到现在还没真正的解析XML之前的工作全部是准备。是不是很绕啊。
3.Spring解析XML成document的过程 XmlBeanDefinitionReader类中的loadBeanDefinitions就是重点了
大概思路
xml等配置会被注册到容器中xml文件最终都会通过ResourceLoader加重成Resource对象通Reader进行解析读取最后注册到容器中spring以sax的方式解析xml。
public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {Assert.notNull(encodedResource, EncodedResource must not be null);if (this.logger.isInfoEnabled()) {this.logger.info(Loading XML bean definitions from encodedResource.getResource());}SetEncodedResource currentResources (Set)this.resourcesCurrentlyBeingLoaded.get();if (currentResources null) {currentResources new HashSet(4);this.resourcesCurrentlyBeingLoaded.set(currentResources);}if (!((Set)currentResources).add(encodedResource)) {throw new BeanDefinitionStoreException(Detected cyclic loading of encodedResource - check your import definitions!);} else {int var5;try {InputStream inputStream encodedResource.getResource().getInputStream();try {InputSource inputSource new InputSource(inputStream);if (encodedResource.getEncoding() ! null) {inputSource.setEncoding(encodedResource.getEncoding());}var5 this.doLoadBeanDefinitions(inputSource, encodedResource.getResource());} finally {inputStream.close();}} catch (IOException var15) {throw new BeanDefinitionStoreException(IOException parsing XML document from encodedResource.getResource(), var15);} finally {((Set)currentResources).remove(encodedResource);if (((Set)currentResources).isEmpty()) {this.resourcesCurrentlyBeingLoaded.remove();}}return var5;}}第一步
XmlBeanDefinitionReader类的loadBeanDefinitions(Resource resource)方法将Resource对象封装成EncodedResource对象。EncodedResource的作用是对资源文件进行编码格式处理处理方法看EncodedResource类的getReader()
public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException {return this.loadBeanDefinitions(new EncodedResource(resource));}public class EncodedResource implements InputStreamSource {private final Resource resource;private final String encoding;private final Charset charset;public EncodedResource(Resource resource) {this(resource, (String)null, (Charset)null);}public EncodedResource(Resource resource, String encoding) {this(resource, encoding, (Charset)null);}public EncodedResource(Resource resource, Charset charset) {this(resource, (String)null, charset);}private EncodedResource(Resource resource, String encoding, Charset charset) {Assert.notNull(resource, Resource must not be null);this.resource resource;this.encoding encoding;this.charset charset;}
....第二步
从EncodedResource中获取InputStream 之后将InputStream 转化为InputSource。
public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException {Assert.notNull(encodedResource, EncodedResource must not be null);if (this.logger.isInfoEnabled()) {this.logger.info(Loading XML bean definitions from encodedResource.getResource());}SetEncodedResource currentResources (Set)this.resourcesCurrentlyBeingLoaded.get();//通过属性来记录已经加载的资源。if (currentResources null) {currentResources new HashSet(4);this.resourcesCurrentlyBeingLoaded.set(currentResources);}if (!((Set)currentResources).add(encodedResource)) {throw new BeanDefinitionStoreException(Detected cyclic loading of encodedResource - check your import definitions!);} else {int var5;try {InputStream inputStream encodedResource.getResource().getInputStream();//从EncodedResource中获取InputStream 。try {InputSource inputSource new InputSource(inputStream);//将InputStream 转化为InputSource为何要转化为InputSource呢?下面解析xml时再解释。if (encodedResource.getEncoding() ! null) {//设置编码格式inputSource.setEncoding(encodedResource.getEncoding());//}var5 this.doLoadBeanDefinitions(inputSource, encodedResource.getResource());//进入解析XML的核心代码} finally {inputStream.close();}} catch (IOException var15) {throw new BeanDefinitionStoreException(IOException parsing XML document from encodedResource.getResource(), var15);} finally {((Set)currentResources).remove(encodedResource);if (((Set)currentResources).isEmpty()) {this.resourcesCurrentlyBeingLoaded.remove();}}return var5;}}第三步
进入解析XML(小知识 xml的解析方式jdk的提供的dom解析dom4j,sax常用的三种。)
由于spring对xml的解释是采用sax方式进行解析的所以现在大概知道为什么要将InputStream 转化为InputSource了吧。因为sax解析xml时parse方法入参就必须是sax提供的InputSource流对象。
this.doLoadBeanDefinitions(inputSource, encodedResource.getResource());//进入解析XML的核心代码protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource) throws BeanDefinitionStoreException {try {Document doc this.doLoadDocument(inputSource, resource);//sax方式解释xmlreturn this.registerBeanDefinitions(doc, resource);//注册bean} catch (BeanDefinitionStoreException var4) {throw var4;} catch (SAXParseException var5) {throw new XmlBeanDefinitionStoreException(resource.getDescription(), Line var5.getLineNumber() in XML document from resource is invalid, var5);} catch (SAXException var6) {throw new XmlBeanDefinitionStoreException(resource.getDescription(), XML document from resource is invalid, var6);} catch (ParserConfigurationException var7) {throw new BeanDefinitionStoreException(resource.getDescription(), Parser configuration exception parsing XML from resource, var7);} catch (IOException var8) {throw new BeanDefinitionStoreException(resource.getDescription(), IOException parsing XML document from resource, var8);} catch (Throwable var9) {throw new BeanDefinitionStoreException(resource.getDescription(), Unexpected exception parsing XML document from resource, var9);}}初略说一下doLoadDocument
protected Document doLoadDocument(InputSource inputSource, Resource resource) throws Exception {return this.documentLoader.loadDocument(inputSource, this.getEntityResolver(), //向SAX 驱动器注册一个实例EntityResolver至于为何要一定要这个EntityResolver这个实例给SAX就不多说了。this.errorHandler, //SimpleSaxErrorHandler对象this.getValidationModeForResource(resource), //XML验证方式的读取this.isNamespaceAware() //);}protected int getValidationModeForResource(Resource resource) {int validationModeToUse this.getValidationMode();if (validationModeToUse ! VALIDATION_AUTO) {//如果手动指定了验证模式则使用指定的验证模式return validationModeToUse;} else {//没有自动检测int detectedMode this.detectValidationMode(resource);return detectedMode ! VALIDATION_AUTO ? detectedMode : VALIDATION_XSD;}}调用DefaultDocumentLoader类中的loadDocument解析xml
public Document loadDocument(InputSource inputSource, EntityResolver entityResolver, ErrorHandler errorHandler, int validationMode, boolean namespaceAware) throws Exception {DocumentBuilderFactory factory this.createDocumentBuilderFactory(validationMode, namespaceAware);//创建一个工厂工厂模式if (logger.isDebugEnabled()) {logger.debug(Using JAXP provider [ factory.getClass().getName() ]);}DocumentBuilder builder this.createDocumentBuilder(factory, entityResolver, errorHandler);//获取建造者建造者模式return builder.parse(inputSource);//解释XML成Document}sax如何解析xml成Document这里就不废话了。
第四步
将解析的document对应的bean注册到spring容器中。
public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {BeanDefinitionDocumentReader documentReader this.createBeanDefinitionDocumentReader();//实例化BeanDefinitionDocumentReaderint countBefore this.getRegistry().getBeanDefinitionCount();//总结已经存在的BeanDefinition个数documentReader.registerBeanDefinitions(doc, this.createReaderContext(resource));//加载注册bean 核心return this.getRegistry().getBeanDefinitionCount() - countBefore;//返回本次加载的BeanDefinition个数}这里就是最最最核心的代码了。 BeanDefinitionDocumentReader是一个接口而实例化由createBeanDefinitionDocumentReader()完成 protected BeanDefinitionDocumentReader createBeanDefinitionDocumentReader() {return (BeanDefinitionDocumentReader)BeanDefinitionDocumentReader.class.cast(BeanUtils.instantiateClass(this.documentReaderClass));}通过这个可以知道BeanDefinitionDocumentReader的实现类是DefaultBeanDefinitionDocumentReader。 下面我们重点看一下DefaultBeanDefinitionDocumentReader类中的registerBeanDefinitions()方法。 public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {this.readerContext readerContext;this.logger.debug(Loading bean definitions);Element root doc.getDocumentElement();//获取document的元素。this.doRegisterBeanDefinitions(root);}此时我们才真真正正的看到了底层的实现方法。绕来绕去终于看到了曙光下面我们接着分析doRegisterBeanDefinitionsroot方法。
protected void doRegisterBeanDefinitions(Element root) {BeanDefinitionParserDelegate parent this.delegate;this.delegate this.createDelegate(this.getReaderContext(), root, parent);//实例化BeanDefinitionParserDelegate是一个解析器代理类。if (this.delegate.isDefaultNamespace(root)) {String profileSpec root.getAttribute(profile);//处理profile属性profile来实现动态生成相应的bean如何实现网上很多例子这里就不介绍了。https://www.cnblogs.com/yw0219/p/5990056.htmlhttps://www.jianshu.com/p/948c303b2253这两篇文章介绍得很具体。if (StringUtils.hasText(profileSpec)) {String[] specifiedProfiles StringUtils.tokenizeToStringArray(profileSpec, ,; );if (!this.getReaderContext().getEnvironment().acceptsProfiles(specifiedProfiles)) {return;}}}this.preProcessXml(root);this.parseBeanDefinitions(root, this.delegate);this.postProcessXml(root);this.delegate parent;}此时会发现这里才是真真正正对XML的每一个节点进行解析 大略看一下BeanDefinitionParserDelegate的你发现它实际就是封装了bean的各种属性。
public class BeanDefinitionParserDelegate {public static final String BEANS_NAMESPACE_URI http://www.springframework.org/schema/beans;public static final String MULTI_VALUE_ATTRIBUTE_DELIMITERS ,; ;public static final String TRUE_VALUE true;public static final String FALSE_VALUE false;public static final String DEFAULT_VALUE default;public static final String DESCRIPTION_ELEMENT description;public static final String AUTOWIRE_NO_VALUE no;public static final String AUTOWIRE_BY_NAME_VALUE byName;public static final String AUTOWIRE_BY_TYPE_VALUE byType;public static final String AUTOWIRE_CONSTRUCTOR_VALUE constructor;public static final String AUTOWIRE_AUTODETECT_VALUE autodetect;public static final String DEPENDENCY_CHECK_ALL_ATTRIBUTE_VALUE all;public static final String DEPENDENCY_CHECK_SIMPLE_ATTRIBUTE_VALUE simple;public static final String DEPENDENCY_CHECK_OBJECTS_ATTRIBUTE_VALUE objects;public static final String NAME_ATTRIBUTE name;public static final String BEAN_ELEMENT bean;public static final String META_ELEMENT meta;public static final String ID_ATTRIBUTE id;public static final String PARENT_ATTRIBUTE parent;public static final String CLASS_ATTRIBUTE class;public static final String ABSTRACT_ATTRIBUTE abstract;public static final String SCOPE_ATTRIBUTE scope;private static final String SINGLETON_ATTRIBUTE singleton;public static final String LAZY_INIT_ATTRIBUTE lazy-init;public static final String AUTOWIRE_ATTRIBUTE autowire;public static final String AUTOWIRE_CANDIDATE_ATTRIBUTE autowire-candidate;public static final String PRIMARY_ATTRIBUTE primary;public static final String DEPENDENCY_CHECK_ATTRIBUTE dependency-check;public static final String DEPENDS_ON_ATTRIBUTE depends-on;public static final String INIT_METHOD_ATTRIBUTE init-method;public static final String DESTROY_METHOD_ATTRIBUTE destroy-method;public static final String FACTORY_METHOD_ATTRIBUTE factory-method;public static final String FACTORY_BEAN_ATTRIBUTE factory-bean;public static final String CONSTRUCTOR_ARG_ELEMENT constructor-arg;public static final String INDEX_ATTRIBUTE index;public static final String TYPE_ATTRIBUTE type;public static final String VALUE_TYPE_ATTRIBUTE value-type;public static final String KEY_TYPE_ATTRIBUTE key-type;public static final String PROPERTY_ELEMENT property;public static final String REF_ATTRIBUTE ref;public static final String VALUE_ATTRIBUTE value;public static final String LOOKUP_METHOD_ELEMENT lookup-method;public static final String REPLACED_METHOD_ELEMENT replaced-method;public static final String REPLACER_ATTRIBUTE replacer;public static final String ARG_TYPE_ELEMENT arg-type;public static final String ARG_TYPE_MATCH_ATTRIBUTE match;public static final String REF_ELEMENT ref;public static final String IDREF_ELEMENT idref;public static final String BEAN_REF_ATTRIBUTE bean;public static final String LOCAL_REF_ATTRIBUTE local;public static final String PARENT_REF_ATTRIBUTE parent;public static final String VALUE_ELEMENT value;public static final String NULL_ELEMENT null;public static final String ARRAY_ELEMENT array;public static final String LIST_ELEMENT list;public static final String SET_ELEMENT set;public static final String MAP_ELEMENT map;public static final String ENTRY_ELEMENT entry;public static final String KEY_ELEMENT key;public static final String KEY_ATTRIBUTE key;public static final String KEY_REF_ATTRIBUTE key-ref;public static final String VALUE_REF_ATTRIBUTE value-ref;public static final String PROPS_ELEMENT props;public static final String PROP_ELEMENT prop;public static final String MERGE_ATTRIBUTE merge;public static final String QUALIFIER_ELEMENT qualifier;public static final String QUALIFIER_ATTRIBUTE_ELEMENT attribute;public static final String DEFAULT_LAZY_INIT_ATTRIBUTE default-lazy-init;public static final String DEFAULT_MERGE_ATTRIBUTE default-merge;public static final String DEFAULT_AUTOWIRE_ATTRIBUTE default-autowire;public static final String DEFAULT_DEPENDENCY_CHECK_ATTRIBUTE default-dependency-check;public static final String DEFAULT_AUTOWIRE_CANDIDATES_ATTRIBUTE default-autowire-candidates;public static final String DEFAULT_INIT_METHOD_ATTRIBUTE default-init-method;public static final String DEFAULT_DESTROY_METHOD_ATTRIBUTE default-destroy-method;protected final Log logger LogFactory.getLog(this.getClass());private final XmlReaderContext readerContext;private final DocumentDefaultsDefinition defaults new DocumentDefaultsDefinition();private final ParseState parseState new ParseState();private final SetString usedNames new HashSet();......parseBeanDefinitions()这个方法必须重点认识
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);//解析默认的bean} else {delegate.parseCustomElement(ele);//解析自定义的bean}}}} else {delegate.parseCustomElement(root);}}不同bean的认识
默认的bean:
bean iduser classsupport.mode.Userproperty nameuseId value00232/propertyproperty nameuserName valuetopsnowwolf//bean自定义的bean:
tx:annotation-driven /这两者区别很大如果是spring默认配置的beanspring肯定知道如何处理自定义的就要实现一下接口和配置。 问题spring是如何知道是默认的还是自定义的呢
public boolean isDefaultNamespace(String namespaceUri) {return !StringUtils.hasLength(namespaceUri) || http://www.springframework.org/schema/beans.equals(namespaceUri);}public boolean isDefaultNamespace(Node node) {return this.isDefaultNamespace(this.getNamespaceURI(node));}判断是默认的还是自定义的通过标签对应的命名空间去判断。
当命名空间是http://www.springframework.org/schema/beans时就是默认的。下次我将总结一下如何自定义spring的标签这样就能更好的认识自定义的解析这里就不多说了。不过为了有点了解还是举个例子吧。
?xml version1.0 encodingUTF-8?
beans xmlnshttp://www.springframework.org/schema/beansxmlns:xsihttp://www.w3.org/2001/XMLSchema-instancexmlns:contexthttp://www.springframework.org/schema/context xmlns:txhttp://www.springframework.org/schema/txxmlns:aophttp://www.springframework.org/schema/aopxsi:schemaLocationhttp://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/contexthttp://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/txhttp://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.springframework.org/schema/aophttp://www.springframework.org/schema/aop/spring-aop.xsd!-- 自动扫描 --context:component-scan base-packagesupport.*/tx:annotation-driven /!-- 第一种方式加载一个properties文件 --bean idpropertyConfigurer classorg.springframework.beans.factory.config.PropertyPlaceholderConfigurerproperty namelocation valueclasspath:jdbc.properties//bean上面这一部分配置
我们可以看到 context标签对应的命名空间就是http://www.springframework.org/schema/context。
tx的是http://www.springframework.org/schema/tx。
差不多了
最后总结一下整个过程
