Spring一小部分源码解析（持续）
Posted toov5
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了Spring一小部分源码解析（持续）相关的知识，希望对你有一定的参考价值。
如何查看源码
Spring源码下载https://github.com/spring-projects/spring-framework/tags?after=v3.1.0.RC1
eclipse关联源码 自己百度吧
源代码结构组织
Build-spring-framework是整个Spring源代码的构建目录，里面是项目的构建脚本，如果要自己动手构建Spring，可以进入这个目录使用ANT进行构建。
l org.springframework.context是IoC容器的源代码目录
l org.springframework.aop是AOP实现的源代码目录
l org.springframework.jdbc是JDBC的源代码部分
l org.springframework.orm是O/R Mapping对应的源代码实现部分
SpringIOC源码分析
IOC初始化
1、 XmlBeanFactory(屌丝IOC)的整个流程
2、 FileSystemXmlApplicationContext 的IOC容器流程
1、高富帅IOC解剖
2、 设置资源加载器和资源定位
3、AbstractApplicationContext的refresh函数载入Bean定义过程：
4、AbstractApplicationContext子类的refreshBeanFactory()方法：
5、AbstractRefreshableApplicationContext子类的loadBeanDefinitions方法：
6、AbstractBeanDefinitionReader读取Bean定义资源：
7、资源加载器获取要读入的资源：
8、XmlBeanDefinitionReader加载Bean定义资源：
9、DocumentLoader将Bean定义资源转换为Document对象：
10、XmlBeanDefinitionReader解析载入的Bean定义资源文件：
11、DefaultBeanDefinitionDocumentReader对Bean定义的Document对象解析：
12、BeanDefinitionParserDelegate解析Bean定义资源文件中的<Bean>元素：
13、BeanDefinitionParserDelegate解析<property>元素：
14、解析<property>元素的子元素：
15、解析<list>子元素：
16、解析过后的BeanDefinition在IoC容器中的注册：
17、DefaultListableBeanFactory向IoC容器注册解析后的BeanDefinition：
IOC体系
BeanFactory
Spring Bean的创建是典型的工厂模式，这一系列的Bean工厂，也即IOC容器为开发者管理对象间的依赖关系提供了很多便利和基础服务，在Spring中有许多的IOC容器的实现供用户选择和使用，其相互关系如下：
BeanFactory
BeanFactory定义了 IOC 容器的最基本形式，并提供了 IOC 容器应遵守的的最基本的接口，也就是Spring IOC 所遵守的最底层和最基本的编程规范。在 Spring 代码中， BeanFactory 只是个接口，并不是 IOC容器的具体实现，但是 Spring 容器给出了很多种实现，如 DefaultListableBeanFactory 、 XmlBeanFactory 、ApplicationContext 等，都是附加了某种功能的实现。
大体思路是 反射+DOM4J, 解析配置文件，通过beanId查找bean是否存在
存在的话，获取该节点class地址，使用反射机制初始化。
Spring 使用了很多抽象类
Spring核心jar包：
SpringCore -- Spring 核心jar
SpringContext--上下文IOC具体实现
Spring-Bean -- Spring实例
Spring-jdbc
SpringAOP
BeanFactory接口： ctrl+T
核心方法查看：Bean的工厂
定义接口去进行规范
public interface BeanFactory { //这里是对FactoryBean的转义定义，因为如果使用bean的名字检索FactoryBean得到的对象是工厂生成的对象， //如果需要得到工厂本身，需要转义 //转义符“&”用来获取FactoryBean本身 String FACTORY_BEAN_PREFIX = "&"; //根据bean的名字进行获取bean的实例，这是IOC最大的抽象方法 Object getBean(String name) throws BeansException; //根据bean的名字和Class类型进行获取Bean的实例,和上面方法不同的是，bean名字和Bean 的class类型不同时候会爆出异常 <T> T getBean(String name, Class<T> requiredType) throws BeansException; <T> T getBean(Class<T> requiredType) throws BeansException; Object getBean(String name, Object... args) throws BeansException; //检测这个IOC容器中是否含有这个Bean boolean containsBean(String name); //判断这个Bean是不是单利 boolean isSingleton(String name) throws NoSuchBeanDefinitionException; //判断这个Bean是不是原型 boolean isPrototype(String name) throws NoSuchBeanDefinitionException; //查询指定的bean的名字和Class类型是不是指定的Class类型 boolean isTypeMatch(String name, Class targetType) throws NoSuchBeanDefinitionException; //这里对得到bean实例的Class类型 Class<?> getType(String name) throws NoSuchBeanDefinitionException; //这里得到bean的别名，如果根据别名检索，那么其原名也会被检索出来 String[] getAliases(String name); }
BeanDefinition
这个接口，可以理解为xml bean元素的数据载体。通过对比xml bean标签的属性列表和BeanDefinition的属性列表一看便知。
我的理解，是解析XML的过程，就是 xml <bean>元素内容 转换为BeanDefinition对象的过程。而且这个接口，支持层级，对应对象的继承。
有一个类BeanDefinitionHolder,BeanDefinitionHolder，根据名称或者别名持有beanDefinition，它承载了name和BeanDefinition的映射信息。
BeanWarpper:
提供对标准javabean的分析和操作方法：单个或者批量获取和设置属性值，获取属性描述符，查询属性的可读性和可写性等。支持属性的嵌套设置，深度没有限制。
AbstractRefreshableApplicationContext的refreshBeanFactory()这个方法
核心类：
核心方法：
这个接口主要做xml解析的
封装xml解析Spring Bean文件的解析封装 （可以get出来个Bean属性哈哈）
方法：
一：
/** * Return the current bean class name of this bean definition. * <p>Note that this does not have to be the actual class name used at runtime, in * case of a child definition overriding/inheriting the class name from its parent. * Also, this may just be the class that a factory method is called on, or it may * even be empty in case of a factory bean reference that a method is called on. * Hence, do <i>not</i> consider this to be the definitive bean type at runtime but * rather only use it for parsing purposes at the individual bean definition level. * @see #getParentName() * @see #getFactoryBeanName() * @see #getFactoryMethodName() */ @Nullable String getBeanClassName();
获取bean的class文件地址 id = xx class=“”com.tooc5.car“
二：
/** * Override the target scope of this bean, specifying a new scope name. * @see #SCOPE_SINGLETON * @see #SCOPE_PROTOTYPE */ void setScope(@Nullable String scope);
xml的配置的范围属性
分析看一个类： 分析要分析父类 一直追踪。核心的都封装在父类
点击进入这个抽象类 AbstractRefreshableApplicationContext
看它的方法：refreshBeanFactory()
protected final void refreshBeanFactory() throws BeansException { if (hasBeanFactory()) { destroyBeans(); closeBeanFactory(); } try { DefaultListableBeanFactory beanFactory = createBeanFactory();//创建IOC容器（Bean工厂）！！！！！！ beanFactory.setSerializationId(getId()); customizeBeanFactory(beanFactory); loadBeanDefinitions(beanFactory); //载入loadBeanDefinitions 直接把工厂传入进去了 synchronized (this.beanFactoryMonitor) { this.beanFactory = beanFactory; } } catch (IOException ex) { throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex); } }
点进入看：
loadBeanDefinitions(beanFactory);
实现类：
@Override protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException { // Create a new XmlBeanDefinitionReader for the given BeanFactory. XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory); //读取容器 // Configure the bean definition reader with this context\'s // resource loading environment. beanDefinitionReader.setEnvironment(this.getEnvironment()); beanDefinitionReader.setResourceLoader(this); //获取到当前上下文 beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this)); // Allow a subclass to provide custom initialization of the reader, // then proceed with actually loading the bean definitions. initBeanDefinitionReader(beanDefinitionReader); loadBeanDefinitions(beanDefinitionReader); }
继续点进去看：
loadBeanDefinitions(beanDefinitionReader); 加载配置文件
protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException { Resource[] configResources = getConfigResources(); if (configResources != null) { reader.loadBeanDefinitions(configResources); } String[] configLocations = getConfigLocations(); //数组形式 可以加载多个配置文件 if (configLocations != null) { reader.loadBeanDefinitions(configLocations); } }
持续点击：
reader.loadBeanDefinitions(configLocations);
@Override public int loadBeanDefinitions(String... locations) throws BeanDefinitionStoreException { //可以传递多个路径进入 Assert.notNull(locations, "Location array must not be null"); int count = 0; for (String location : locations) { count += loadBeanDefinitions(location); } return count; }
持续点击：
loadBeanDefinitions(location);
循环读取配置文件
@Override public int loadBeanDefinitions(String location) throws BeanDefinitionStoreException { return loadBeanDefinitions(location, null); }
持续点击：
loadBeanDefinitions(location, null);
/** * Load bean definitions from the specified resource location. * <p>The location can also be a location pattern, provided that the * ResourceLoader of this bean definition reader is a ResourcePatternResolver. * @param location the resource location, to be loaded with the ResourceLoader * (or ResourcePatternResolver) of this bean definition reader * @param actualResources a Set to be filled with the actual Resource objects * that have been resolved during the loading process. May be {@code null} * to indicate that the caller is not interested in those Resource objects. * @return the number of bean definitions found * @throws BeanDefinitionStoreException in case of loading or parsing errors * @see #getResourceLoader() * @see #loadBeanDefinitions(org.springframework.core.io.Resource) * @see #loadBeanDefinitions(org.springframework.core.io.Resource[]) */ public int loadBeanDefinitions(String location, @Nullable Set<Resource> actualResources) throws BeanDefinitionStoreException { ResourceLoader resourceLoader = getResourceLoader(); //获取到当配置路径 if (resourceLoader == null) { throw new BeanDefinitionStoreException( "Cannot load bean definitions from location [" + location + "]: no ResourceLoader available"); } if (resourceLoader instanceof ResourcePatternResolver) { // Resource pattern matching available. try { Resource[] resources = ((ResourcePatternResolver) resourceLoader).getResources(location); int count = loadBeanDefinitions(resources); if (actualResources != null) { Collections.addAll(actualResources, resources); } if (logger.isTraceEnabled()) { logger.trace("Loaded " + count + " bean definitions from location pattern [" + location + "]"); } return count; } catch (IOException ex) { throw new BeanDefinitionStoreException( "Could not resolve bean definition resource pattern [" + location + "]", ex); } } else { //////// 看这里 // Can only load single resources by absolute URL. Resource resource = resourceLoader.getResource(location); //获取资源文件 int count = loadBeanDefinitions(resource); if (actualResources != null) { actualResources.add(resource); } if (logger.isTraceEnabled()) { logger.trace("Loaded " + count + " bean definitions from location [" + location + "]"); } return count; } }
拿到resource后继续读取，点击
int count = loadBeanDefinitions(resource);
点击xml的 不是配置 文件的
/** * Load bean definitions from the specified XML file. * @param resource the resource descriptor for the XML file * @return the number of bean definitions found * @throws BeanDefinitionStoreException in case of loading or parsing errors */ @Override public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException { return loadBeanDefinitions(new EncodedResource(resource)); }
持续点击：
return loadBeanDefinitions(new EncodedResource(resource));
/** * Load bean definitions from the specified XML file. * @param encodedResource the resource descriptor for the XML file, * allowing to specify an encoding to use for parsing the file * @return the number of bean definitions found * @throws BeanDefinitionStoreException in case of loading or parsing errors */ public int loadBeanDefinitions(EncodedResource encodedResource) throws BeanDefinitionStoreException { Assert.notNull(encodedResource, "EncodedResource must not be null"); if (logger.isTraceEnabled()) { logger.trace("Loading XML bean definitions from " + encodedResource); } Set<EncodedResource> 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 { InputStream inputStream = encodedResource.getResource().getInputStream(); //拿到input流 try { InputSource inputSource = new InputSource(inputStream); //读取input流 if (encodedResource.getEncoding() != null) { inputSource.setEncoding(encodedResource.getEncoding()); //进行转码 } 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(); } } }
拿到文件流之后？ 持续点击
return doLoadBeanDefinitions(inputSource, encodedResource.getResource());
protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource) throws BeanDefinitionStoreException { try { //XML的DOM4J解析 Document doc = doLoadDocument(inputSource, resource); 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); } }
如何解析的？持续点击：
/** * Actually load bean definitions from the specified XML file. * @param inputSource the SAX InputSource to read from * @param resource the resource descriptor for the XML file * @return the number of bean definitions found * @throws BeanDefinitionStoreException in case of loading or parsing errors * @see #doLoadDocument * @see #registerBeanDefinitions */ protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource) throws BeanDefinitionStoreException { try { Document doc = doLoadDocument(inputSource, resource); //解析出doc int count = registerBeanDefinitions(doc, resource); //注册bean 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); } }
拿到：doc 和 resource后，注册bean：持续点击
int count = registerBeanDefinitions(doc, resource);
public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException { BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader(); int countBefore = getRegistry().getBeanDefinitionCount(); documentReader.registerBeanDefinitions(doc, createReaderContext(resource)); // 作bean的注册 return getRegistry().getBeanDefinitionCount() - countBefore; }
持续点击：
documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
@Override public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) { this.readerContext = readerContext; doRegisterBeanDefinitions(doc.getDocumentElement()); }
继续点击进入： 从根目录获取到配置文件document。拿到根路径后正式做解析。
/** * Register each bean definition within the given root {@code <beans/>} element. */ @SuppressWarnings("deprecation") // for Environment.acceptsProfiles(String...) protected void doRegisterBeanDefinitions(Element root) { // Any nested <beans> elements will cause recursion in this method. In // order to propagate and preserve <beans> default-* attributes correctly, // keep track of the current (parent) delegate, which may be null. Create // the new (child) delegate with a reference to the parent for fallback purposes, // then ultimately reset this.delegate back to its original (parent) reference. // this behavior emulates a stack of delegates without actually necessitating one. BeanDefinitionParserDelegate parent = this.delegate; this.delegate = createDelegate(getReaderContext(), root, parent); 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); // 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; } } } preProcessXml(root); parseBeanDefinitions(root, this.delegate); //做documet解析 postProcessXml(root); this.delegate = parent; }
持续点击：
parseBeanDefinitions(root, this.delegate); //做documet解析 从根路径开始解析 遍历节点
/** * Parse the elements at the root level in the document: * "import", "alias", "bean". * @param root the DOM root element of the document */ 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)) { parseDefaultElement(ele, delegate); //默认解析节点 } else { delegate.parseCustomElement(ele); //自定义解析 } } } } else { delegate.parseCustomElement(root); } }
持续点击进入默认解析：
private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) { if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) { // input解析 importBeanDefinitionResource(ele); } else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) { //别名解析 processAliasRegistration(ele); } else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) { //解析beans processBeanDefinition(ele, delegate); } else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) { // recurse doRegisterBeanDefinitions(ele); } }
持续查看解析bean：
processAliasRegistration(ele);
/** * Process the given bean element, parsing the bean definition * and registering it with the registry. */ protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) { BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele); if (bdHolder != null) { bdHolder = delegate.decorateBeanDefinitionIfRequired(ele, bdHolder); try { // Register the final decorated instance. BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry()); //可以持续点击查看这里 } catch (BeanDefinitionStoreException ex) { getReaderContext().error("Failed to register bean definition with name \'" + bdHolder.getBeanName() + "\'", ele, ex); } // Send registration event. getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder)); } }
可以持续点击查看这里
BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());
/** * Register the given bean definition with the given bean factory. * @param definitionHolder the bean definition including name and aliases * @param registry the bean factory to register with * @throws BeanDefinitionStoreException if registration failed */ public static void registerBeanDefinition( BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry) throws BeanDefinitionStoreException { // Register bean definition under primary name. String beanName = definitionHolder.getBeanName(); registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition()); //beanName beanId的名称 // Register aliases for bean name, if any. String[] aliases = definitionHolder.getAliases(); if (aliases != null) { for (String alias : aliases) { registry.registerAlias(beanName, alias); } } }
beanName beanId的名称 是通过
String beanName = definitionHolder.getBeanName();
获取的：点击查看 BeanDefinitionHolder bdHolder = delegate.parseBeanDefinitionElement(ele);
@Nullable public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, @Nullable BeanDefinition containingBean) { String id = ele.getAttribute(ID_ATTRIBUTE); //解析 id String nameAttr = ele.getAttribute(NAME_ATTRIBUTE); // 解析 name List<String> aliases = new ArrayList<>(); if (StringUtils.hasLength(nameAttr)) { String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS); aliases.addAll(Arrays.asList(nameArr)); } String beanName = id; //通过beanId 找 if (!StringUtils.hasText(beanName) && !aliases.isEmpty()) { beanName = aliases.remove(0); if (logger.isTraceEnabled()) { logger.trace("No XML \'id\' specified - using \'" + beanName + "\' as bean name and " + aliases + " as aliases"); } } if (containingBean == null) { checkNameUniqueness(beanName, aliases, ele); } AbstractBeanDefinition beanDefinition = parseBeanDefinitionElement(ele, beanName, containingBean); if (beanDefinition != null) { if (!StringUtils.hasText(beanName)) { try { if (containingBean != null) { beanName = BeanDefinitionReaderUtils.generateBeanName( beanDefinition, this.readerContext.getRegistry(), true); } else { beanName = this.readerContext.generateBeanName(beanDefinition); // Register an alias for the plain bean class name, if still possible, // if the generator returned the class name plus a suffix. // This is expected for Spring 1.2/2.0 backwards compatibility. String beanClassName = beanDefinition.getBeanClassName(); if (beanClassName != null && beanName.startsWith(beanClassName) && beanName.length() > beanClassName.length() && !this.readerContext.getRegistry().isBeanNameInUse(beanClassName)) { aliases.add(beanClassName); } } if (logger.isTraceEnabled()) { logger.trace("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); return new BeanDefinitionHolder(beanDefinition, beanName, aliasesArray); } return null; }
回退 查看注册的代码，持续点击进入：
BeanDefinitionReaderUtils.registerBeanDefinition(bdHolder, getReaderContext().getRegistry());
/** * Register the given bean definition with the given bean factory. * @param definitionHolder the bean definition including name and aliases * @param registry the bean factory to register with * @throws BeanDefinitionStoreException if registration failed */ public static void registerBeanDefinition( BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry) throws BeanDefinitionStoreException { // Register bean definition under primary name. String beanName = definitionHolder.getBeanName(); registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition()); //重点！！！ // Register aliases for bean name, if any. String[] aliases = definitionHolder.getAliases(); if (aliases != null) { for (String alias : aliases) { registry.registerAlias(beanName, alias); } } }
重点点击：
好几种注册方式：
选择一种：