码迷,mamicode.com
首页 > 移动开发 > 详细

ClassPathXmlApplicationContext 源代码阅读之我见

时间:2018-09-02 12:55:44      阅读:228      评论:0      收藏:0      [点我收藏+]

标签:ram   alter   转换   Opens   generator   element   抛出异常   ISE   catch   

由于本人的能力有限,只能说出自己的见解,如有错漏什么的,请大家批评指出。

由于代码封装太多,这里只列出了我认为的部分最重要的代码,一些简单的封装代码,不在下面列出。

由于代码太过于复杂,在本次博客中,只列出了关键的代码(包含代码在哪个类),具体的所有代码和细节,需要查看源码。
在源代码解读的时候,关键的方法代码,用红色字体,如:resolvePath(locations[i])。另外,所有具体的实现方法,都是以do开头的。
IOC容器生成,包括有定位、加载、注册三个步骤,下面介绍下xml配置方式的IOC容器的生成,通过注解方式生成的原理也是一样,不过要比这个简单些(不需要定位配置文件)。
ClassPathXmlApplicationContext:这是一个独立的xml的上下文bean,用于将普通的文件路劲加载解释、加载成为对应的bean,配置的路径方式可以是:/myfiles/context.xml 这种方式,也可以是:/myfiles/*-context 这种通配符的方式。

在ClassPathXmlApplicationContext中,有多个重载的构造方法,最重要的构造方法是:public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh, ApplicationContext parent)。具体代码如下:
/**
     * Create a new ClassPathXmlApplicationContext with the given parent,
     * loading the definitions from the given XML files.
     * @param configLocations array of resource locations
     * @param refresh whether to automatically refresh the context,
     * loading all bean definitions and creating all singletons.
     * Alternatively, call refresh manually after further configuring the context.
     * @param parent the parent context
     * @throws BeansException if context creation failed
     * @see #refresh()
     */
    //使用ApplicationContext容器创建一个ClassPathXmlApplicationContext容器,并从给定的xml文件中,加载定义的bean
    public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh, ApplicationContext parent)
            throws BeansException {

        super(parent);   //创建一个ApplicationContext 
        setConfigLocations(configLocations);   //为ApplicationContext 设置配置的位置(定位),如果没有设置,则使用默认的配置位置
        if (refresh) {
            refresh();   //刷新容器,这个方法很重要
        }
    }


下面介绍下setConfigLocations(configLocations),源代码如下:

/**
     * Set the config locations for this application context.
* 为application context设置(一个或多个)配置文件 * <p>If not set, the implementation may use a default as appropriate.
*/ public void setConfigLocations(String... locations) { if (locations != null) { Assert.noNullElements(locations, "Config locations must not be null"); this.configLocations = new String[locations.length]; for (int i = 0; i < locations.length; i++) { this.configLocations[i] = resolvePath(locations[i]).trim(); } } else { this.configLocations = null; } }
/**
     * Resolve the given path, replacing placeholders with corresponding
     * environment property values if necessary. Applied to config locations.
* 解析给定的路径,如果必要的话,用相应的环境属性值替换占位符来配置的位置,也就是${......} *
@param path the original file path * @return the resolved file path * @see org.springframework.core.env.Environment#resolveRequiredPlaceholders(String) */ protected String resolvePath(String path) { return getEnvironment().resolveRequiredPlaceholders(path); }
//实现方法在org\springframework\spring-core\4.3.13.RELEASE\spring-core-4.3.13.RELEASE-sources.jar!
//\org\springframework\core\env\AbstractPropertyResolver.java类中
@Override public String resolveRequiredPlaceholders(String text) throws IllegalArgumentException { if (this.strictHelper == null) { this.strictHelper = createPlaceholderHelper(false); } return doResolvePlaceholders(text, this.strictHelper); //真正的实现方法 }
/**
     * Replaces all placeholders of format {@code ${name}} with the value returned
     * from the supplied {@link PlaceholderResolver}.
* 替换所有的${name}的占位符 *
@param value the value containing the placeholders to be replaced * @param placeholderResolver the {@code PlaceholderResolver} to use for replacement * @return the supplied value with placeholders replaced inline */ public String replacePlaceholders(String value, PlaceholderResolver placeholderResolver) { Assert.notNull(value, "‘value‘ must not be null"); return parseStringValue(value, placeholderResolver, new HashSet<String>()); }
protected String parseStringValue(
            String value, PlaceholderResolver placeholderResolver, Set<String> visitedPlaceholders) {

        StringBuilder result = new StringBuilder(value);

        int startIndex = value.indexOf(this.placeholderPrefix);
        while (startIndex != -1) {
            int endIndex = findPlaceholderEndIndex(result, startIndex);
            if (endIndex != -1) {
                String placeholder = result.substring(startIndex + this.placeholderPrefix.length(), endIndex);
                String originalPlaceholder = placeholder;
                if (!visitedPlaceholders.add(originalPlaceholder)) {    //判断是否有闭环调用的占位符
                    throw new IllegalArgumentException(
                            "Circular placeholder reference ‘" + originalPlaceholder + "‘ in property definitions");
                }
                // Recursive invocation, parsing placeholders contained in the placeholder key.
          //递归调用,解析占位符键中包含的占位符。
placeholder = parseStringValue(placeholder, placeholderResolver, visitedPlaceholders); // Now obtain the value for the fully resolved key... --现在获得完全解析键的值 String propVal = placeholderResolver.resolvePlaceholder(placeholder); if (propVal == null && this.valueSeparator != null) { int separatorIndex = placeholder.indexOf(this.valueSeparator); if (separatorIndex != -1) { String actualPlaceholder = placeholder.substring(0, separatorIndex); String defaultValue = placeholder.substring(separatorIndex + this.valueSeparator.length()); propVal = placeholderResolver.resolvePlaceholder(actualPlaceholder); if (propVal == null) { propVal = defaultValue; } } } if (propVal != null) { // Recursive invocation, parsing placeholders contained in the // previously resolved placeholder value.
//递归调用,解析包含在先前解析的占位符值中的占位符
propVal = parseStringValue(propVal, placeholderResolver, visitedPlaceholders); result.replace(startIndex, endIndex + this.placeholderSuffix.length(), propVal); if (logger.isTraceEnabled()) { logger.trace("Resolved placeholder ‘" + placeholder + "‘"); } startIndex = result.indexOf(this.placeholderPrefix, startIndex + propVal.length()); } else if (this.ignoreUnresolvablePlaceholders) { // Proceed with unprocessed value. --处理未处理的占位符的值 startIndex = result.indexOf(this.placeholderPrefix, endIndex + this.placeholderSuffix.length()); } else { throw new IllegalArgumentException("Could not resolve placeholder ‘" + placeholder + "‘" + " in value \"" + value + "\""); } visitedPlaceholders.remove(originalPlaceholder); } else { startIndex = -1; } } return result.toString(); }

 跟踪查看,可以看到定位到的是这些形式的字符串:com.abc.model

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

继续跟进,查看 refresh() 方法,如下:

public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            // Prepare this context for refreshing.
            //刷新前准备工作
            prepareRefresh();

            // Tell the subclass to refresh the internal bean factory.
            //通知子类刷新内部bean工厂,这里是抽象工厂模式,就是返回一个factory---在这一步,做了加载的动作,并且也注册了bean定义(这个在代码里的确看到这个
//)
ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory(); // Prepare the bean factory for use in this context. //上下文使用bean工厂前准备工作,包括配置回调函数、不用注册的一些接口,默认的环境bean等一些标准的特性 prepareBeanFactory(beanFactory); try { // Allows post-processing of the bean factory in context subclasses. //允许子类中的bean工厂post操作,包括注册WebApplication特殊域如:request、response、sesseion、globalSession、application,还有注册环境bean,还有忽略一些接口 postProcessBeanFactory(beanFactory); // Invoke factory processors registered as beans in the context. //把工厂处理注册为上下文(context)中的bean,如果 invokeBeanFactoryPostProcessors(beanFactory); // Register bean processors that intercept bean creation. //注册用于拦截bean创建的bean处理器 registerBeanPostProcessors(beanFactory); // Initialize message source for this context. //初始化此上下文的消息源 initMessageSource(); // Initialize event multicaster for this context. //为上下文注册多(主机?转换)事件 initApplicationEventMulticaster(); // Initialize other special beans in specific context subclasses. onRefresh(); // Check for listener beans and register them. //初始化特定上下文子类中的其他特殊bean registerListeners(); // Instantiate all remaining (non-lazy-init) singletons. //实例化所有持有的(非延迟-init)单例 finishBeanFactoryInitialization(beanFactory); // Last step: publish corresponding event. //最后一步:发布相应的事件 finishRefresh(); } catch (BeansException ex) { if (logger.isWarnEnabled()) { logger.warn("Exception encountered during context initialization - " + "cancelling refresh attempt: " + ex); } // Destroy already created singletons to avoid dangling resources. //销毁已经创建的单例bean,以避免资源浪费 destroyBeans(); // Reset ‘active‘ flag. //重置存活标志 cancelRefresh(ex); // Propagate exception to caller. //抛出异常 throw ex; } finally { // Reset common introspection caches in Spring‘s core, since we // might not ever need metadata for singleton beans anymore... //重置spring 中的公共缓存,因为可能永远都不再需要这个bean resetCommonCaches(); } } }

 

下面查看 obtainFreshBeanFactory()方法

/**
     * Tell the subclass to refresh the internal bean factory.
* 告诉子类刷新内部bean工厂 *
@return the fresh BeanFactory instance * @see #refreshBeanFactory() * @see #getBeanFactory() */ protected ConfigurableListableBeanFactory obtainFreshBeanFactory() { refreshBeanFactory(); ConfigurableListableBeanFactory beanFactory = getBeanFactory(); if (logger.isDebugEnabled()) { logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory); } return beanFactory; }
//org\springframework\spring-context\4.3.13.RELEASE\spring-context-4.3.13.RELEASE-sources.jar!\org\springframework\context\support\AbstractRefreshableApplicationContext.java

/**
     * This implementation performs an actual refresh of this context‘s underlying
     * bean factory, shutting down the previous bean factory (if any) and
     * initializing a fresh bean factory for the next phase of the context‘s lifecycle.
*真正地实现对上下文的基础bean工厂执行实际的刷新,如果之前有了工厂,则关闭前一个bean工厂,并为上下文生命周期的下一阶段初始化一个新的bean工厂。
*/ @Override protected final void refreshBeanFactory() throws BeansException { if (hasBeanFactory()) { destroyBeans(); //销毁bean closeBeanFactory(); //关闭bean工厂 } try { DefaultListableBeanFactory beanFactory = createBeanFactory(); beanFactory.setSerializationId(getId());
//这里允许自定义bean工厂 customizeBeanFactory(beanFactory); loadBeanDefinitions(beanFactory);
synchronized (this.beanFactoryMonitor) { this.beanFactory = beanFactory; } } catch (IOException ex) { throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex); } }

 

//org\springframework\spring-context\4.3.13.RELEASE\spring-context-4.3.13.RELEASE-sources.jar!\org\springframework\context\support\AbstractXmlApplicationContext.java

/**
     * Loads the bean definitions via an XmlBeanDefinitionReader.
* 通过XmlBeanDefinitionReader装载bean定义 *
@see org.springframework.beans.factory.xml.XmlBeanDefinitionReader * @see #initBeanDefinitionReader * @see #loadBeanDefinitions */ @Override protected void loadBeanDefinitions(DefaultListableBeanFactory beanFactory) throws BeansException, IOException { // Create a new XmlBeanDefinitionReader for the given BeanFactory. XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory); // Configure the bean definition reader with this context‘s // resource loading environment. beanDefinitionReader.setEnvironment(this.getEnvironment()); beanDefinitionReader.setResourceLoader(this); 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); }
/**
     * Load the bean definitions with the given XmlBeanDefinitionReader.
* 使用给定的xmlBeanDefinitionReader加载Bean 定义 * <p>The lifecycle of the bean factory is handled by the {
@link #refreshBeanFactory} * method; hence this method is just supposed to load and/or register bean definitions. * @param reader the XmlBeanDefinitionReader to use * @throws BeansException in case of bean registration errors * @throws IOException if the required XML document isn‘t found * @see #refreshBeanFactory * @see #getConfigLocations * @see #getResources * @see #getResourcePatternResolver */ protected void loadBeanDefinitions(XmlBeanDefinitionReader reader) throws BeansException, IOException { Resource[] configResources = getConfigResources(); if (configResources != null) { reader.loadBeanDefinitions(configResources); } String[] configLocations = getConfigLocations(); if (configLocations != null) { reader.loadBeanDefinitions(configLocations); } }
// 这里使用循环,证明可以加载多个配置文件
@Override
public int loadBeanDefinitions(Resource... resources) throws BeanDefinitionStoreException { Assert.notNull(resources, "Resource array must not be null"); int counter = 0; for (Resource resource : resources) { counter += loadBeanDefinitions(resource); } return counter; }
//org\springframework\spring-beans\4.3.13.RELEASE\spring-beans-4.3.13.RELEASE-sources.jar!\org\springframework\beans\factory\groovy\GroovyBeanDefinitionReader.java
/**
* Load bean definitions from the specified Groovy script or XML file.
* 从指定的Groovy脚本或XML文件加载bean定义 * <p>Note that {
@code ".xml"} files will be parsed as XML content; all other kinds * of resources will be parsed as Groovy scripts. * @param resource the resource descriptor for the Groovy script or XML file * @return the number of bean definitions found * @throws BeanDefinitionStoreException in case of loading or parsing errors */ public int loadBeanDefinitions(Resource resource) throws BeanDefinitionStoreException { return loadBeanDefinitions(new EncodedResource(resource)); }
/**
     * Load bean definitions from the specified Groovy script or XML file.
* 从指定的Groovy脚本或XML文件加载bean定义 * <p>Note that {
@code ".xml"} files will be parsed as XML content; all other kinds * of resources will be parsed as Groovy scripts. * @param encodedResource the resource descriptor for the Groovy script or XML file, * allowing specification of 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 { // Check for XML files and redirect them to the "standard" XmlBeanDefinitionReader String filename = encodedResource.getResource().getFilename(); if (StringUtils.endsWithIgnoreCase(filename, ".xml")) { return this.standardXmlBeanDefinitionReader.loadBeanDefinitions(encodedResource); } Closure beans = new Closure(this) { public Object call(Object[] args) { invokeBeanDefiningClosure((Closure) args[0]); return null; } }; Binding binding = new Binding() { @Override public void setVariable(String name, Object value) { if (currentBeanDefinition != null) { applyPropertyToBeanDefinition(name, value); } else { super.setVariable(name, value); } } }; binding.setVariable("beans", beans); int countBefore = getRegistry().getBeanDefinitionCount(); try { GroovyShell shell = new GroovyShell(getResourceLoader().getClassLoader(), binding); shell.evaluate(encodedResource.getReader(), "beans"); } catch (Throwable ex) { throw new BeanDefinitionParsingException(new Problem("Error evaluating Groovy script: " + ex.getMessage(), new Location(encodedResource.getResource()), null, ex)); } return getRegistry().getBeanDefinitionCount() - countBefore; }
/**
     * 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.isInfoEnabled()) {
            logger.info("Loading XML bean definitions from " + encodedResource.getResource());
        }

        Set<EncodedResource> currentResources = this.resourcesCurrentlyBeingLoaded.get();
        if (currentResources == null) {
            currentResources = new HashSet<EncodedResource>(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();
            try {
                InputSource inputSource = new InputSource(inputStream);
                if (encodedResource.getEncoding() != null) {
                    inputSource.setEncoding(encodedResource.getEncoding());
                }
                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();
            }
        }
    }
/**
     * Actually load bean definitions from the specified XML file.
* 从指定的xml文件中,实际执行加载bean定义的方法 *
@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); return registerBeanDefinitions(doc, resource); } 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); } }
/**
     * Register the bean definitions contained in the given DOM document.    --注册包含在给定的dom中的bean定义
     * Called by {@code loadBeanDefinitions}.
     * <p>Creates a new instance of the parser class and invokes
     * {@code registerBeanDefinitions} on it.
     * @param doc the DOM document
     * @param resource the resource descriptor (for context information)
     * @return the number of bean definitions found
     * @throws BeanDefinitionStoreException in case of parsing errors
     * @see #loadBeanDefinitions
     * @see #setDocumentReaderClass
     * @see BeanDefinitionDocumentReader#registerBeanDefinitions
     */
    public int registerBeanDefinitions(Document doc, Resource resource) throws BeanDefinitionStoreException {
        BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
        int countBefore = getRegistry().getBeanDefinitionCount();
        documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
        return getRegistry().getBeanDefinitionCount() - countBefore;
    }
//org\springframework\spring-beans\4.3.13.RELEASE\spring-beans-4.3.13.RELEASE-sources.jar!\org\springframework\beans\factory\xml\DefaultBeanDefinitionDocumentReader.java

/**
     * This implementation parses bean definitions according to the "spring-beans" XSD
* 根据“spring-beans”XSD解析bean定义 * (or DTD, historically). * <p>Opens a DOM Document; then initializes the default settings * specified at the {
@code <beans/>} level; then parses the contained bean definitions. */ @Override public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) { this.readerContext = readerContext; logger.debug("Loading bean definitions"); Element root = doc.getDocumentElement(); doRegisterBeanDefinitions(root); }
/**
     * Register each bean definition within the given root {@code <beans/>} element.
* 注册根节点内的每一个bean定义
*/ 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); 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; } } } preProcessXml(root); parseBeanDefinitions(root, this.delegate); postProcessXml(root); this.delegate = parent; }
/**
     * Parse the elements at the root level in the document:   -转换根节点
     * "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;
//判断是否是默认的命名空间:http://www.springframework.org/schema/beans,一般情况下我们都是放在这个命名空间下
if (delegate.isDefaultNamespace(ele)) { parseDefaultElement(ele, delegate); } else { delegate.parseCustomElement(ele); } } } } else { delegate.parseCustomElement(root); } }
private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {
        if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) {   //import 标签
            importBeanDefinitionResource(ele);
        }
        else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) {   //alias标签
            processAliasRegistration(ele);
        }
        else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) {    //bean 标签
            processBeanDefinition(ele, delegate);
        }
        else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {    //beans标签。注意,这里有递归调用。这里实际上也调用了上面的processBeanDefinition方法
            // recurse
            doRegisterBeanDefinitions(ele);
        }
    }
/**
     * Process the given bean element, parsing the bean definition   --转换成bean定义
     * 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());
            }
            catch (BeanDefinitionStoreException ex) {
                getReaderContext().error("Failed to register bean definition with name ‘" +
                        bdHolder.getBeanName() + "‘", ele, ex);
            }
            // Send registration event.
            getReaderContext().fireComponentRegistered(new BeanComponentDefinition(bdHolder));
        }
    }
/**
     * Parses the supplied {@code <bean>} element. May return {@code null}
     * if there were errors during parse. Errors are reported to the
     * {@link org.springframework.beans.factory.parsing.ProblemReporter}.
     */
    public BeanDefinitionHolder parseBeanDefinitionElement(Element ele) {
        return parseBeanDefinitionElement(ele, null);
    }

    /**
     * Parses the supplied {@code <bean>} element. May return {@code null}
     * if there were errors during parse. Errors are reported to the
     * {@link org.springframework.beans.factory.parsing.ProblemReporter}.
     */
    public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, BeanDefinition containingBean) {
        String id = ele.getAttribute(ID_ATTRIBUTE);
        String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);

        List<String> aliases = new ArrayList<String>();
        if (StringUtils.hasLength(nameAttr)) {
            String[] nameArr = StringUtils.tokenizeToStringArray(nameAttr, MULTI_VALUE_ATTRIBUTE_DELIMITERS);
            aliases.addAll(Arrays.asList(nameArr));
        }

        String beanName = id;
        if (!StringUtils.hasText(beanName) && !aliases.isEmpty()) {
            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) {
            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.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);
            return new BeanDefinitionHolder(beanDefinition, beanName, aliasesArray);
        }

        return null;
    }
/**
     * Parse the bean definition itself, without regard to name or aliases. May return 
* 解析bean定义本身,而不考虑名称或别名 * {
@code null} if problems occurred during the parsing of the bean definition. */ public AbstractBeanDefinition parseBeanDefinitionElement( Element ele, String beanName, BeanDefinition containingBean) { this.parseState.push(new BeanEntry(beanName)); String className = null; if (ele.hasAttribute(CLASS_ATTRIBUTE)) { className = ele.getAttribute(CLASS_ATTRIBUTE).trim(); } try { String parent = null; if (ele.hasAttribute(PARENT_ATTRIBUTE)) { parent = ele.getAttribute(PARENT_ATTRIBUTE); } AbstractBeanDefinition bd = createBeanDefinition(className, parent);
//将给定bean元素的属性应用于给定bean *定义,如:singleton、scope、abstract、lazy-init 等属性 parseBeanDefinitionAttributes(ele, beanName, containingBean, bd);
//设置描述为可阅读 bd.setDescription(DomUtils.getChildElementValueByTagName(ele, DESCRIPTION_ELEMENT));
//设置元数据属性 parseMetaElements(ele, bd);
//解析查找覆盖给定bean元素的子元素 parseLookupOverrideSubElements(ele, bd.getMethodOverrides());
//解释给定的bean的子元素的替换方法 parseReplacedMethodSubElements(ele, bd.getMethodOverrides());
//解释给定bean元素的构造函数的子元素 parseConstructorArgElements(ele, bd);
//解释给定的bean元素的子元素的属性 parsePropertyElements(ele, bd);
//解释给定的bean元素的子元素的限定符 parseQualifierElements(ele, bd);
//设置bean定义的来源 bd.setResource(this.readerContext.getResource()); 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 { this.parseState.pop(); } return null; }

 下面贴出加载xml文件中的属性配置的源代码

/**
     * Parse property sub-elements of the given bean element.
     */
    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)) {
                parsePropertyElement((Element) node, bd);
            }
        }
    }
/**
     * Parse a property element.
     */
    public void parsePropertyElement(Element ele, BeanDefinition bd) {
        String propertyName = ele.getAttribute(NAME_ATTRIBUTE);
        if (!StringUtils.hasLength(propertyName)) {
            error("Tag ‘property‘ must have a ‘name‘ attribute", ele);
            return;
        }
        this.parseState.push(new PropertyEntry(propertyName));
        try {
            if (bd.getPropertyValues().contains(propertyName)) {
                error("Multiple ‘property‘ definitions for property ‘" + propertyName + "‘", ele);
                return;
            }
            Object val = parsePropertyValue(ele, bd, propertyName);
            PropertyValue pv = new PropertyValue(propertyName, val);
            parseMetaElements(ele, pv);
            pv.setSource(extractSource(ele));
            bd.getPropertyValues().addPropertyValue(pv);
        }
        finally {
            this.parseState.pop();
        }
    }
/**
     * Get the value of a property element. May be a list etc.
     * Also used for constructor arguments, "propertyName" being null in this case.
     */
    public Object parsePropertyValue(Element ele, BeanDefinition bd, String propertyName) {
        String elementName = (propertyName != null) ?
                        "<property> element for property ‘" + propertyName + "‘" :
                        "<constructor-arg> element";

        // Should only have one child element: ref, value, list, etc.
        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)) {
                // Child element is what we‘re looking for.
                if (subElement != null) {
                    error(elementName + " must not contain more than one sub-element", ele);
                }
                else {
                    subElement = (Element) node;
                }
            }
        }

        boolean hasRefAttribute = ele.hasAttribute(REF_ATTRIBUTE);
        boolean hasValueAttribute = ele.hasAttribute(VALUE_ATTRIBUTE);
        if ((hasRefAttribute && hasValueAttribute) ||
                ((hasRefAttribute || hasValueAttribute) && subElement != null)) {
            error(elementName +
                    " is only allowed to contain either ‘ref‘ attribute OR ‘value‘ attribute OR sub-element", ele);
        }

        if (hasRefAttribute) {
            String refName = ele.getAttribute(REF_ATTRIBUTE);
            if (!StringUtils.hasText(refName)) {
                error(elementName + " contains empty ‘ref‘ attribute", ele);
            }
            RuntimeBeanReference ref = new RuntimeBeanReference(refName);
            ref.setSource(extractSource(ele));
            return ref;
        }
        else if (hasValueAttribute) {
            TypedStringValue valueHolder = new TypedStringValue(ele.getAttribute(VALUE_ATTRIBUTE));
            valueHolder.setSource(extractSource(ele));
            return valueHolder;
        }
        else if (subElement != null) {
            return parsePropertySubElement(subElement, bd);
        }
        else {
            // Neither child element nor "ref" or "value" attribute found.
            error(elementName + " must specify a ref or value", ele);
            return null;
        }
    }
public Object parsePropertySubElement(Element ele, BeanDefinition bd) {
        return parsePropertySubElement(ele, bd, null);
    }

    /**
     * Parse a value, ref or collection sub-element of a property or
     * constructor-arg element.
     * @param ele subelement of property element; we don‘t know which yet
     * @param defaultValueType the default type (class name) for any
     * {@code <value>} tag that might be created
     */
    public Object parsePropertySubElement(Element ele, BeanDefinition bd, String defaultValueType) {
        if (!isDefaultNamespace(ele)) {
            return parseNestedCustomElement(ele, bd);
        }
        else if (nodeNameEquals(ele, BEAN_ELEMENT)) {
            BeanDefinitionHolder nestedBd = parseBeanDefinitionElement(ele, bd);
            if (nestedBd != null) {
                nestedBd = decorateBeanDefinitionIfRequired(ele, nestedBd, bd);
            }
            return nestedBd;
        }
        else if (nodeNameEquals(ele, REF_ELEMENT)) {
            // A generic reference to any name of any bean.
            String refName = ele.getAttribute(BEAN_REF_ATTRIBUTE);
            boolean toParent = false;
            if (!StringUtils.hasLength(refName)) {
                // A reference to the id of another bean in the same XML file.
                refName = ele.getAttribute(LOCAL_REF_ATTRIBUTE);
                if (!StringUtils.hasLength(refName)) {
                    // A reference to the id of another bean in a parent context.
                    refName = ele.getAttribute(PARENT_REF_ATTRIBUTE);
                    toParent = true;
                    if (!StringUtils.hasLength(refName)) {
                        error("‘bean‘, ‘local‘ or ‘parent‘ is required for <ref> element", ele);
                        return null;
                    }
                }
            }
            if (!StringUtils.hasText(refName)) {
                error("<ref> element contains empty target attribute", ele);
                return null;
            }
            RuntimeBeanReference ref = new RuntimeBeanReference(refName, toParent);
            ref.setSource(extractSource(ele));
            return ref;
        }
        else if (nodeNameEquals(ele, IDREF_ELEMENT)) {
            return parseIdRefElement(ele);
        }
        else if (nodeNameEquals(ele, VALUE_ELEMENT)) {
            return parseValueElement(ele, defaultValueType);
        }
        else if (nodeNameEquals(ele, NULL_ELEMENT)) {
            // It‘s a distinguished null value. Let‘s wrap it in a TypedStringValue
            // object in order to preserve the source location.
            TypedStringValue nullHolder = new TypedStringValue(null);
            nullHolder.setSource(extractSource(ele));
            return nullHolder;
        }
        else if (nodeNameEquals(ele, ARRAY_ELEMENT)) {
            return parseArrayElement(ele, bd);
        }
        else if (nodeNameEquals(ele, LIST_ELEMENT)) {
            return parseListElement(ele, bd);
        }
        else if (nodeNameEquals(ele, SET_ELEMENT)) {
            return parseSetElement(ele, bd);
        }
        else if (nodeNameEquals(ele, MAP_ELEMENT)) {
            return parseMapElement(ele, bd);
        }
        else if (nodeNameEquals(ele, PROPS_ELEMENT)) {
            return parsePropsElement(ele);
        }
        else {
            error("Unknown property sub-element: [" + ele.getNodeName() + "]", ele);
            return null;
        }
    }

从上面可以看到,xml中支持的map、list、set、props、array这些属性,都是在这里方法中进行最终的处理。以上的代码,是比较关键的加载bean的代码

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

下面阅读 invokeBeanFactoryPostProcessors(beanFactory)

/**
     * Instantiate and invoke all registered BeanFactoryPostProcessor beans,
     * respecting explicit order if given.
     * <p>Must be called before singleton instantiation.
     */

//初始化bean并执行所有已经注册bean工厂后置处理器,如果有排序,则按照排序进行处理华
//这里要注意的:必须在单例bean的实例化之前执行这个bean工厂的初始化,因为单例模式是程序运行的时候就已经创建,而普通bean则是在调用时候,才会初始化 protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) { PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors()); // Detect a LoadTimeWeaver and prepare for weaving, if found in the meantime // (e.g. through an @Bean method registered by ConfigurationClassPostProcessor) if (beanFactory.getTempClassLoader() == null && beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) { beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory)); beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader())); } }
public static void invokeBeanFactoryPostProcessors(
            ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {

        // Invoke BeanDefinitionRegistryPostProcessors first, if any.
        Set<String> processedBeans = new HashSet<String>();

//如果是注册的工厂bean,则先于普通的bean先初始化
if (beanFactory instanceof BeanDefinitionRegistry) { BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory; List<BeanFactoryPostProcessor> regularPostProcessors = new LinkedList<BeanFactoryPostProcessor>(); List<BeanDefinitionRegistryPostProcessor> registryProcessors = new LinkedList<BeanDefinitionRegistryPostProcessor>(); for (BeanFactoryPostProcessor postProcessor : beanFactoryPostProcessors) { if (postProcessor instanceof BeanDefinitionRegistryPostProcessor) { BeanDefinitionRegistryPostProcessor registryProcessor = (BeanDefinitionRegistryPostProcessor) postProcessor; registryProcessor.postProcessBeanDefinitionRegistry(registry); registryProcessors.add(registryProcessor); } else { regularPostProcessors.add(postProcessor); } } // Do not initialize FactoryBeans here: We need to leave all regular beans // uninitialized to let the bean factory post-processors apply to them! // Separate between BeanDefinitionRegistryPostProcessors that implement // PriorityOrdered, Ordered, and the rest.

//
不要在这里初始化factorybean:因为需要保证所有的普通的bean在后置处理器中使用到(我想应该是调用的时候会用到吧,这个不确定)

List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<BeanDefinitionRegistryPostProcessor>();
            // First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
// 首先,先初始化实现(使用)
PriorityOrdered接口的bean
            String[] postProcessorNames =
                    beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
            for (String ppName : postProcessorNames) {
                if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
                    currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
                    processedBeans.add(ppName);
                }
            }
            sortPostProcessors(currentRegistryProcessors, beanFactory);
            registryProcessors.addAll(currentRegistryProcessors);
            invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
            currentRegistryProcessors.clear();  //这里有清理动作,也就是设置为null

            // Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
// 接下来,执行实现了Ordered接口的注册(性质)的后置工厂处理器
postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { if (!processedBeans.contains(ppName) && beanFactory.isTypeMatch(ppName, Ordered.class)) { currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); } } sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); // Finally, invoke all other BeanDefinitionRegistryPostProcessors until no further ones appear.
//最后,执行所有其他的注册(性质的)bean工厂后置处理器
boolean reiterate = true; while (reiterate) { reiterate = false; postProcessorNames = beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false); for (String ppName : postProcessorNames) { if (!processedBeans.contains(ppName)) { currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class)); processedBeans.add(ppName); reiterate = true; } } sortPostProcessors(currentRegistryProcessors, beanFactory); registryProcessors.addAll(currentRegistryProcessors); invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry); currentRegistryProcessors.clear(); } // Now, invoke the postProcessBeanFactory callback of all processors handled so far. invokeBeanFactoryPostProcessors(registryProcessors, beanFactory); invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory); } else { // Invoke factory processors registered with the context instance.
// 执行上下文注册的工厂后置处理器,我们自定义的bean就是在这一步执行
invokeBeanFactoryPostProcessors(beanFactoryPostProcessors, beanFactory); } // Do not initialize FactoryBeans here: We need to leave all regular beans // uninitialized to let the bean factory post-processors apply to them! String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanFactoryPostProcessor.class, true, false); // Separate between BeanFactoryPostProcessors that implement PriorityOrdered, // Ordered, and the rest. List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); List<String> orderedPostProcessorNames = new ArrayList<String>(); List<String> nonOrderedPostProcessorNames = new ArrayList<String>(); for (String ppName : postProcessorNames) { if (processedBeans.contains(ppName)) { // skip - already processed in first phase above } else if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) { priorityOrderedPostProcessors.add(beanFactory.getBean(ppName, BeanFactoryPostProcessor.class)); } else if (beanFactory.isTypeMatch(ppName, Ordered.class)) { orderedPostProcessorNames.add(ppName); } else { nonOrderedPostProcessorNames.add(ppName); } } // First, invoke the BeanFactoryPostProcessors that implement PriorityOrdered. sortPostProcessors(priorityOrderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(priorityOrderedPostProcessors, beanFactory); // Next, invoke the BeanFactoryPostProcessors that implement Ordered. List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); for (String postProcessorName : orderedPostProcessorNames) { orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } sortPostProcessors(orderedPostProcessors, beanFactory); invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory); // Finally, invoke all other BeanFactoryPostProcessors. List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanFactoryPostProcessor>(); for (String postProcessorName : nonOrderedPostProcessorNames) { nonOrderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class)); } invokeBeanFactoryPostProcessors(nonOrderedPostProcessors, beanFactory); // Clear cached merged bean definitions since the post-processors might have // modified the original metadata, e.g. replacing placeholders in values... beanFactory.clearMetadataCache(); }

上面要注意几点:1、执行初始化工厂后置处理器,不会实例化已加载定义的bean  2、初始化工厂后置处理器,必须在单例bean的实例化之前,因为单例bean是运行时候就已经实例化  3、初始化的执行,是有顺序的

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

下面阅读 registerBeanPostProcessors(beanFactory)

/**
     * Instantiate and invoke all registered BeanPostProcessor beans,
     * respecting explicit order if given.
     * <p>Must be called before any instantiation of application beans.
     */
//初始化并执行所有已注册的bean后置处理器bean,如果有排序,则按照排序进行初始化和执行。
//必须在任何上下文bean实例化之前调用,(不确定)是因为上下文的bean是在运行时候就已经实例化
protected void registerBeanPostProcessors(ConfigurableListableBeanFactory beanFactory) { PostProcessorRegistrationDelegate.registerBeanPostProcessors(beanFactory, this); //这里是个委托模式 }
public static void registerBeanPostProcessors(
            ConfigurableListableBeanFactory beanFactory, AbstractApplicationContext applicationContext) {

        String[] postProcessorNames = beanFactory.getBeanNamesForType(BeanPostProcessor.class, true, false);

        // Register BeanPostProcessorChecker that logs an info message when
        // a bean is created during BeanPostProcessor instantiation, i.e. when
        // a bean is not eligible for getting processed by all BeanPostProcessors.
//
注册BeanPostProcessorChecker,它记录信息消息bean是在BeanPostProcessor实例化期间创建的,
//也就是说,当bean不适合由所有BeanPostProcessor进行处理时。-----
        int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
        beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

        // Separate between BeanPostProcessors that implement PriorityOrdered,
        // Ordered, and the rest.
        List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
        List<BeanPostProcessor> internalPostProcessors = new ArrayList<BeanPostProcessor>();
        List<String> orderedPostProcessorNames = new ArrayList<String>();
        List<String> nonOrderedPostProcessorNames = new ArrayList<String>();
        for (String ppName : postProcessorNames) {
            if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {
                BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
                priorityOrderedPostProcessors.add(pp);
                if (pp instanceof MergedBeanDefinitionPostProcessor) {
                    internalPostProcessors.add(pp);
                }
            }
            else if (beanFactory.isTypeMatch(ppName, Ordered.class)) {
                orderedPostProcessorNames.add(ppName);
            }
            else {
                nonOrderedPostProcessorNames.add(ppName);
            }
        }

        // First, register the BeanPostProcessors that implement PriorityOrdered.
        sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
        registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

        // Next, register the BeanPostProcessors that implement Ordered.
        List<BeanPostProcessor> orderedPostProcessors = new ArrayList<BeanPostProcessor>();
        for (String ppName : orderedPostProcessorNames) {
            BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
            orderedPostProcessors.add(pp);
            if (pp instanceof MergedBeanDefinitionPostProcessor) {
                internalPostProcessors.add(pp);
            }
        }
        sortPostProcessors(orderedPostProcessors, beanFactory);
        registerBeanPostProcessors(beanFactory, orderedPostProcessors);

        // Now, register all regular BeanPostProcessors.
        List<BeanPostProcessor> nonOrderedPostProcessors = new ArrayList<BeanPostProcessor>();
        for (String ppName : nonOrderedPostProcessorNames) {
            BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
            nonOrderedPostProcessors.add(pp);
            if (pp instanceof MergedBeanDefinitionPostProcessor) {
                internalPostProcessors.add(pp);
            }
        }
        registerBeanPostProcessors(beanFactory, nonOrderedPostProcessors);

        // Finally, re-register all internal BeanPostProcessors.
// 重注册所有的内部bean后置处理器(为什么呢?)
sortPostProcessors(internalPostProcessors, beanFactory); registerBeanPostProcessors(beanFactory, internalPostProcessors); // Re-register post-processor for detecting inner beans as ApplicationListeners, // moving it to the end of the processor chain (for picking up proxies etc).
//重新注册后处理器以检测内部bean作为applicationlistener,将其移动到处理器链的末尾(用于获取代理等)
beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext)); }

上面这段代码,跟invokeBeanFactoryPostProcessors(beanFactory) 很像是吧。惊不惊喜,意不意外!

Override
    public void addBeanPostProcessor(BeanPostProcessor beanPostProcessor) {
        Assert.notNull(beanPostProcessor, "BeanPostProcessor must not be null");
        this.beanPostProcessors.remove(beanPostProcessor);
        this.beanPostProcessors.add(beanPostProcessor);
        if (beanPostProcessor instanceof InstantiationAwareBeanPostProcessor) {
            this.hasInstantiationAwareBeanPostProcessors = true;
        }
        if (beanPostProcessor instanceof DestructionAwareBeanPostProcessor) {
            this.hasDestructionAwareBeanPostProcessors = true;
        }
    }
/** BeanPostProcessors to apply in createBean */
    private final List<BeanPostProcessor> beanPostProcessors = new ArrayList<BeanPostProcessor>();

查看这个addProcessor,其实就是在一个list里面先remove,然后add

 

 

-----------------------------------------------------------------------------------------------------------------------------------------------------------------

到目前为止,已经阅读完所有的关键代码。当然了,由于本人水平有限,也是第一次阅读这个代码,中间肯定有很多理解不到位,甚至错误的地方,请各位大神批评指正。欢迎留言交流。

 

ClassPathXmlApplicationContext 源代码阅读之我见

标签:ram   alter   转换   Opens   generator   element   抛出异常   ISE   catch   

原文地址:https://www.cnblogs.com/drafire/p/9564772.html

(0)
(0)
   
举报
评论 一句话评论(0
登录后才能评论!
© 2014 mamicode.com 版权所有  联系我们:gaon5@hotmail.com
迷上了代码!