spring源码学习

spring架构

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按照图中的流程,一定要自己使用idea工具配合着debug,慢慢去看里面源码,除了花费一点时间,不会很难,绝对可以理解的
spring测试用例:
maven依赖:

	<dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.2.12.RELEASE</version>
        </dependency>
    </dependencies>

测试类:

import lombok.Data;

@Data
public class Person {
    private int id;
    private String name;
    private int age;
    private String gender;

}

application.xml配置文件:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!--注册一个对象,spring回自动创建这个对象-->
    <!--
    一个bean标签就表示一个对象
    id:这个对象的唯一标识
    class:注册对象的完全限定名
    -->
    <bean id="person" class="com.biao.java8.spring.Person">
        <!--使用property标签给对象的属性赋值
        name:表示属性的名称
        value:表示属性的值
        -->
        <property name="id" value="1"></property>
        <property name="name" value="zhangsan"></property>
        <property name="age" value="18"></property>
        <property name="gender" value="男"></property>
    </bean>
</beans>

启动类:

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringDemoTest {
    public static void main(String[] args) {
        //ApplicationContext:表示spring容器
        //ClassPathXmlApplicationContext:表示从当前classpath路径中获取xml文件的配置
        //根据spring的配置文件来获取ioc容器对象
        ApplicationContext context = new ClassPathXmlApplicationContext("application.xml");
        Person person = context.getBean("person", Person.class);
        System.out.println(person);
    }
}

先允许确保正常打印person对象无误,打上断点,进行调式,deg代码
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使用F7进入代码内部,这里处理了一个WebLogic 8.1应用关闭的bug,在AbstractApplicationContext类中
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继续F7往下走,又回来了
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继续F7进去往下走,调用了ClassPathXmlApplicationContext的构造方法
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继续F7进去往下走,在构造方法中做了一些事情
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这里调用了父类的构造方法,获取到了资源处理器
获取到了配置文件application.xml,使用setConfigLocations()放到了ConfigLocations,所以后面肯定会用到
然后调用了refresh();方法,

F7进入查看这个方法,里面一共调用了13个方法

	@Override
	public void refresh() throws BeansException, IllegalStateException {
		synchronized (this.startupShutdownMonitor) {
			// Prepare this context for refreshing.
			prepareRefresh();

			// Tell the subclass to refresh the internal bean factory.
			ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

			// Prepare the bean factory for use in this context.
			prepareBeanFactory(beanFactory);

			try {
				// Allows post-processing of the bean factory in context subclasses.
				postProcessBeanFactory(beanFactory);

				// Invoke factory processors registered as beans in the context.
				invokeBeanFactoryPostProcessors(beanFactory);

				// Register bean processors that intercept bean creation.
				registerBeanPostProcessors(beanFactory);

				// Initialize message source for this context.
				initMessageSource();

				// Initialize event multicaster for this context.
				initApplicationEventMulticaster();

				// Initialize other special beans in specific context subclasses.
				onRefresh();

				// Check for listener beans and register them.
				registerListeners();

				// Instantiate all remaining (non-lazy-init) singletons.
				finishBeanFactoryInitialization(beanFactory);

				// Last step: publish corresponding event.
				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.
				destroyBeans();

				// Reset 'active' flag.
				cancelRefresh(ex);

				// Propagate exception to caller.
				throw ex;
			}

			finally {
				// Reset common introspection caches in Spring's core, since we
				// might not ever need metadata for singleton beans anymore...
				resetCommonCaches();
			}
		}
	}

1、prepareRefresh();

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refresh()方法刚进来时候,首先有个同步操作,开启和关闭不能同事进行,然后调用了prepareRefresh();方法
使用F7进去查看prepareRefresh()方法,有些有些注释是我手动加的说明

	protected void prepareRefresh() {
		// Switch to active.
		this.startupDate = System.currentTimeMillis();		// 设置开始时间
		this.closed.set(false);		// 设置ioc容器的状态,closed是关闭的
		this.active.set(true);		// active 是true的

		if (logger.isDebugEnabled()) {
			if (logger.isTraceEnabled()) {
				logger.trace("Refreshing " + this);
			}
			else {
				logger.debug("Refreshing " + getDisplayName());
			}
		}

		// Initialize any placeholder property sources in the context environment.
		initPropertySources();		// 初始化子类扩展的一些东西

		// Validate that all properties marked as required are resolvable:
		// see ConfigurablePropertyResolver#setRequiredProperties
		getEnvironment().validateRequiredProperties();

		// Store pre-refresh ApplicationListeners...
		if (this.earlyApplicationListeners == null) {
		// 创建空的集合存放监听事件
			this.earlyApplicationListeners = new LinkedHashSet<>(this.applicationListeners);
		}
		else {
			// Reset local application listeners to pre-refresh state.
			this.applicationListeners.clear();
			this.applicationListeners.addAll(this.earlyApplicationListeners);
		}

		// Allow for the collection of early ApplicationEvents,
		// to be published once the multicaster is available...
		this.earlyApplicationEvents = new LinkedHashSet<>();
	}

2、obtainFreshBeanFactory(); 重点

obtainFreshBeanFactory();方法上面的注释说了,告诉子类刷新内部bean工厂
F7进入方法看到里面调用了2个方法,一个是刷新bean工厂,一个是获取bean工厂,主要是看refreshBeanFactory(), getBeanFactory()方法基本没做什么事
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进入到refreshBeanFactory()方法里面,查看这个刷新BeanFactory的方法

	/**
	 * 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.
	 */
	@Override
	protected final void refreshBeanFactory() throws BeansException {
		if (hasBeanFactory()) {		// 这里很明显是判断有没有BeanFactory
			// 如果已经有BeanFactory,就给销毁掉
			destroyBeans();
			closeBeanFactory();
		}
		try {
			DefaultListableBeanFactory beanFactory = createBeanFactory();	// 准备创建BeanFactory,方法在下面看
			beanFactory.setSerializationId(getId());	// 这个时候,上面一行代码已经创建好BeanFactory了,给BeanFactory存放序列化id
			customizeBeanFactory(beanFactory);	// 给BeanFactory设置自定义的功能,这个时候BeanFactory是空的,所以啥也没做
			loadBeanDefinitions(beanFactory); // 合理非常重要,把bean的值放进BeanFactory进行加载过程,看下面的loadBeanDefinitions()方法介绍
			this.beanFactory = beanFactory;
		}
		catch (IOException ex) {
			throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
		}
	}

createBeanFactory()

createBeanFactory()方法,返回的是一个DefaultListableBeanFactory,这里最后返回的就是一个空对象,自己可以debug时候点进去看看

	protected DefaultListableBeanFactory createBeanFactory() {
		// getInternalParentBeanFactory() 返回的是个空的,所以直接看DefaultListableBeanFactory的构造方法,调用了supper()方法,里面调用到AbstractAutowireCapableBeanFactory()方法
		return new DefaultListableBeanFactory(getInternalParentBeanFactory());
	}

DefaultListableBeanFactory构造方法调用supper,里面调用了下面代码AbstractAutowireCapableBeanFactory()方法

	public AbstractAutowireCapableBeanFactory() {
		super();	// 调用父类创建抽象工厂,中间会把所有属性的值进行填充,可以自己在这里去具体细看
		// 给ignoreDependencyInterface这个集合存放下面的3个Aware
		ignoreDependencyInterface(BeanNameAware.class);
		ignoreDependencyInterface(BeanFactoryAware.class);
		ignoreDependencyInterface(BeanClassLoaderAware.class);
	}
	
	/**
	 * Create a new AbstractAutowireCapableBeanFactory with the given parent.
	 * @param parentBeanFactory parent bean factory, or {@code null} if none
	 */
	public AbstractAutowireCapableBeanFactory(@Nullable BeanFactory parentBeanFactory) {
		this();		// 这个this()调用的是上面的AbstractAutowireCapableBeanFactory方法
		setParentBeanFactory(parentBeanFactory);	// 这个parentBeanFactory是空的
	}

loadBeanDefinitions()

	/**
	 * Loads the bean definitions via an XmlBeanDefinitionReader.
	 * @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.创建XmlBeanDefinitionReader,可以自己调试进入查看做了什么
		XmlBeanDefinitionReader beanDefinitionReader = new XmlBeanDefinitionReader(beanFactory);

		// Configure the bean definition reader with this context's
		// resource loading environment.
		beanDefinitionReader.setEnvironment(this.getEnvironment());		给BeanDefinitionReader存放当前环境的对象
		beanDefinitionReader.setResourceLoader(this);	// 设置资源加载器,存放的是当前类的本身,是ClassPathXmlApplicationContext
		beanDefinitionReader.setEntityResolver(new ResourceEntityResolver(this));	// 这个是为了处理xml文件,可以点进去看一下,主要是获取类加载器,把资源值加载进去,然后设置到EntityResolver里面

		// Allow a subclass to provide custom initialization of the reader,
		// then proceed with actually loading the bean definitions.
		initBeanDefinitionReader(beanDefinitionReader);		// 给beanDefinitionReader进行初始化工作,主要是进行最基本的一个验证xml,这里不是太难,可以自己点进去看看
		loadBeanDefinitions(beanDefinitionReader);		// 开始真正的加载过程,这里非常重要
	}

loadBeanDefinitions()

	/**
	 * Load the bean definitions with the given XmlBeanDefinitionReader.
	 * <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();		// 获取资源,这里是没有的,所以为空
		if (configResources != null) {
			reader.loadBeanDefinitions(configResources);
		}
		String[] configLocations = getConfigLocations();		// 这里是获取资源路径,就是获取到application.xml文件,想不起来的话看下面这个图,这时候肯定有值,所以进入下面判断里
		if (configLocations != null) {
			reader.loadBeanDefinitions(configLocations);	// 开始进行整体的一个加载过程,看下面的具体代码
		}
	}

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loadBeanDefinitions
	@Override
	public int loadBeanDefinitions(String... locations) throws BeanDefinitionStoreException {
		Assert.notNull(locations, "Location array must not be null");
		int count = 0;
		for (String location : locations) {
			count += loadBeanDefinitions(location);		// 因为传的参数是数组,所以要遍历,看下面的loadBeanDefinitions具体实现代码,是又一个loadBeanDefinitions的重载方法代码
		}
		return count;
	}
loadBeanDefinitions
public int loadBeanDefinitions(String location, @Nullable Set<Resource> actualResources) throws BeanDefinitionStoreException {
		ResourceLoader resourceLoader = getResourceLoader();	// 前面已经知道了资源路径,所以在这里进行加载过来
		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 {
				// 这一行代码做了处理,把location加进去,然后获取Resources资源,自己点进去看看,调用的getResources方法在下面查看代码
				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 {
			// Can only load single resources by absolute URL.
			Resource resource = resourceLoader.getResource(location);
			int count = loadBeanDefinitions(resource);
			if (actualResources != null) {
				actualResources.add(resource);
			}
			if (logger.isTraceEnabled()) {
				logger.trace("Loaded " + count + " bean definitions from location [" + location + "]");
			}
			return count;
		}
	}
getResources()
	public Resource[] getResources(String locationPattern) throws IOException {
        Assert.notNull(locationPattern, "Location pattern must not be null");
        if (locationPattern.startsWith("classpath*:")) {	// 判断传过来的是否以 classpath*: 为前缀,就是解析xml文件里的配置
            return this.getPathMatcher().isPattern(locationPattern.substring("classpath*:".length())) ? this.findPathMatchingResources(locationPattern) : this.findAllClassPathResources(locationPattern.substring("classpath*:".length()));
        } else {
			// 判断是否是 war: 或者 */ ,   都不是
            int prefixEnd = locationPattern.startsWith("war:") ? locationPattern.indexOf("*/") + 1 : locationPattern.indexOf(58) + 1;
			// 既然都不是,所以使用后面判断代码,当前的这个值加载回来,获取当前资源路径,把资源路径放到Resource对象里面
            return this.getPathMatcher().isPattern(locationPattern.substring(prefixEnd)) ? this.findPathMatchingResources(locationPattern) : new Resource[]{this.getResourceLoader().getResource(locationPattern)};
        }
    }
	public Resource getResource(String location) {
        Assert.notNull(location, "Location must not be null");
        Iterator var2 = this.getProtocolResolvers().iterator();

        Resource resource;
        do {
            if (!var2.hasNext()) {
                if (location.startsWith("/")) {
                    return this.getResourceByPath(location);
                }

                if (location.startsWith("classpath:")) {
                    return new ClassPathResource(location.substring("classpath:".length()), this.getClassLoader());
                }

                try {
                    URL url = new URL(location);
                    return (Resource)(ResourceUtils.isFileURL(url) ? new FileUrlResource(url) : new UrlResource(url));
                } catch (MalformedURLException var5) {
					// 上面条件都不满足,所以会执行下面这行,通过路径返回Resource资源,点进去就可以看到处理过程了
                    return this.getResourceByPath(location);
                }
            }

            ProtocolResolver protocolResolver = (ProtocolResolver)var2.next();
            resource = protocolResolver.resolve(location, this);
        } while(resource == null);

        return resource;
    }

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通过路径获取到resources对象后,又调用了loadBeanDefinitions()重载方法,上面执行调用时穿入的参数是字符串,现在传入的参数是资源,执行到这个方法来看下面源码

loadBeanDefinitions
	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);
		}
		// 现在什么都没做,所以这个里面的ThreadLocal啥也没干,currentResources是空的
		Set<EncodedResource> currentResources = this.resourcesCurrentlyBeingLoaded.get();
		// 把encodedResource,也就是application.xml给加入到currentResources里面
		if (!currentResources.add(encodedResource)) {
			throw new BeanDefinitionStoreException(
					"Detected cyclic loading of " + encodedResource + " - check your import definitions!");
		}
		// 获取输入流对象,读取xml文件
		try (InputStream inputStream = encodedResource.getResource().getInputStream()) {
			InputSource inputSource = new InputSource(inputStream);
			if (encodedResource.getEncoding() != null) {
				inputSource.setEncoding(encodedResource.getEncoding());
			}
			// 这里开始真正执行,跳到下面的doLoadBeanDefinitions代码去看吧
			return doLoadBeanDefinitions(inputSource, encodedResource.getResource());
		}
		catch (IOException ex) {
			throw new BeanDefinitionStoreException(
					"IOException parsing XML document from " + encodedResource.getResource(), ex);
		}
		finally {
			currentResources.remove(encodedResource);
			if (currentResources.isEmpty()) {
				this.resourcesCurrentlyBeingLoaded.remove();
			}
		}
	}
doLoadBeanDefinitions()
	protected int doLoadBeanDefinitions(InputSource inputSource, Resource resource)
			throws BeanDefinitionStoreException {

		try {
			// 按照文档方式读取xml配置资源对象,主要是验证配置文件是否规范正确,先验证头信息,再验证其他配置信息,
			// 最后得到一个DocumentBuilder对象,可以通过这个对象过去到配置文件的属性值了
			Document doc = doLoadDocument(inputSource, resource);	// 具体是把xml解析一下成Document,它就是个字符串,可以自己点进去细看一下
			int count = registerBeanDefinitions(doc, resource);		// 点进去看源码,看下面代码
			if (logger.isDebugEnabled()) {
				logger.debug("Loaded " + count + " bean definitions from " + resource);
			}
			return count;	// 这里返回的是1,因为我只有一个person对象
		}
		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);
		}
	}

返回count为1,具体整个过程要下面的内容,到这个位置结束,就可以知道具体实现了

registerBeanDefinitions()
	/**
	 * Register the bean definitions contained in the given DOM document.
	 * 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 {
		// 创建一个BeanDefinitionDocumentReader,这个和前面的BeanDefinitionReader是不一样的,不要搞混了
		BeanDefinitionDocumentReader documentReader = createBeanDefinitionDocumentReader();
		// getRegistry()是获取BeanFactory,.getBeanDefinitionCount 是获取注册了多少个BeanDefinition
		int countBefore = getRegistry().getBeanDefinitionCount();	// 这个时候是0个,因为还没开始注册
		// 开始往里面注册,有个createReaderContext(resource),这次使用鼠标点进去,看下面的createReaderContext方法的源码
		// 看完createReaderContext(resource)后发现其实就是一个赋值的操作,然后看registerBeanDefinitions的方法
		documentReader.registerBeanDefinitions(doc, createReaderContext(resource));
		return getRegistry().getBeanDefinitionCount() - countBefore;
	}

createReaderContext:

	public XmlReaderContext createReaderContext(Resource resource) {
		// 查看XmlReaderContext类上面的注释,
		return new XmlReaderContext(resource, this.problemReporter, this.eventListener,
				// 调用的下面的getNamespaceHandlerResolver()方法
				this.sourceExtractor, this, getNamespaceHandlerResolver());
	}
	
	public NamespaceHandlerResolver getNamespaceHandlerResolver() {
		if (this.namespaceHandlerResolver == null) {
			// 调用了下面的createDefaultNamespaceHandlerResolver()方法
			this.namespaceHandlerResolver = createDefaultNamespaceHandlerResolver();
		}
		return this.namespaceHandlerResolver;
	}
	
	protected NamespaceHandlerResolver createDefaultNamespaceHandlerResolver() {
		ClassLoader cl = (getResourceLoader() != null ? getResourceLoader().getClassLoader() : getBeanClassLoader());
		// 点进去看DefaultNamespaceHandlerResolver的源码,这个就比较好玩了
		return new DefaultNamespaceHandlerResolver(cl);
	}

通过DefaultNamespaceHandlerResolver类上面的注释可以知道,接口的默认实现,是根据映射将命名空间uri解析为实现类,包含在映射文件中。

/**
 * Default implementation of the {@link NamespaceHandlerResolver} interface.
 * Resolves namespace URIs to implementation classes based on the mappings
 * contained in mapping file.
 *
 * <p>By default, this implementation looks for the mapping file at
 * {@code META-INF/spring.handlers}, but this can be changed using the
 * {@link #DefaultNamespaceHandlerResolver(ClassLoader, String)} constructor.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 2.0
 * @see NamespaceHandler
 * @see DefaultBeanDefinitionDocumentReader
 */
public class DefaultNamespaceHandlerResolver implements NamespaceHandlerResolver {

	/**
	 * The location to look for the mapping files. Can be present in multiple JAR files.
	 */
	 // 看这个"META-INF/spring.handlers"的值,
	public static final String DEFAULT_HANDLER_MAPPINGS_LOCATION = "META-INF/spring.handlers";
	
	。。。。。。

在这个META-INF/spring.handlers路径下找一找对应的spring.handlers文件里面都有很多对应的处理器,这些处理器就这么通过文件给拿过来的
image
这些就对应的xml配置文件里面的命名空间,所以xml文件的格式为什么要有固定的正确格式,不是白写的
image

registerBeanDefinitions:

	@Override
	public void registerBeanDefinitions(Document doc, XmlReaderContext readerContext) {
		this.readerContext = readerContext;
		// doc.getDocumentElement()是获取到xml文件里的父级标签
		doRegisterBeanDefinitions(doc.getDocumentElement());	// 所有带do的方法都是实际干活的方法,所以这个挺重要,看下面代码
	}
	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;
		// 开始赋值,这时候可以点进去看到 new了一个 BeanDefinitionParserDelegate,其实就是得到xml配置文件里对应的标签的值,如下图
		this.delegate = createDelegate(getReaderContext(), root, parent);

		if (this.delegate.isDefaultNamespace(root)) {	// 判断是否是默认的命名空间
			// PROFILE_ATTRIBUTE = "profile",PROFILE_ATTRIBUTE的值就是"profile",想想springboot时候,通过它来设置使用对应的环境切换,dev啦,sit啦
			String profileSpec = root.getAttribute(PROFILE_ATTRIBUTE);
			// 这里是同于空的,所以进不到这个判断里
			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);	// 这里什么都没做,可以点进去看看是个空的,没有具体的实现,所以就是让我们自己去扩展的
		parseBeanDefinitions(root, this.delegate);		// 这里是个核心,开始去解析BeanDefinitions了,看下面的源码
		postProcessXml(root);	// 这里也是空的,没有具体的实现,让自己去扩展用的

		this.delegate = parent;
	}

BeanDefinitionParserDelegate类:
image

BeanDefinitions()
	protected void parseBeanDefinitions(Element root, BeanDefinitionParserDelegate delegate) {
		if (delegate.isDefaultNamespace(root)) {
			// 获取beans里面所有标签
			NodeList nl = root.getChildNodes();
			for (int i = 0; i < nl.getLength(); i++) {
				Node node = nl.item(i);
				// 判断当前的一行是不是Element,这里要对应你写的xml配置文件,命名空间完后的内容
				if (node instanceof Element) {	// 如果这一行不为换行或注释,就会进来
					Element ele = (Element) node;
					// 这些都在for循环当中,也就是在循环遍历每一行,看是否是默认beans标签里面的子标签
					if (delegate.isDefaultNamespace(ele)) {		// 判断是否属于默认的,也就是<beans 标签里面的
						parseDefaultElement(ele, delegate);		// 我的xml配置文件里写的就是bean标签,所以就进来了,看下面的parseDefaultElement()方法代码
					}
					else {		// 如果这一行不是属于<beans 标签里面的,是其他定义的,就会到下面
						delegate.parseCustomElement(ele);
					}
				}
			}
		}
		else {
			delegate.parseCustomElement(root);
		}
	}

parseDefaultElement()方法:这个里面就比较熟悉了

	private void parseDefaultElement(Element ele, BeanDefinitionParserDelegate delegate) {
		if (delegate.nodeNameEquals(ele, IMPORT_ELEMENT)) {		// 判断是否是import标签
			importBeanDefinitionResource(ele);
		}
		else if (delegate.nodeNameEquals(ele, ALIAS_ELEMENT)) {		// 判断是否是alias标签
			processAliasRegistration(ele);
		}
		else if (delegate.nodeNameEquals(ele, BEAN_ELEMENT)) {		// 判断是否是bean标签,很显然是,就执行下面方法
			processBeanDefinition(ele, delegate);	// 看下面的方法源码
		}
		else if (delegate.nodeNameEquals(ele, NESTED_BEANS_ELEMENT)) {
			// recurse
			doRegisterBeanDefinitions(ele);
		}
	}
processBeanDefinition()
	protected void processBeanDefinition(Element ele, BeanDefinitionParserDelegate delegate) {
		// 调用了parseBeanDefinitionElement(ele),可以看下源码,最后调了parseBeanDefinitionElement()方法,看下面方法源码图
		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));
		}
	}

parseBeanDefinitionElement():
image
可以看到通过bean标签获取到了具体的属性值,因为containingBean是空的,所以又调用了checkNameUniqueness()方法,其实里面就是验证bean属性值的唯一性
parseBeanDefinitionElement()方法的源码:

	@Nullable
	public BeanDefinitionHolder parseBeanDefinitionElement(Element ele, @Nullable BeanDefinition containingBean) {
		String id = ele.getAttribute(ID_ATTRIBUTE);
		String nameAttr = ele.getAttribute(NAME_ATTRIBUTE);

		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;
		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);
		}
		// 开始执行parseBeanDefinitionElement方法,看下面方法的源代码吧。。
		AbstractBeanDefinition beanDefinition = parseBeanDefinitionElement(ele, beanName, containingBean);
		if (beanDefinition != null) {
			if (!StringUtils.hasText(beanName)) {	// 这里beanName是person属性值,所以不会进入这个判断
				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);
			// 返回一个BeanDefinitionHolder的对象
			return new BeanDefinitionHolder(beanDefinition, beanName, aliasesArray);
		}

		return null;
	}

parseBeanDefinitionElement():

	@Nullable
	public AbstractBeanDefinition parseBeanDefinitionElement(
			Element ele, String beanName, @Nullable BeanDefinition containingBean) {

		this.parseState.push(new BeanEntry(beanName));

		String className = null;
		if (ele.hasAttribute(CLASS_ATTRIBUTE)) {
			className = ele.getAttribute(CLASS_ATTRIBUTE).trim();
		}
		String parent = null;
		if (ele.hasAttribute(PARENT_ATTRIBUTE)) {
			parent = ele.getAttribute(PARENT_ATTRIBUTE);
		}

		try {
			AbstractBeanDefinition bd = createBeanDefinition(className, parent);
			// 这个方法解析判断是否是单例singleton的,是否是scope的等等,很多判断,可以自己点进去看看
			parseBeanDefinitionAttributes(ele, beanName, containingBean, bd);
			bd.setDescription(DomUtils.getChildElementValueByTagName(ele, DESCRIPTION_ELEMENT));
			// 这些方法都是在解析xml配置文件里的标签
			parseMetaElements(ele, bd);		// meta
			parseLookupOverrideSubElements(ele, bd.getMethodOverrides());	// lookup-method
			parseReplacedMethodSubElements(ele, bd.getMethodOverrides());	// replaced-method

			parseConstructorArgElements(ele, bd);		// constructor-arg
			parsePropertyElements(ele, bd);		// property
			parseQualifierElements(ele, bd);	// qualifier

			bd.setResource(this.readerContext.getResource());
			bd.setSource(extractSource(ele));

			return bd;		// 设置完以后返回
		}
		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;
	}

看到这里,以上就是doLoadBeanDefinitions()方法的实现了
然后就可以一直往上返回了,以上就是obtainFreshBeanFactory()大概的一个具体实现了

3、prepareBeanFactory(beanFactory);

这些方法不算太难,可以自己点进去看每个方法功能实现
主要就是往beanFactory里面注入一些属性或对象的值,方便以后调用

	/**
	 * Configure the factory's standard context characteristics,
	 * such as the context's ClassLoader and post-processors.
	 * @param beanFactory the BeanFactory to configure
	 */
	protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
		// Tell the internal bean factory to use the context's class loader etc.
		// beanFactory是刚上个方法创建的DefaultListableBeanFactory,然后把类加载器设置进去
		beanFactory.setBeanClassLoader(getClassLoader());
		// 设置SPEL表达式解析器
		beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
		// 存放一个资源编辑器,一般很少用
		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));

		// Configure the bean factory with context callbacks.
		// 加入一个增强器,就是实例化对象前的一个增强操作
		beanFactory.addBeanPostProcessor(new ApplicationContextAwareProcessor(this));
		// 把之前的一些ignoreDependency()方法执行的都给加进来
		beanFactory.ignoreDependencyInterface(EnvironmentAware.class);
		beanFactory.ignoreDependencyInterface(EmbeddedValueResolverAware.class);
		beanFactory.ignoreDependencyInterface(ResourceLoaderAware.class);
		beanFactory.ignoreDependencyInterface(ApplicationEventPublisherAware.class);
		beanFactory.ignoreDependencyInterface(MessageSourceAware.class);
		beanFactory.ignoreDependencyInterface(ApplicationContextAware.class);

		// BeanFactory interface not registered as resolvable type in a plain factory.
		// MessageSource registered (and found for autowiring) as a bean.
		// 必须要注入进入的bean对象
		beanFactory.registerResolvableDependency(BeanFactory.class, beanFactory);
		beanFactory.registerResolvableDependency(ResourceLoader.class, this);
		beanFactory.registerResolvableDependency(ApplicationEventPublisher.class, this);
		beanFactory.registerResolvableDependency(ApplicationContext.class, this);

		// Register early post-processor for detecting inner beans as ApplicationListeners.
		// 又有一个addBeanPostProcessor,一个广播器
		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(this));

		// Detect a LoadTimeWeaver and prepare for weaving, if found.
		if (beanFactory.containsBean(LOAD_TIME_WEAVER_BEAN_NAME)) {
			beanFactory.addBeanPostProcessor(new LoadTimeWeaverAwareProcessor(beanFactory));
			// Set a temporary ClassLoader for type matching.
			beanFactory.setTempClassLoader(new ContextTypeMatchClassLoader(beanFactory.getBeanClassLoader()));
		}

		// Register default environment beans.
		if (!beanFactory.containsLocalBean(ENVIRONMENT_BEAN_NAME)) {	// 是否包含loadTimeWeaver属性值
			beanFactory.registerSingleton(ENVIRONMENT_BEAN_NAME, getEnvironment());
		}
		if (!beanFactory.containsLocalBean(SYSTEM_PROPERTIES_BEAN_NAME)) {	// 是否包含environment属性值,没有的话把它放进来
			beanFactory.registerSingleton(SYSTEM_PROPERTIES_BEAN_NAME, getEnvironment().getSystemProperties());
		}
		if (!beanFactory.containsLocalBean(SYSTEM_ENVIRONMENT_BEAN_NAME)) {	// 是否包含systemProperties属性,没有的话也给放进来
			beanFactory.registerSingleton(SYSTEM_ENVIRONMENT_BEAN_NAME, getEnvironment().getSystemEnvironment());
		}
	}

4、postProcessBeanFactory(beanFactory);

发现postProcessBeanFactory()的方法是空的,所以留给子类实现,可以让我们自己去扩展实现一些东西

	/**
	 * Modify the application context's internal bean factory after its standard
	 * initialization. All bean definitions will have been loaded, but no beans
	 * will have been instantiated yet. This allows for registering special
	 * BeanPostProcessors etc in certain ApplicationContext implementations.
	 * @param beanFactory the bean factory used by the application context
	 */
	protected void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) {
	}

5、invokeBeanFactoryPostProcessors(beanFactory);

	protected void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory) {
		// 最核心的就是调用了invokeBeanFactoryPostProcessors方法,看下面源码,这个方法有点多
		// getBeanFactoryPostProcessors()返回的是空的,所以可以先不用看
		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()));
		}
	}

invokeBeanFactoryPostProcessors()

	public static void invokeBeanFactoryPostProcessors(
			ConfigurableListableBeanFactory beanFactory, List<BeanFactoryPostProcessor> beanFactoryPostProcessors) {

		// Invoke BeanDefinitionRegistryPostProcessors first, if any.
		Set<String> processedBeans = new HashSet<>();	// 存放已经执行过的processe,避免重复执行

		// 判断是否是BeanDefinitionRegistry的子类,看下图,DefaultListableBeanFactory就是BeanDefinitionRegistry的子类
		if (beanFactory instanceof BeanDefinitionRegistry) {
			BeanDefinitionRegistry registry = (BeanDefinitionRegistry) beanFactory;
			// 定义两个集合,BeanDefinitionRegistryPostProcessor是BeanFactoryPostProcessor的子类,可以自己看下关系图
			List<BeanFactoryPostProcessor> regularPostProcessors = new ArrayList<>();
			List<BeanDefinitionRegistryPostProcessor> registryProcessors = new ArrayList<>();

			// 这个是空的,所以就不会进入循环
			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.
			List<BeanDefinitionRegistryPostProcessor> currentRegistryProcessors = new ArrayList<>();

			// First, invoke the BeanDefinitionRegistryPostProcessors that implement PriorityOrdered.
			// 进入看getBeanNamesForType源码,在下面有
			String[] postProcessorNames =
					beanFactory.getBeanNamesForType(BeanDefinitionRegistryPostProcessor.class, true, false);
			for (String ppName : postProcessorNames) {		// 为空的,进不到循环里
				if (beanFactory.isTypeMatch(ppName, PriorityOrdered.class)) {	// 主要是判断类型是否匹配
					currentRegistryProcessors.add(beanFactory.getBean(ppName, BeanDefinitionRegistryPostProcessor.class));
					processedBeans.add(ppName);
				}
			}
			sortPostProcessors(currentRegistryProcessors, beanFactory);
			registryProcessors.addAll(currentRegistryProcessors);	// 往集合里添加,上面定义的集合
			// 执行上面postProcessorNames循环里是否有对应添加到currentRegistryProcessors的BeanDefinition
			invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
			currentRegistryProcessors.clear();	// 上面一行代码执行完后,给清掉

			// Next, invoke the BeanDefinitionRegistryPostProcessors that implement Ordered.
			// 这里开始和上面一段代码很像
			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.
			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();
			}
			// 上面等于经历了3次过滤
			// Now, invoke the postProcessBeanFactory callback of all processors handled so far.
			// 这两个方法挺麻烦的
			invokeBeanFactoryPostProcessors(registryProcessors, beanFactory);
			invokeBeanFactoryPostProcessors(regularPostProcessors, beanFactory);
		}

		else {
			// Invoke factory processors registered with the context instance.
			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.
		// 定义3个集合
		List<BeanFactoryPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		for (String ppName : postProcessorNames) {	// 开始在循环里做判断
			if (processedBeans.contains(ppName)) {	// 分配判断是否是3种PostProcessor
				// 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);	// 这个还是自己点进去看了大概的逻辑,不难

		// Next, invoke the BeanFactoryPostProcessors that implement Ordered.
		// 有orderedPostProcessors的话,添加进order的集合
		List<BeanFactoryPostProcessor> orderedPostProcessors = new ArrayList<>(orderedPostProcessorNames.size());
		for (String postProcessorName : orderedPostProcessorNames) {
			orderedPostProcessors.add(beanFactory.getBean(postProcessorName, BeanFactoryPostProcessor.class));
		}
		sortPostProcessors(orderedPostProcessors, beanFactory);
		invokeBeanFactoryPostProcessors(orderedPostProcessors, beanFactory);	// 这个不难,自己大概看一下

		// Finally, invoke all other BeanFactoryPostProcessors.
		List<BeanFactoryPostProcessor> nonOrderedPostProcessors = new ArrayList<>(nonOrderedPostProcessorNames.size());
		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();
	}

image

getBeanNamesForType()

image
看这个doGetBeanNamesForType的方法代码吧

	private String[] doGetBeanNamesForType(ResolvableType type, boolean includeNonSingletons, boolean allowEagerInit) {
		List<String> result = new ArrayList<>();

		// Check all bean definitions.
		for (String beanName : this.beanDefinitionNames) {		// 取出bean对象名称
			// Only consider bean as eligible if the bean name is not defined as alias for some other bean.
			if (!isAlias(beanName)) {	// 如果不是别名的话
				try {
					// 获取合并本地的BeanDefinition?点进入看下可以知道,返回了一个从根上来的BeanDefinition,不用过于仔细看,太多了,知道就行
					RootBeanDefinition mbd = getMergedLocalBeanDefinition(beanName);
					// Only check bean definition if it is complete.得到RootBeanDefinition后,进入到判断里了
					if (!mbd.isAbstract() && (allowEagerInit ||
							(mbd.hasBeanClass() || !mbd.isLazyInit() || isAllowEagerClassLoading()) &&
									!requiresEagerInitForType(mbd.getFactoryBeanName()))) {
						boolean isFactoryBean = isFactoryBean(beanName, mbd);	// 显然不是FactoryBean对象
						BeanDefinitionHolder dbd = mbd.getDecoratedDefinition();
						boolean matchFound = false;
						boolean allowFactoryBeanInit = (allowEagerInit || containsSingleton(beanName));
						boolean isNonLazyDecorated = (dbd != null && !mbd.isLazyInit());
						if (!isFactoryBean) {
							if (includeNonSingletons || isSingleton(beanName, mbd, dbd)) {
								// 判断类型是否是匹配的,显然不是
								matchFound = isTypeMatch(beanName, type, allowFactoryBeanInit);
							}
						}
						else {
							if (includeNonSingletons || isNonLazyDecorated ||
									(allowFactoryBeanInit && isSingleton(beanName, mbd, dbd))) {
								matchFound = isTypeMatch(beanName, type, allowFactoryBeanInit);
							}
							if (!matchFound) {
								// In case of FactoryBean, try to match FactoryBean instance itself next.
								beanName = FACTORY_BEAN_PREFIX + beanName;
								matchFound = isTypeMatch(beanName, type, allowFactoryBeanInit);
							}
						}
						if (matchFound) {	// matchFound为false
							result.add(beanName);
						}
					}
				}
				catch (CannotLoadBeanClassException | BeanDefinitionStoreException ex) {
					if (allowEagerInit) {
						throw ex;
					}
					// Probably a placeholder: let's ignore it for type matching purposes.
					LogMessage message = (ex instanceof CannotLoadBeanClassException ?
							LogMessage.format("Ignoring bean class loading failure for bean '%s'", beanName) :
							LogMessage.format("Ignoring unresolvable metadata in bean definition '%s'", beanName));
					logger.trace(message, ex);
					// Register exception, in case the bean was accidentally unresolvable.
					onSuppressedException(ex);
				}
				catch (NoSuchBeanDefinitionException ex) {
					// Bean definition got removed while we were iterating -> ignore.
				}
			}
		}

		// Check manually registered singletons too.
		for (String beanName : this.manualSingletonNames) {		// 这些循环里面的判断都进不去,直接跳到最后返回
			try {
				// In case of FactoryBean, match object created by FactoryBean.
				if (isFactoryBean(beanName)) {
					if ((includeNonSingletons || isSingleton(beanName)) && isTypeMatch(beanName, type)) {
						result.add(beanName);
						// Match found for this bean: do not match FactoryBean itself anymore.
						continue;
					}
					// In case of FactoryBean, try to match FactoryBean itself next.
					beanName = FACTORY_BEAN_PREFIX + beanName;
				}
				// Match raw bean instance (might be raw FactoryBean).
				if (isTypeMatch(beanName, type)) {
					result.add(beanName);
				}
			}
			catch (NoSuchBeanDefinitionException ex) {
				// Shouldn't happen - probably a result of circular reference resolution...
				logger.trace(LogMessage.format(
						"Failed to check manually registered singleton with name '%s'", beanName), ex);
			}
		}

		return StringUtils.toStringArray(result);
	}

返回到getBeanNamesForType方法里面的doGetBeanNamesForType调用,这一行也是返回的,返回到了上面代码里的
invokeBeanFactoryPostProcessors方法里面的beanFactory.getBeanNamesForType()调用

6、registerBeanPostProcessors(beanFactory);

image
registerBeanPostProcessors里面又调用了registerBeanPostProcessors,看这个调用的方法代码

registerBeanPostProcessors()

	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.
		int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
		beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));	// 完成一个加入其他操作的功能,aop的思想

		// Separate between BeanPostProcessors that implement PriorityOrdered,
		// Ordered, and the rest.
		// 定义了4个集合,然后循环遍历,判断给不同集合放值
		List<BeanPostProcessor> priorityOrderedPostProcessors = new ArrayList<>();
		List<BeanPostProcessor> internalPostProcessors = new ArrayList<>();
		List<String> orderedPostProcessorNames = new ArrayList<>();
		List<String> nonOrderedPostProcessorNames = new ArrayList<>();
		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<>(orderedPostProcessorNames.size());
		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<>(nonOrderedPostProcessorNames.size());
		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.
		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).
		// 最后完成注册进去
		beanFactory.addBeanPostProcessor(new ApplicationListenerDetector(applicationContext));
	}

7、initMessageSource();

这个方法比较简单,主要完成国际化的消息通知

	protected void initMessageSource() {
		// 获取BeanFactory
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();
		if (beanFactory.containsLocalBean(MESSAGE_SOURCE_BEAN_NAME)) {	// 是否包含"messageSource"
			this.messageSource = beanFactory.getBean(MESSAGE_SOURCE_BEAN_NAME, MessageSource.class);
			// Make MessageSource aware of parent MessageSource.
			if (this.parent != null && this.messageSource instanceof HierarchicalMessageSource) {
				HierarchicalMessageSource hms = (HierarchicalMessageSource) this.messageSource;
				if (hms.getParentMessageSource() == null) {
					// Only set parent context as parent MessageSource if no parent MessageSource
					// registered already.
					hms.setParentMessageSource(getInternalParentMessageSource());
				}
			}
			if (logger.isTraceEnabled()) {
				logger.trace("Using MessageSource [" + this.messageSource + "]");
			}
		}
		else {	// 跳到这个分支
			// Use empty MessageSource to be able to accept getMessage calls.
			DelegatingMessageSource dms = new DelegatingMessageSource();	// 创建新的messageSource
			dms.setParentMessageSource(getInternalParentMessageSource());	// 添加到父类messageSource
			this.messageSource = dms;
			beanFactory.registerSingleton(MESSAGE_SOURCE_BEAN_NAME, this.messageSource);	// 注册成singleton对象
			if (logger.isTraceEnabled()) {
				logger.trace("No '" + MESSAGE_SOURCE_BEAN_NAME + "' bean, using [" + this.messageSource + "]");
			}
		}
	}

8、initApplicationEventMulticaster();

初始化事件监听器

	protected void initApplicationEventMulticaster() {
		ConfigurableListableBeanFactory beanFactory = getBeanFactory();		// 获取beanFactory
		if (beanFactory.containsLocalBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME)) {	// 是否包含applicationEventMulticaster
			this.applicationEventMulticaster =
					beanFactory.getBean(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, ApplicationEventMulticaster.class);
			if (logger.isTraceEnabled()) {
				logger.trace("Using ApplicationEventMulticaster [" + this.applicationEventMulticaster + "]");
			}
		}
		else {		// 不包含,走下面
			// 创建一个新的
			this.applicationEventMulticaster = new SimpleApplicationEventMulticaster(beanFactory);
			// 注册事件监听器
			beanFactory.registerSingleton(APPLICATION_EVENT_MULTICASTER_BEAN_NAME, this.applicationEventMulticaster);
			if (logger.isTraceEnabled()) {
				logger.trace("No '" + APPLICATION_EVENT_MULTICASTER_BEAN_NAME + "' bean, using " +
						"[" + this.applicationEventMulticaster.getClass().getSimpleName() + "]");
			}
		}
	}

9、onRefresh();

发现里面什么都没做,那就是留给子类做具体实现的

	/**
	 * Template method which can be overridden to add context-specific refresh work.
	 * Called on initialization of special beans, before instantiation of singletons.
	 * <p>This implementation is empty.
	 * @throws BeansException in case of errors
	 * @see #refresh()
	 */
	protected void onRefresh() throws BeansException {
		// For subclasses: do nothing by default.
	}

10、registerListeners();

上面使用了initApplicationEventMulticaster()方法,所以这时候要注册一些事件监听器
这里因为只有一个bean对象person对象,别的啥也没有,所以这个方法等于没执行

	protected void registerListeners() {
		// Register statically specified listeners first.
		for (ApplicationListener<?> listener : getApplicationListeners()) {
			getApplicationEventMulticaster().addApplicationListener(listener);
		}

		// Do not initialize FactoryBeans here: We need to leave all regular beans
		// uninitialized to let post-processors apply to them!
		String[] listenerBeanNames = getBeanNamesForType(ApplicationListener.class, true, false);
		for (String listenerBeanName : listenerBeanNames) {
			getApplicationEventMulticaster().addApplicationListenerBean(listenerBeanName);
		}

		// Publish early application events now that we finally have a multicaster...
		Set<ApplicationEvent> earlyEventsToProcess = this.earlyApplicationEvents;
		this.earlyApplicationEvents = null;
		if (!CollectionUtils.isEmpty(earlyEventsToProcess)) {
			for (ApplicationEvent earlyEvent : earlyEventsToProcess) {
				getApplicationEventMulticaster().multicastEvent(earlyEvent);
			}
		}
	}

11、finishBeanFactoryInitialization(beanFactory);

实例化所有单例对象,这个方法很重要

	protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
		// Initialize conversion service for this context.
		// 是否包含conversionService对象,这时候没有
		if (beanFactory.containsBean(CONVERSION_SERVICE_BEAN_NAME) &&
				beanFactory.isTypeMatch(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class)) {
			beanFactory.setConversionService(
					beanFactory.getBean(CONVERSION_SERVICE_BEAN_NAME, ConversionService.class));
		}

		// Register a default embedded value resolver if no bean post-processor
		// (such as a PropertyPlaceholderConfigurer bean) registered any before:
		// at this point, primarily for resolution in annotation attribute values.
		if (!beanFactory.hasEmbeddedValueResolver()) {	// 这里判断没有的话,就给加进来
			beanFactory.addEmbeddedValueResolver(strVal -> getEnvironment().resolvePlaceholders(strVal));
		}

		// Initialize LoadTimeWeaverAware beans early to allow for registering their transformers early.
		String[] weaverAwareNames = beanFactory.getBeanNamesForType(LoadTimeWeaverAware.class, false, false);
		for (String weaverAwareName : weaverAwareNames) {	// 为空,所以没有进来循环
			getBean(weaverAwareName);
		}

		// Stop using the temporary ClassLoader for type matching.
		beanFactory.setTempClassLoader(null);	// 设置空的临时加载器

		// Allow for caching all bean definition metadata, not expecting further changes.
		beanFactory.freezeConfiguration();		// 不允许更改bean的元素

		// Instantiate all remaining (non-lazy-init) singletons.
		beanFactory.preInstantiateSingletons();		// 这里很重要,开始进行实例化所有的单例对象,看下面源码
	}

preInstantiateSingletons()

	@Override
	public void preInstantiateSingletons() throws BeansException {
		if (logger.isTraceEnabled()) {
			logger.trace("Pre-instantiating singletons in " + this);
		}

		// Iterate over a copy to allow for init methods which in turn register new bean definitions.
		// While this may not be part of the regular factory bootstrap, it does otherwise work fine.
		List<String> beanNames = new ArrayList<>(this.beanDefinitionNames);		// 把bean的名称拿过来

		// Trigger initialization of all non-lazy singleton beans...
		for (String beanName : beanNames) {
			RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);		// 这个方法前面很早时候有遇到过
			// 判断不是抽象的、懒加载的,是单例的
			if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
				if (isFactoryBean(beanName)) {	// 不是FactoryBean,所以这里不会进来
					Object bean = getBean(FACTORY_BEAN_PREFIX + beanName);
					if (bean instanceof FactoryBean) {
						FactoryBean<?> factory = (FactoryBean<?>) bean;
						boolean isEagerInit;
						if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
							isEagerInit = AccessController.doPrivileged(
									(PrivilegedAction<Boolean>) ((SmartFactoryBean<?>) factory)::isEagerInit,
									getAccessControlContext());
						}
						else {
							isEagerInit = (factory instanceof SmartFactoryBean &&
									((SmartFactoryBean<?>) factory).isEagerInit());
						}
						if (isEagerInit) {
							getBean(beanName);
						}
					}
				}
				else {	// 跳到这里来
					getBean(beanName);	// 这里方法是个难点,看下图,调用了doGetBean方法
				}
			}
		}

		// Trigger post-initialization callback for all applicable beans...
		for (String beanName : beanNames) {		// 循环遍历所有bean对象,这里不是很难
			Object singletonInstance = getSingleton(beanName);
			if (singletonInstance instanceof SmartInitializingSingleton) {
				SmartInitializingSingleton smartSingleton = (SmartInitializingSingleton) singletonInstance;
				if (System.getSecurityManager() != null) {
					AccessController.doPrivileged((PrivilegedAction<Object>) () -> {
						smartSingleton.afterSingletonsInstantiated();
						return null;
					}, getAccessControlContext());
				}
				else {
					smartSingleton.afterSingletonsInstantiated();
				}
			}
		}
	}

image
这个doGetBean方法实在太长了,自己debug时候看看吧
image
下面还有方法的其他代码,太多了,自己好好看看吧
里面有个createBean()方法,调用的doCreateBean方法,里面使用了反射

12、finishRefresh();

	protected void finishRefresh() {
		// Clear context-level resource caches (such as ASM metadata from scanning).
		clearResourceCaches();		// 清楚缓存

		// Initialize lifecycle processor for this context.
		initLifecycleProcessor();	// 初始化生命周期操作

		// Propagate refresh to lifecycle processor first.
		getLifecycleProcessor().onRefresh();	// 刷新生命周期

		// Publish the final event.
		publishEvent(new ContextRefreshedEvent(this));		// 刷新对应的事件

		// Participate in LiveBeansView MBean, if active.
		LiveBeansView.registerApplicationContext(this);		// 注册ApplicationContext
	}

13、resetCommonCaches();

重置公共缓存

posted @ 2022-11-25 16:26  aBiu--  阅读(131)  评论(0编辑  收藏  举报