ApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");

        PersonService personService = (PersonServiceBean)context.getBean("personService");

        personService.add();

//ClassPathXmlApplicationContext的另一个构造函数

public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh, ApplicationContext parent)

            throws BeansException {

        super(parent);

        setConfigLocations(configLocations);

        if (refresh) {

            refresh();

        }

    }

//ClassPathXmlApplicationContext继承了AbstractRefreshableConfigApplicationContext，因此在是AbstractRefreshableConfigApplicationContext里设置配置文件路径

//设置需要读取的配置文件

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;

        }

    }

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) {

                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;

            }

        }

    }

//得到BeanFactory

    protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {

        refreshBeanFactory();

        ConfigurableListableBeanFactory beanFactory = getBeanFactory();

        if (logger.isDebugEnabled()) {

            logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);

        }

        return beanFactory;

    }

@Override

    protected final void refreshBeanFactory() throws BeansException {

        if (hasBeanFactory()) {

            destroyBeans();

            closeBeanFactory();

        }

        try {

            DefaultListableBeanFactory beanFactory = createBeanFactory();//创建BeanFactory

            beanFactory.setSerializationId(getId());

            customizeBeanFactory(beanFactory);

            loadBeanDefinitions(beanFactory);//加载配置并解析配置文件

            synchronized (this.beanFactoryMonitor) {

                this.beanFactory = beanFactory;

            }

        }

        catch (IOException ex) {

            throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);

        }

    }

    @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);// 加载BeanDefinition

    }