代码

ClassPathXmlApplicationContext ac = new ClassPathXmlApplicationContext("spring-context.xml");

类图

继承的类图，忽略实现的接口

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时序图

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详细步骤

1. new ClassPathXmlApplicationContext(),初始化ClassPathXmlApplicationContext

   public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh, ApplicationContext parent)
           throws BeansException {
       super(parent);
       setConfigLocations(configLocations);
       if (refresh) {
           refresh();
       }
   }
   

2. 调用AbstractRefreshableConfigApplicationContext的setConfigLocations(configLocations),设置xml文件路径

   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;
       }
   }
   

3. 调用AbstractApplicationContext的refresh(),这个方法内容太多，对于ClassPathXmlApplicationContext加载bean，只需了解它的obtainFreshBeanFactory方法。
4. obtainFreshBeanFactory方法,获取BeanFactory。
5. 调用AbstractRefreshableApplicationContext的refreshBeanFactory方法

   protected final void refreshBeanFactory() throws BeansException {
       if (hasBeanFactory()) {
           destroyBeans();
           closeBeanFactory();
       }
       try {
           //创建BeanFactory
           DefaultListableBeanFactory beanFactory = createBeanFactory();
           beanFactory.setSerializationId(getId());
           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);
       }
   }
   

   protected DefaultListableBeanFactory createBeanFactory() {
       return new DefaultListableBeanFactory(getInternalParentBeanFactory());
   }
   

6. 调用AbstractXmlApplicationContext的loadBeanDefinitions方法，加载bean

   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);
   }
   

7. 加载bean主要是对配置文件的读取，并将配置中的bean读取到DefaultListableBeanFactory中