第一步：new一个ClassPathXmlApplicationContext对象

ClassPathXmlApplicationContext xmlContext = new ClassPathXmlApplicationContext("mylearn.xml");

第二步：调用构造方法

public ClassPathXmlApplicationContext(String configLocation) throws BeansException {this(new String[] {configLocation}, true, null);
}

public ClassPathXmlApplicationContext(String[] configLocations, boolean refresh, @Nullable ApplicationContext parent)throws BeansException {super(parent);//设置上下文的配置路径setConfigLocations(configLocations);if (refresh) {//刷新上下文refresh();}
}

public void setConfigLocations(@Nullable 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;}
}

@Override
public void refresh() throws BeansException, IllegalStateException {synchronized (this.startupShutdownMonitor) {StartupStep contextRefresh = this.applicationStartup.start("spring.context.refresh");// 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);StartupStep beanPostProcess = this.applicationStartup.start("spring.context.beans.post-process");// Invoke factory processors registered as beans in the context.invokeBeanFactoryPostProcessors(beanFactory);// Register bean processors that intercept bean creation.registerBeanPostProcessors(beanFactory);beanPostProcess.end();// 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();contextRefresh.end();}}
}

第三步：调用抽象父类AbstractXmlApplicationContext

public AbstractXmlApplicationContext(@Nullable ApplicationContext parent) {super(parent);
}

第四步：调用抽象父类AbstractRefreshableConfigApplicationContext

public AbstractRefreshableConfigApplicationContext(@Nullable ApplicationContext parent) {super(parent);
}

第五步：调用抽象父类AbstractRefreshableApplicationContext

public AbstractRefreshableConfigApplicationContext(@Nullable ApplicationContext parent) {super(parent);
}

第六步：调用抽象父类AbstractApplicationContext

public AbstractApplicationContext(@Nullable ApplicationContext parent) {this();setParent(parent);
}

public AbstractApplicationContext() {this.resourcePatternResolver = getResourcePatternResolver();
}

获取接口解析器 ResourcePatternResolver

protected ResourcePatternResolver getResourcePatternResolver() {return new PathMatchingResourcePatternResolver(this);
}

第七步：设置应用上下文接口ApplicationContext

@Override
public void setParent(@Nullable ApplicationContext parent) {this.parent = parent;if (parent != null) {Environment parentEnvironment = parent.getEnvironment();if (parentEnvironment instanceof ConfigurableEnvironment) {getEnvironment().merge((ConfigurableEnvironment) parentEnvironment);}}
}