IOC容器啟動過程

1. 資源定位(classpath,filesystem等)
2. 載入，將bean定義轉換為內部資料結構BeanDefintion
3. 向IOC容器註冊bean

資源定位

定位配置檔案，通過BeadDefinetionReader讀入配置

refresh方法實現

IOC容器啟動方法是ConfigurableApplicationContext中定義的refresh方法，在AbstractApplicationContext中實現

//準備階段做的是：標記容器為active狀態，以及檢查當前的執行環境，比如使用log4j，還是jdklog等
prepareRefresh();

//建立beanfactory， 定位資源，載入，裝配beandefinetion
 

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

//初始化beanfactory, 設定contex的classloader

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

try {
    //在基本的初始化之後，對beanfactory做一些修改
    // Allows post-processing of the bean factory in context subclasses.
 

    postProcessBeanFactory(beanFactory);

    //呼叫beanfactory後處理器
    // Invoke factory processors registered as beans in the context.
    invokeBeanFactoryPostProcessors(beanFactory);

    //註冊bean後處理器
    // Register bean processors that intercept bean creation.
    registerBeanPostProcessors(beanFactory);

    //初始化訊息資源，國際化
 

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

    // Initialize event multicaster for this context.
    initApplicationEventMulticaster();
    //在例項化bean之前，做一些工作
    // Initialize other special beans in specific context subclasses.
    onRefresh();

    //註冊 ApplicationListener監聽器
    // Check for listener beans and register them.
    registerListeners();

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

    //釋出bean正常響應事件，初始化bean生命週期處理器
    // Last step: publish corresponding event.
    finishRefresh();
}

BeanDefinetion

BeanDefinetion是定義bean的抽象

向IOC容器註冊BeanDefinetion

用HashMap維護BeanDefinetion, beanName作為key,BeanDefintion作為value
如果有同名key，如果有配置overridebean，那就覆蓋，沒有就報錯
populateBean方法完成bean的依賴注入

依賴注入

// Instantiate all remaining (non-lazy-init) singletons.
//在refresh方法中初始化非懶載入的bean
finishBeanFactoryInitialization(beanFactory);