package com.test.spring;

public class Coffee {

    public Coffee() {
        System.out.println("正在初始化bean !!!調(diào)用無參構(gòu)造函數(shù)");
    }

}

<bean name="coffee" class="com.test.spring.Coffee"/>

@Test
public void testLazyInit() {

    System.out.println("開始初始化Spring容器 ");
    
    // 非懶加載的bean會(huì)在容器初始化時(shí)進(jìn)行bean的初始化，后面會(huì)拿Spring啟動(dòng)時(shí)的源碼進(jìn)行分析
    ApplicationContext context = new ClassPathXmlApplicationContext("spring-beans.xml");
    
   // 非懶加載的bean 的構(gòu)造函數(shù)會(huì)在這個(gè)位置打印
   System.out.println("Spring容器初始化完畢");

   System.out.println("開始從容器中獲取Bean");

   Coffee coffee = context.getBean("coffee", Coffee.class);

   System.out.println("獲取完畢  bean :" + coffee);
}

<bean name="coffee" class="com.test.spring.Coffee" lazy-init="true" />

@Test
public void testLazyInit() {

    System.out.println("開始初始化Spring容器 ");
    
    // 在初始化容器階段不會(huì)對(duì)懶加載的bean進(jìn)行初始化
    ApplicationContext context = new ClassPathXmlApplicationContext("spring-beans.xml");

    System.out.println("Spring容器初始化完畢");

    System.out.println("開始從容器中獲取Bean");
    
    // 在這一階段會(huì)對(duì)懶加載的bean進(jìn)行初始化
    Coffee coffee = context.getBean("coffee", Coffee.class);

    System.out.println("獲取完畢  bean :" + coffee);


}

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

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

    super(parent);
    setConfigLocations(configLocations);
    if (refresh) {
        // Spring ioc 啟動(dòng)入口 了解了refresh 就了解了ioc
        refresh();
    }
}

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

        // 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);
            // Instantiate all remaining (non-lazy-init) singletons.
            // 初始化所有非 懶加載的bean?。。?！
            finishBeanFactoryInitialization(beanFactory);

            // Last step: publish corresponding event.
            finishRefresh();
        }
 }

public void preInstantiateSingletons() throws BeansException {
   // 所有beanDefinition集合
   List<String> beanNames = new ArrayList<String>(this.beanDefinitionNames);
   // 觸發(fā)所有非懶加載單例bean的初始化
   for (String beanName : beanNames) {
       // 獲取bean 定義
      RootBeanDefinition bd = getMergedLocalBeanDefinition(beanName);
      // 判斷是否是懶加載單例bean，如果是單例的并且不是懶加載的則在Spring 容器
      if (!bd.isAbstract() && bd.isSingleton() && !bd.isLazyInit()) {
          // 判斷是否是FactoryBean
         if (isFactoryBean(beanName)) {
                final FactoryBean<?> factory = (FactoryBean<?>) getBean(FACTORY_BEAN_PREFIX + beanName);
                boolean isEagerInit;
                if (System.getSecurityManager() != null && factory instanceof SmartFactoryBean) {
                   isEagerInit = AccessController.doPrivileged(new PrivilegedAction<Boolean>() {
                      @Override
                      public Boolean run() {
                         return ((SmartFactoryBean<?>) factory).isEagerInit();
                      }
                   }, getAccessControlContext());
                }
         }else {
             // 如果是普通bean則進(jìn)行初始化依賴注入，此 getBean(beanName)接下來觸發(fā)的邏輯跟
             // context.getBean("beanName") 所觸發(fā)的邏輯是一樣的
            getBean(beanName);
         }
      }
   }
}

@Override
public Object getBean(String name) throws BeansException {   
    return doGetBean(name, null, null, false);
}

// 容器啟動(dòng)初始化 會(huì)初始化并依賴注入非懶加載的bean
ApplicationContext context = new ClassPathXmlApplicationContext("spring-beans.xml");

// lazy-init bean會(huì)進(jìn)行第一次初始化并依賴注入  其他的會(huì)從緩存里取
Coffee coffee = context.getBean("coffee", Coffee.class);