阿里云Java 杂谈

Springboot启动过程

2019-03-14  本文已影响27人  WANGGGGG

看了一整天的springboot的源码,头都有点疼了,稍微梳理了一下流程:


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简单看完一遍之后没找到它在哪里加载了配置信息,Bean对象等,然后又看了一遍,发现在AbstractApplicationContext的refresh中:

public void refresh() throws BeansException, IllegalStateException {
        //它是上了同步锁的,不能多个线程同时进行
        synchronized (this.startupShutdownMonitor) {
            //设置spring容器的启动时间,撤销关闭状态,开启活跃状态,初始化属性源信息,验证环境信息中必须存在的配置,不存在就抛出异常.
            prepareRefresh();
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();         
           //设置Bean的类加载器,Bean表达式解析器;添加属性编辑注册器 
          //添加PostProcessor,注册一些依赖等
            prepareBeanFactory(beanFactory);
            try {
                // Allows post-processing of the bean factory in context subclasses.
                postProcessBeanFactory(beanFactory);
                //从context中获取bean信息,并委托BeanFactory注册Bean.
                invokeBeanFactoryPostProcessors(beanFactory);

                // Register bean processors that intercept bean creation.
                registerBeanPostProcessors(beanFactory);

                //初始化国际化资源信息.
                initMessageSource();

                //初始化广播器,可以用广播发布事件.
                initApplicationEventMulticaster();

                //由子类自己实现,不同的容器做不同的事情.
                onRefresh();

                //检查并注册监听器.
                registerListeners();

                //实例化BeanFactory中已经被注册的但未被实例化的所有实例,除了标注了懒加载的.
                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();
            }
        }
    }

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