一次ApplicationContext的实例化过程

好记性不如烂笔头。记一下对ApplicationContext实例化的过程的吧。

代码：

ApplicationContext context =
        new ClassPathXmlApplicationContext("applicationContext.xml");

首先进入的代码是：

    static {
        ContextClosedEvent.class.getName();
    }

这个代码块在AbstractApplicationContext里，是ClassPathXmlApplicationContext的父类，所以静态代码块先运行。（所以这句代码的作用是啥呢？求大佬指导）

进入代码：

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

之后调用本类的另一个构造方法

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

    }

 

调用父类AbstractXmlApplicationContext构造方法

调用父类AbstractRefreshableConfigApplicationContext构造方法

调用父类AbstractRefreshableApplicationContext构造方法

调用父类AbstractApplicationContext构造方法

    public AbstractApplicationContext(ApplicationContext parent) {
        this();//调用AbstractApplicationContext的无参构造方法
        this.setParent(parent);
    }

    public AbstractApplicationContext() {
        this.logger = LogFactory.getLog(this.getClass());
        this.id = ObjectUtils.identityToString(this);
//这个应用上下文的ID
        this.displayName = ObjectUtils.identityToString(this);
//这个应用上下文（ApplicationContext）的名称，由这个类的 类名+ @ + 这个context对象的hash值 组成。
        this.beanFactoryPostProcessors = new ArrayList();
///这个List用于存放Bean工厂处理器（BeanFactoryPostProcessor）
        this.active = new AtomicBoolean();
//当前context是否正处于的活动状态
        this.closed = new AtomicBoolean();
//当前context是否关闭
        this.startupShutdownMonitor = new Object();
        this.applicationListeners = new LinkedHashSet();
        this.resourcePatternResolver = this.getResourcePatternResolver();
//从 PathMatchingResourcePatternResolver 类上的注释可知 该类支持 Ant 风格的路径解析
    }

设置配置文件路径

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) {
//遍历路径数组，将 解析(分解) 后的路径放到 configLocations 中
                this.configLocations[i] = this.resolvePath(locations[i]).trim();
            }
        } else {
            this.configLocations = null;
        }

    }

调用refresh方法

AbstractApplicationContext的refresh()方法是spring的核心，在其中完成了容器的初始化

 public void refresh() throws BeansException, IllegalStateException {
        synchronized(this.startupShutdownMonitor) {
            this.prepareRefresh();
            ConfigurableListableBeanFactory beanFactory = this.obtainFreshBeanFactory();
            this.prepareBeanFactory(beanFactory);

            try {
                this.postProcessBeanFactory(beanFactory);
                this.invokeBeanFactoryPostProcessors(beanFactory);
                this.registerBeanPostProcessors(beanFactory);
//实例化和注册beanFactory中扩展了BeanPostProcessor的bean。
                this.initMessageSource();
                this.initApplicationEventMulticaster();
                this.onRefresh();
                this.registerListeners();
                this.finishBeanFactoryInitialization(beanFactory);
                this.finishRefresh();
            } catch (BeansException var9) {
                if (this.logger.isWarnEnabled()) {
                    this.logger.warn("Exception encountered during context initialization - cancelling refresh attempt: " + var9);
                }

                this.destroyBeans();
                this.cancelRefresh(var9);
                throw var9;
            } finally {
                this.resetCommonCaches();
            }

        }
    }

//这里得新写一篇

//以上就是实例化ApplicationContext的过程