spring 容器的建立對應 SpringApplication 中 run 中呼叫的 createApplicationContext 方法。這裡建立了一個 web 容器，接下就進去 prepareContext 容器準備階段：

  private void prepareContext(ConfigurableApplicationContext context,ConfigurableEnvironment environment,SpringApplicationRunListeners listeners,ApplicationArguments applicationArguments,Banner printedBanner) {
    //為容器設定環境
    context.setEnvironment(environment);
    //這裡的空實現留給開發者擴充套件，設定資料轉換的ConversionService
    postProcessApplicationContext(context);
    //執行容器中的 Initializers 的 initialize 方法
    applyInitializers(context);
    listeners.contextPrepared(context);
    if (this.logStartupInfo) {
      logStartupInfo(context.getParent() == null);
      logStartupProfileInfo(context);
    }
    // Add boot specific singleton beans
    ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
    beanFactory.registerSingleton("springApplicationArguments",applicationArguments);
    if (printedBanner != null) {
      beanFactory.registerSingleton("springBootBanner",printedBanner);
    }
    if (beanFactory instanceof DefaultListableBeanFactory) {
      ((DefaultListableBeanFactory) beanFactory)
          .setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
    }
    if (this.lazyInitialization) {
      context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());
    }
    // Load the sources
    Set<Object> sources = getAllSources();
    Assert.notEmpty(sources,"Sources must not be empty");
    load(context,sources.toArray(new Object[0]));
    listeners.contextLoaded(context);
  }

看一下這裡的 load 方法,這裡主要把我們的啟動類作為 Bean 註冊到了 Spring 的容器中。

  protected void load(ApplicationContext context,Object[] sources) {
    if (logger.isDebugEnabled()) {
      logger.debug("Loading source " + StringUtils.arrayToCommaDelimitedString(sources));
    }
    BeanDefinitionLoader loader = createBeanDefinitionLoader(getBeanDefinitionRegistry(context),sources);
    if (this.beanNameGenerator != null) {
      loader.setBeanNameGenerator(this.beanNameGenerator);
    }
    if (this.resourceLoader != null) {
      loader.setResourceLoader(this.resourceLoader);
    }
    if (this.environment != null) {
      loader.setEnvironment(this.environment);
    }
    loader.load();
  }

  /**
   * Load the sources into the reader.
   * @return the number of loaded beans
   */
  int load() {
    int count = 0;
    for (Object source : this.sources) {
      count += load(source);
    }
    return count;
  }

  private int load(Object source) {
    Assert.notNull(source,"Source must not be null");
    if (source instanceof Class<?>) {
      return load((Class<?>) source);
    }
    if (source instanceof Resource) {
      return load((Resource) source);
    }
    if (source instanceof Package) {
      return load((Package) source);
    }
    if (source instanceof CharSequence) {
      return load((CharSequence) source);
    }
    throw new IllegalArgumentException("Invalid source type " + source.getClass());
  }

  private int load(Class<?> source) {
    if (isGroovyPresent() && GroovyBeanDefinitionSource.class.isAssignableFrom(source)) {
      // Any GroovyLoaders added in beans{} DSL can contribute beans here
      GroovyBeanDefinitionSource loader = BeanUtils.instantiateClass(source,GroovyBeanDefinitionSource.class);
      load(loader);
    }
    if (isEligible(source)) {
      this.annotatedReader.register(source);
      return 1;
    }
    return 0;
  }

再來看下 contextLoaded 方法，這裡將上下文設定到監聽器中，同時也把監聽器新增到上下文中。最後釋出了一個 ApplicationPreparedEvent 事件。

  public void contextLoaded(ConfigurableApplicationContext context) {
    for (ApplicationListener<?> listener : this.application.getListeners()) {
      if (listener instanceof ApplicationContextAware) {
        ((ApplicationContextAware) listener).setApplicationContext(context);
      }
      context.addApplicationListener(listener);
    }
    this.initialMulticaster.multicastEvent(new ApplicationPreparedEvent(this.application,this.args,context));
  }

到此這篇關於SpringBoot 建立容器的實現的文章就介紹到這了,更多相關SpringBoot 建立容器內容請搜尋我們以前的文章或繼續瀏覽下面的相關文章希望大家以後多多支援我們！