Spring中refresh分析之obtainFreshBeanFactory方法详解

关联博文：

AbstractApplicationContext中refresh方法详解

Spring中refresh分析之prepareRefresh方法详解

Spring中refresh分析之obtainFreshBeanFactory方法详解

Spring中refresh分析之prepareBeanFactory方法详解

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Spring中refresh分析之postProcessBeanFactory方法详解

Spring中refresh分析之invokeBeanFactoryPostProcessors方法详解

Spring中refresh分析之registerBeanPostProcessors方法详解

Spring中refresh分析之initMessageSource方法详解

Spring中refresh分析之initApplicationEventMulticaster方法详解

Spring中refresh分析之onRefresh方法详解

Spring中refresh分析之registerListeners方法详解

Spring中refresh分析之finishBeanFactoryInitialization方法详解

Spring中refresh分析之finishRefresh方法详解

接上文AbstractApplicationContext中refresh方法详解我们分析过prepareRefresh后，本文分析obtainFreshBeanFactory方法。

该方法主要是获取到应用上下文维护的beanFactory，默认是DefaultListableBeanFactory 。

ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();
// AbstractApplicationContext
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
  refreshBeanFactory();
  return getBeanFactory();
}

① refreshBeanFactory

GenericApplicationContext的refreshBeanFactory方法。其首先应用CAS思想设置刷新标志，然后为beanFactory设置序列化ID-默认是application。

@Override
protected final void refreshBeanFactory() throws IllegalStateException {
  if (!this.refreshed.compareAndSet(false, true)) {
    throw new IllegalStateException(
        "GenericApplicationContext does not support multiple refresh attempts: just call 'refresh' once");
  }
  this.beanFactory.setSerializationId(getId());
}

当前对象this指的是AnnotationConfigServletWebServerApplicationContext，而refreshBeanFactory调用是其传递祖父类GenericApplicationContext 。GenericApplicationContext 内部如下所示维护了beanFactory。

public class GenericApplicationContext extends AbstractApplicationContext implements BeanDefinitionRegistry {
  private final DefaultListableBeanFactory beanFactory;
  @Nullable
  private ResourceLoader resourceLoader;
  private boolean customClassLoader = false;
  private final AtomicBoolean refreshed = new AtomicBoolean();
  public GenericApplicationContext() {
    this.beanFactory = new DefaultListableBeanFactory();
  }
  //...
} 

② getBeanFactory

这里调用的仍旧是GenericApplicationContext的方法，如下所示，只是返回了内部维护的beanFactory，默认是DefaultListableBeanFactory。

@Override
public final ConfigurableListableBeanFactory getBeanFactory() {
  return this.beanFactory;
}

GenericApplicationContext关于BeanDefinition的行为比如get、remove，其实就是交给了beanFactory来处理。