> For the complete documentation index, see [llms.txt](https://maxwell.gitbook.io/way-to-architect/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://maxwell.gitbook.io/way-to-architect/kuang-jia-huo-gong-ju/spring/springji-chu/beande-sheng-ming-zhou-qi/xmlge-shi-de-ying-yong-qi-dong-de-guo-cheng.md).

# Xml格式的应用启动2

第二步：obtainFreshBeanFactory()：获取BeanFactory

```java
protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
    refreshBeanFactory();
    ConfigurableListableBeanFactory beanFactory = getBeanFactory();
    if (logger.isDebugEnabled()) {
        logger.debug("Bean factory for " + getDisplayName() + ": " + beanFactory);
    }
    return beanFactory;
}
```

refreshBeanFactory()是留给子类实现的，注释说是加载配置信息，具体到ClassPathXmlApplicationContext，它的实现其实是在父类AbstractRefreshableApplicationContext中，代码如下：

```java
protected final void refreshBeanFactory() throws BeansException {
    if (hasBeanFactory()) {
        destroyBeans();
        closeBeanFactory();
    }
    try {
        DefaultListableBeanFactory beanFactory = createBeanFactory();
        beanFactory.setSerializationId(getId());
        customizeBeanFactory(beanFactory);
        loadBeanDefinitions(beanFactory);
        synchronized (this.beanFactoryMonitor) {
            this.beanFactory = beanFactory;
        }
    }
    catch (IOException ex) {
        throw new ApplicationContextException("I/O error parsing bean definition source for " + getDisplayName(), ex);
    }
}
```

AbstractRefreshableApplicationContext中持有一个DefaultListableBeanFactory实例beanFactory，hasBeanFactory其实是看beanFactory是否为空，如果不为空，说明之前实例化过，则进销毁之前的bean管理的Bean并关闭该beanFactory：

```java
protected void destroyBeans() {
    getBeanFactory().destroySingletons();
}
```

这里的destroySingletons()其实就是从单例注册中心（理解为map\<beanName, bean>）clearAll。即destroy并不是从JVM将之前创建的Bean销毁（其实也没有这样的方法可以达到这样的效果），只是将其从该Context脱离出来。

closeBeanFactory则是将该Context持有的DefaultListableBeanFactory实例beanFactory置为null。

现在，看createBeanFactory，由于没有父工厂，其实就是new了一个DefaultListableBeanFactory实例。

```java
protected DefaultListableBeanFactory createBeanFactory() {
    return new DefaultListableBeanFactory(getInternalParentBeanFactory());
}
```

customizeBeanFactory是进行定制化Bean工厂：

```java
protected void customizeBeanFactory(DefaultListableBeanFactory beanFactory) {
    if (this.allowBeanDefinitionOverriding != null) {
        beanFactory.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
    }
    if (this.allowCircularReferences != null) {
        beanFactory.setAllowCircularReferences(this.allowCircularReferences);
    }
}
```

�由于AbstractRefreshableApplicationContext中这两个变量初始值均为null，而最终的实现类ClassPathXmlApplicationContext也没有设置这两个值，所以这两个值均为null，则该Context中的DefaultListableBeanFactory采用默认值true，即允许覆盖之前的BeanDefinition（即添加\<beanName->BeanDefinition>时，发现已经存在相同BeanName的\<beanName->BeanDefinition>，则替换掉原来的），允许循环依赖。

loadBeanDefinitions则是去真正加载BeanDefinition，具体实现是在AbstractXmlApplicationContext中，由XmlBeanDefinitionReader去完成。这里流程比较复杂，暂时跳过。需要清楚的一点是，该方法是将完整的BeanDefinitions加载进BeanFactory。

这一步的主要工作：

①创建(new)一个DefaultListableBeanFactory实例（如果之前存在，则销毁重新new），设置为允许覆盖BeanDefinition，并允许循环依赖。

②使用XmlBeanDefinitionReader加载BeanDefinitions到DefaultListableBeanFactory。

�


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://maxwell.gitbook.io/way-to-architect/kuang-jia-huo-gong-ju/spring/springji-chu/beande-sheng-ming-zhou-qi/xmlge-shi-de-ying-yong-qi-dong-de-guo-cheng.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.