BaseCommandController extends AbstractController extends WebContentGenerator WebContentGenerator extends WebApplicationObjectSupport extends ApplicationObjectSupport implements ApplicationContextAware
/**
* Subclasses can override this for custom initialization behavior.
* Gets called by <code>setApplicationContext</code> after setting the context instance.
* <p>Note: Does </i>not</i> get called on reinitialization of the context
* but rather just on first initialization of this object's context reference.
* @throws ApplicationContextException in case of initialization errors
* @throws BeansException if thrown by ApplicationContext methods
* @see #setApplicationContext
*/
protected void initApplicationContext() throws BeansException {
}
愿意為子類可以把初始化bean 動作放入此方法，可以自定義一些動作。
我們再來看看調用
public final void setApplicationContext(ApplicationContext context) throws BeansException {
if (context == null && !isContextRequired()) {
// Reset internal context state.
this.applicationContext = null;
this.messageSourceAccessor = null;
}
else if (this.applicationContext == null) {
// Initialize with passed-in context.
if (!requiredContextClass().isInstance(context)) {
throw new ApplicationContextException(
"Invalid application context: needs to be of type [" + requiredContextClass().getName() + "]");
}
this.applicationContext = context;
this.messageSourceAccessor = new MessageSourceAccessor(context);
initApplicationContext();
}
else {
// Ignore reinitialization if same context passed in.
if (this.applicationContext != context) {
throw new ApplicationContextException(
"Cannot reinitialize with different application context: current one is [" +
this.applicationContext + "], passed-in one is [" + context + "]");
}
}
}
可以看到由 ApplicationObjectSupport 的 setApplicationContext 方法調用
而此方法為 ApplicationContextAware 的唯一接口方法，
public interface ApplicationContextAware {
/**
* Set the ApplicationContext that this object runs in.
* Normally this call will be used to initialize the object.
* <p>Invoked after population of normal bean properties but before an init callback such
* as {@link org.springframework.beans.factory.InitializingBean#afterPropertiesSet()}
* or a custom init-method. Invoked after {@link ResourceLoaderAware#setResourceLoader},
* {@link ApplicationEventPublisherAware#setApplicationEventPublisher} and
* {@link MessageSourceAware}, if applicable.
* @param applicationContext the ApplicationContext object to be used by this object
* @throws ApplicationContextException in case of context initialization errors
* @throws BeansException if thrown by application context methods
* @see org.springframework.beans.factory.BeanInitializationException
*/
void setApplicationContext(ApplicationContext applicationContext) throws BeansException;
}
此方法被 ApplicationContextAwareProcessor 的 postProcessBeforeInitialization 調用
ApplicationContextAwareProcessor implements BeanPostProcessor
public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
if (bean instanceof ResourceLoaderAware) {
((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);
}
if (bean instanceof ApplicationEventPublisherAware) {
((ApplicationEventPublisherAware) bean).setApplicationEventPublisher(this.applicationContext);
}
if (bean instanceof MessageSourceAware) {
((MessageSourceAware) bean).setMessageSource(this.applicationContext);
}
if (bean instanceof ApplicationContextAware) {
((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
}
return bean;
}