Refresh

简介

ConfigurableApplicationContext 定义了容器加载或刷新的接口 refresh。

Load or refresh the persistent representation of the configuration, which might be from Java-based configuration, an XML file, a properties file, a relational database schema, or some other format.

As this is a startup method, it should destroy already created singletons if it fails, to avoid dangling resources. In other words, after invocation of this method, either all or no singletons at all should be instantiated.

定义

package org.springframework.context;

public interface ConfigurableApplicationContext extends ApplicationContext, Lifecycle, Closeable {

    void refresh() throws BeansException, IllegalStateException;

}

Refresh

package org.springframework.context.support;

public abstract class AbstractApplicationContext extends DefaultResourceLoader
    implements ConfigurableApplicationContext {

    @Override
    public void refresh() throws BeansException, IllegalStateException {
        synchronized (this.startupShutdownMonitor) {
            // Prepare this context for refreshing.
            prepareRefresh();

            // Tell the subclass to refresh the internal bean factory.
            ConfigurableListableBeanFactory beanFactory = obtainFreshBeanFactory();

            // Prepare the bean factory for use in this context.
            prepareBeanFactory(beanFactory);

            try {
                // Allows post-processing of the bean factory in context subclasses.
                postProcessBeanFactory(beanFactory);

                // Invoke factory processors registered as beans in the context.
                invokeBeanFactoryPostProcessors(beanFactory);

                // Register bean processors that intercept bean creation.
                registerBeanPostProcessors(beanFactory);

                // Initialize message source for this context.
                initMessageSource();

                // Initialize event multicaster for this context.
                initApplicationEventMulticaster();

                // Initialize other special beans in specific context subclasses.
                onRefresh();

                // Check for listener beans and register them.
                registerListeners();

                // Instantiate all remaining (non-lazy-init) singletons.
                // 实例化所有非懒加载的单例
                finishBeanFactoryInitialization(beanFactory);

                // Last step: publish corresponding event.
                finishRefresh();
            } catch (BeansException ex) {
                if (logger.isWarnEnabled()) {
                    logger.warn("Exception encountered during context initialization - " +
                        "cancelling refresh attempt: " + ex);
                }

                // Destroy already created singletons to avoid dangling resources.
                destroyBeans();

                // Reset 'active' flag.
                cancelRefresh(ex);

                // Propagate exception to caller.
                throw ex;
            } finally {
                // Reset common introspection caches in Spring's core, since we
                // might not ever need metadata for singleton beans anymore...
                resetCommonCaches();
            }
        }
    }

}

refresh