spring 容器的创立对应 SpringApplication 中 run 中调用的 createApplicationContext 办法。这里创立了一个 web 容器，接下就进去 prepareContext 容器筹备阶段：
private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,
SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) {
// 为容器设置环境
context.setEnvironment(environment);
// 这里的空实现留给开发者扩大，设置数据转换的 ConversionService
postProcessApplicationContext(context);
// 执行容器中的 Initializers 的 initialize 办法
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);
}看一下这里的 load 办法, 这里次要把咱们的启动类作为 Bean 注册到了 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;
}再来看下 contextLoaded 办法，这里将上下文设置到监听器中，同时也把监听器增加到上下文中。最初公布了一个 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));
}