public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
...
// 通过 SpringFactories 方式获取 ApplicationContextInitializer
// 允许在 ApplicationContext refresh 之前,对其实例做进一步的设置和处理
setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
// 通过 SpringFactories 方式获取 ApplicationListener 的实现,接收事件
setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
// 获取启动的类
this.mainApplicationClass = deduceMainApplicationClass();
}
private Class<?> deduceMainApplicationClass() {
...
StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
for (StackTraceElement stackTraceElement : stackTrace) {
// 遍历调用栈,获取第一个 main 方法
if ("main".equals(stackTraceElement.getMethodName())) {
return Class.forName(stackTraceElement.getClassName());
}
}
...
}
public ConfigurableApplicationContext run(String... args) {
...
// SpringFactories 方式获取 SpringApplicationRunListener
// ❤❤❤ 实现必须包含构造函数 public Xxx(SpringApplication application, String[] args)
SpringApplicationRunListeners listeners = getRunListeners(args);
// 调用 SpringApplicationRunListener 的 starting 方法
// EventPublishingRunListener 发布 ApplicationStartingEvent 事件
listeners.starting();
try {
ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
// 调用 SpringApplicationRunListener 的 environmentPrepared 方法
// EventPublishingRunListener 发布 ApplicationEnvironmentPreparedEvent 事件
ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
configureIgnoreBeanInfo(environment);
//
Banner printedBanner = printBanner(environment);
context = createApplicationContext();
exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class, new Class[] { ConfigurableApplicationContext.class }, context);
// ❤❤❤ 调用 ApplicationContextInitializer#initialize(context)
//
// 调用 SpringApplicationRunListener 的 contextPrepared 方法
// EventPublishingRunListener 发布 ApplicationContextInitializedEvent 事件
//
// 调用 SpringApplicationRunListener 的 contextLoaded 方法
// EventPublishingRunListener 发布 ApplicationPreparedEvent 事件
prepareContext(context, environment, listeners, applicationArguments, printedBanner);
refreshContext(context);
afterRefresh(context, applicationArguments);
...
// 调用 SpringApplicationRunListener 的 started 方法
// EventPublishingRunListener 发布 ApplicationStartedEvent 事件
listeners.started(context);
// ❤❤❤ 从 context 中获取 ApplicationRunner 和 CommandLineRunner,并调用 ❤❤❤
callRunners(context, applicationArguments);
}
catch (Throwable ex) {
// 调用 SpringApplicationRunListener 的 failed 方法
// EventPublishingRunListener 发布 ApplicationFailedEvent 事件
handleRunFailure(context, ex, exceptionReporters, listeners);
throw new IllegalStateException(ex);
}
try {
// 调用 SpringApplicationRunListener 的 running 方法
// EventPublishingRunListener 发布 ApplicationReadyEvent 事件
listeners.running(context);
}
catch (Throwable ex) {
// 调用 SpringApplicationRunListener 的 failed 方法
// EventPublishingRunListener 发布 ApplicationFailedEvent 事件
handleRunFailure(context, ex, exceptionReporters, null);
throw new IllegalStateException(ex);
}
return context;
}
package org.springframework.boot.web.servlet.support;
...
public abstract class SpringBootServletInitializer implements WebApplicationInitializer {
...
@Override
public void onStartup(ServletContext servletContext) throws ServletException {
...
WebApplicationContext rootAppContext = createRootApplicationContext(servletContext);
...
}
protected WebApplicationContext createRootApplicationContext(ServletContext servletContext) {
// SpringApplication 构建器,设置默认配置
SpringApplicationBuilder builder = createSpringApplicationBuilder();
builder.main(getClass());
...
builder.initializers(new ServletContextApplicationContextInitializer(servletContext));
builder.contextClass(AnnotationConfigServletWebServerApplicationContext.class);
// ❤❤❤ 自定义扩展配置
builder = configure(builder);
builder.listeners(new WebEnvironmentPropertySourceInitializer(servletContext));
SpringApplication application = builder.build();
...
// Ensure error pages are registered
...
// 调用 SpringApplication#run
return run(application);
}
...
}