Spring Boot2.0版本源码(六)：Spring Boot的启动加载器

自定义启动加载器
实现ApplicationRunner接口，重写run()方法即可

SpringApplication.run()方法中有一个callRunners(context, applicationArguments);就是在springboot运行时调用启动加载器的地方

/**
	 * Run the Spring application, creating and refreshing a new
	 * {@link ApplicationContext}.
	 * @param args the application arguments (usually passed from a Java main method)
	 * @return a running {@link ApplicationContext}
	 */
	public ConfigurableApplicationContext run(String... args) {
		StopWatch stopWatch = new StopWatch(); // 计时器
		stopWatch.start(); // 开启计时器
		ConfigurableApplicationContext context = null;
		Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
		configureHeadlessProperty();
		SpringApplicationRunListeners listeners = getRunListeners(args);
		// listener事件的触发
		listeners.starting();
		try {
			ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
			ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
			configureIgnoreBeanInfo(environment);
			// 打印banner
			Banner printedBanner = printBanner(environment);
			context = createApplicationContext();
			exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
					new Class[] { ConfigurableApplicationContext.class }, context);
			// 环境准备
			prepareContext(context, environment, listeners, applicationArguments, printedBanner);
			// bean的注入
			refreshContext(context);
			afterRefresh(context, applicationArguments);
			stopWatch.stop(); // 停止计时器
			if (this.logStartupInfo) {
				new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
			}
			listeners.started(context);
			// 启动加载的启动
			callRunners(context, applicationArguments);
		}
		catch (Throwable ex) {
			handleRunFailure(context, ex, exceptionReporters, listeners);
			throw new IllegalStateException(ex);
		}

callRunners(context, applicationArguments);源码如下

private void callRunners(ApplicationContext context, ApplicationArguments args) {
		List<Object> runners = new ArrayList<>();
		// ApplicationRunner是一种启动加载器
		runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
		// CommandLineRunner是另一种启动加载器
		runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
		// 排序
		AnnotationAwareOrderComparator.sort(runners);
		for (Object runner : new LinkedHashSet<>(runners)) {
			if (runner instanceof ApplicationRunner) {
				// 调用这些bean的sun方法
				callRunner((ApplicationRunner) runner, args);
			}
			if (runner instanceof CommandLineRunner) {
				callRunner((CommandLineRunner) runner, args);
			}
		}
	}