public SpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
		this.resourceLoader = resourceLoader;
		Assert.notNull(primarySources, "PrimarySources must not be null");
		this.primarySources = new LinkedHashSet<>(Arrays.asList(primarySources));
		this.webApplicationType = WebApplicationType.deduceFromClasspath();
		this.bootstrapRegistryInitializers = new ArrayList<>(
				getSpringFactoriesInstances(BootstrapRegistryInitializer.class));
		setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
		this.mainApplicationClass = deduceMainApplicationClass();
	}

	private static Map<String, List<String>> loadSpringFactories(ClassLoader classLoader) {
		Map<String, List<String>> result = cache.get(classLoader);
		if (result != null) {
			return result;
		}

		result = new HashMap<>();
		try {
			Enumeration<URL> urls = classLoader.getResources(FACTORIES_RESOURCE_LOCATION);
			while (urls.hasMoreElements()) {
				URL url = urls.nextElement();
				UrlResource resource = new UrlResource(url);
				Properties properties = PropertiesLoaderUtils.loadProperties(resource);
				for (Map.Entry<?, ?> entry : properties.entrySet()) {
					String factoryTypeName = ((String) entry.getKey()).trim();
					String[] factoryImplementationNames =
							StringUtils.commaDelimitedListToStringArray((String) entry.getValue());
					for (String factoryImplementationName : factoryImplementationNames) {
						result.computeIfAbsent(factoryTypeName, key -> new ArrayList<>())
								.add(factoryImplementationName.trim());
					}
				}
			}

			// Replace all lists with unmodifiable lists containing unique elements
			result.replaceAll((factoryType, implementations) -> implementations.stream().distinct()
					.collect(Collectors.collectingAndThen(Collectors.toList(), Collections::unmodifiableList)));
			cache.put(classLoader, result);
		}
		catch (IOException ex) {
			throw new IllegalArgumentException("Unable to load factories from location [" +
					FACTORIES_RESOURCE_LOCATION + "]", ex);
		}
		return result;
	}

long startTime = System.nanoTime();
DefaultBootstrapContext bootstrapContext = createBootstrapContext();
ConfigurableApplicationContext context = null;
configureHeadlessProperty();
SpringApplicationRunListeners listeners = getRunListeners(args);
listeners.starting(bootstrapContext, this.mainApplicationClass);

private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,
DefaultBootstrapContext bootstrapContext, ApplicationArguments applicationArguments) {
// Create and configure the environment
ConfigurableEnvironment environment = getOrCreateEnvironment();
configureEnvironment(environment, applicationArguments.getSourceArgs());
ConfigurationPropertySources.attach(environment);
listeners.environmentPrepared(bootstrapContext, environment);
DefaultPropertiesPropertySource.moveToEnd(environment);
Assert.state(!environment.containsProperty("spring.main.environment-prefix"),
"Environment prefix cannot be set via properties.");
bindToSpringApplication(environment);
if (!this.isCustomEnvironment) {
EnvironmentConverter environmentConverter = new EnvironmentConverter(getClassLoader());
environment = environmentConverter.convertEnvironmentIfNecessary(environment, deduceEnvironmentClass());
}
ConfigurationPropertySources.attach(environment);
return environment;
}

Banner printedBanner = printBanner(environment);
context = createApplicationContext();

	private void prepareContext(DefaultBootstrapContext bootstrapContext, ConfigurableApplicationContext context,
			ConfigurableEnvironment environment, SpringApplicationRunListeners listeners,
			ApplicationArguments applicationArguments, Banner printedBanner) {
		context.setEnvironment(environment);
		postProcessApplicationContext(context);
		applyInitializers(context);
		listeners.contextPrepared(context);
		bootstrapContext.close(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 AbstractAutowireCapableBeanFactory) {
			((AbstractAutowireCapableBeanFactory) beanFactory).setAllowCircularReferences(this.allowCircularReferences);
			if (beanFactory instanceof DefaultListableBeanFactory) {
				((DefaultListableBeanFactory) beanFactory)
					.setAllowBeanDefinitionOverriding(this.allowBeanDefinitionOverriding);
			}
		}
		if (this.lazyInitialization) {
			context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());
		}
		context.addBeanFactoryPostProcessor(new PropertySourceOrderingBeanFactoryPostProcessor(context));
		// 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);
	}

	void addRuntimeShutdownHook() {
try {
Runtime.getRuntime().addShutdownHook(new Thread(this, "SpringApplicationShutdownHook"));
}
catch (AccessControlException ex) {
// Not allowed in some environments
}
}
@Override
public void run() {
Set<ConfigurableApplicationContext> contexts;
Set<ConfigurableApplicationContext> closedContexts;
Set<Runnable> actions;
synchronized (SpringApplicationShutdownHook.class) {
this.inProgress = true;
contexts = new LinkedHashSet<>(this.contexts);
closedContexts = new LinkedHashSet<>(this.closedContexts);
actions = new LinkedHashSet<>(this.handlers.getActions());
}
contexts.forEach(this::closeAndWait);
closedContexts.forEach(this::closeAndWait);
actions.forEach(Runnable::run);
}

private void load(Object source) {
Assert.notNull(source, "Source must not be null");
if (source instanceof Class<?>) {
load((Class<?>) source);
return;
}
if (source instanceof Resource) {
load((Resource) source);
return;
}
if (source instanceof Package) {
load((Package) source);
return;
}
if (source instanceof CharSequence) {
load((CharSequence) source);
return;
}
throw new IllegalArgumentException("Invalid source type " + source.getClass());
}

private void 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);
((GroovyBeanDefinitionReader) this.groovyReader).beans(loader.getBeans());
}
if (isEligible(source)) {
this.annotatedReader.register(source);
}
}

private void load(Resource source) {
if (source.getFilename().endsWith(".groovy")) {
if (this.groovyReader == null) {
throw new BeanDefinitionStoreException("Cannot load Groovy beans without Groovy on classpath");
}
this.groovyReader.loadBeanDefinitions(source);
}
else {
if (this.xmlReader == null) {
throw new BeanDefinitionStoreException("Cannot load XML bean definitions when XML support is disabled");
}
this.xmlReader.loadBeanDefinitions(source);
}
}

private void load(Package source) {
this.scanner.scan(source.getName());
}

private void load(CharSequence source) {
String resolvedSource = this.scanner.getEnvironment().resolvePlaceholders(source.toString());
// Attempt as a Class
try {
load(ClassUtils.forName(resolvedSource, null));
return;
}
catch (IllegalArgumentException | ClassNotFoundException ex) {
// swallow exception and continue
}
// Attempt as Resources
if (loadAsResources(resolvedSource)) {
return;
}
// Attempt as package
Package packageResource = findPackage(resolvedSource);
if (packageResource != null) {
load(packageResource);
return;
}
throw new IllegalArgumentException("Invalid source '" + resolvedSource + "'");
}