/*
 * Copyright 2012-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.boot;

import java.lang.reflect.Constructor;
import java.security.AccessControlException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.CachedIntrospectionResults;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
import org.springframework.boot.Banner.Mode;
import org.springframework.boot.context.properties.bind.Bindable;
import org.springframework.boot.context.properties.bind.Binder;
import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
import org.springframework.boot.convert.ApplicationConversionService;
import org.springframework.boot.web.reactive.context.StandardReactiveWebEnvironment;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextInitializer;
import org.springframework.context.ApplicationListener;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.AnnotatedBeanDefinitionReader;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.AnnotationConfigUtils;
import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.GenericApplicationContext;
import org.springframework.core.GenericTypeResolver;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.ConfigurableConversionService;
import org.springframework.core.env.CommandLinePropertySource;
import org.springframework.core.env.CompositePropertySource;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;
import org.springframework.core.env.MapPropertySource;
import org.springframework.core.env.MutablePropertySources;
import org.springframework.core.env.PropertySource;
import org.springframework.core.env.SimpleCommandLinePropertySource;
import org.springframework.core.env.StandardEnvironment;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.ResourceLoader;
import org.springframework.core.io.support.SpringFactoriesLoader;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.CollectionUtils;
import org.springframework.util.ObjectUtils;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.StopWatch;
import org.springframework.util.StringUtils;
import org.springframework.web.context.support.StandardServletEnvironment;

Class that can be used to bootstrap and launch a Spring application from a Java main
method. By default class will perform the following steps to bootstrap your
application:

Create an appropriate ApplicationContext instance (depending on your classpath)
Register a CommandLinePropertySource to expose command line arguments as Spring properties
Refresh the application context, loading all singleton beans
Trigger any CommandLineRunner beans
 In most circumstances the static run(Class<?>, String[]) method can be called directly from your main method to bootstrap your application: 
@Configuration
@EnableAutoConfiguration
public class MyApplication  {
  // ... Bean definitions
  public static void main(String[] args) {
    SpringApplication.run(MyApplication.class, args);
  }
}

 For more advanced configuration a SpringApplication instance can be created and customized before being run: 
public static void main(String[] args) {
  SpringApplication application = new SpringApplication(MyApplication.class);
  // ... customize application settings here
  application.run(args)
}
 SpringApplications can read beans from a variety of different sources. It is generally recommended that a single @Configuration class is used to bootstrap your application, however, you may also set sources from: 

The fully qualified class name to be loaded by AnnotatedBeanDefinitionReader
The location of an XML resource to be loaded by XmlBeanDefinitionReader, or a groovy script to be loaded by GroovyBeanDefinitionReader
The name of a package to be scanned by ClassPathBeanDefinitionScanner
 Configuration properties are also bound to the SpringApplication. This makes it possible to set SpringApplication properties dynamically, like additional sources ("spring.main.sources" - a CSV list) the flag to indicate a web environment ("spring.main.web-application-type=none") or the flag to switch off the banner ("spring.main.banner-mode=off"). 
Author:
Phillip Webb, Dave Syer, Andy Wilkinson, Christian Dupuis, Stephane Nicoll, Jeremy Rickard, Craig Burke, Michael Simons, Madhura Bhave, Brian Clozel, Ethan Rubinson
See Also:
run(Class<?>, String[])
run(Class<?>[], String[])
SpringApplication(Class<?>...)
Since:
1.0.0/**
 * Class that can be used to bootstrap and launch a Spring application from a Java main
 * method. By default class will perform the following steps to bootstrap your
 * application:
 *
 * <ul>
 * <li>Create an appropriate {@link ApplicationContext} instance (depending on your
 * classpath)</li>
 * <li>Register a {@link CommandLinePropertySource} to expose command line arguments as
 * Spring properties</li>
 * <li>Refresh the application context, loading all singleton beans</li>
 * <li>Trigger any {@link CommandLineRunner} beans</li>
 * </ul>
 *
 * In most circumstances the static {@link #run(Class, String[])} method can be called
 * directly from your {@literal main} method to bootstrap your application:
 *
 * <pre class="code">
 * &#064;Configuration
 * &#064;EnableAutoConfiguration
 * public class MyApplication  {
 *
 *   // ... Bean definitions
 *
 *   public static void main(String[] args) {
 *     SpringApplication.run(MyApplication.class, args);
 *   }
 * }
 * </pre>
 *
 * <p>
 * For more advanced configuration a {@link SpringApplication} instance can be created and
 * customized before being run:
 *
 * <pre class="code">
 * public static void main(String[] args) {
 *   SpringApplication application = new SpringApplication(MyApplication.class);
 *   // ... customize application settings here
 *   application.run(args)
 * }
 * </pre>
 *
 * {@link SpringApplication}s can read beans from a variety of different sources. It is
 * generally recommended that a single {@code @Configuration} class is used to bootstrap
 * your application, however, you may also set {@link #getSources() sources} from:
 * <ul>
 * <li>The fully qualified class name to be loaded by
 * {@link AnnotatedBeanDefinitionReader}</li>
 * <li>The location of an XML resource to be loaded by {@link XmlBeanDefinitionReader}, or
 * a groovy script to be loaded by {@link GroovyBeanDefinitionReader}</li>
 * <li>The name of a package to be scanned by {@link ClassPathBeanDefinitionScanner}</li>
 * </ul>
 *
 * Configuration properties are also bound to the {@link SpringApplication}. This makes it
 * possible to set {@link SpringApplication} properties dynamically, like additional
 * sources ("spring.main.sources" - a CSV list) the flag to indicate a web environment
 * ("spring.main.web-application-type=none") or the flag to switch off the banner
 * ("spring.main.banner-mode=off").
 *
 * @author Phillip Webb
 * @author Dave Syer
 * @author Andy Wilkinson
 * @author Christian Dupuis
 * @author Stephane Nicoll
 * @author Jeremy Rickard
 * @author Craig Burke
 * @author Michael Simons
 * @author Madhura Bhave
 * @author Brian Clozel
 * @author Ethan Rubinson
 * @since 1.0.0
 * @see #run(Class, String[])
 * @see #run(Class[], String[])
 * @see #SpringApplication(Class...)
 */
public class SpringApplication {

	
The class name of application context that will be used by default for non-web
environments.
/**
	 * The class name of application context that will be used by default for non-web
	 * environments.
	 */
	public static final String DEFAULT_CONTEXT_CLASS = "org.springframework.context."
			+ "annotation.AnnotationConfigApplicationContext";

	
The class name of application context that will be used by default for web
environments.
/**
	 * The class name of application context that will be used by default for web
	 * environments.
	 */
	public static final String DEFAULT_SERVLET_WEB_CONTEXT_CLASS = "org.springframework.boot."
			+ "web.servlet.context.AnnotationConfigServletWebServerApplicationContext";

	
The class name of application context that will be used by default for reactive web
environments.
/**
	 * The class name of application context that will be used by default for reactive web
	 * environments.
	 */
	public static final String DEFAULT_REACTIVE_WEB_CONTEXT_CLASS = "org.springframework."
			+ "boot.web.reactive.context.AnnotationConfigReactiveWebServerApplicationContext";

	
Default banner location.
/**
	 * Default banner location.
	 */
	public static final String BANNER_LOCATION_PROPERTY_VALUE = SpringApplicationBannerPrinter.DEFAULT_BANNER_LOCATION;

	
Banner location property key.
/**
	 * Banner location property key.
	 */
	public static final String BANNER_LOCATION_PROPERTY = SpringApplicationBannerPrinter.BANNER_LOCATION_PROPERTY;

	private static final String SYSTEM_PROPERTY_JAVA_AWT_HEADLESS = "java.awt.headless";

	private static final Log logger = LogFactory.getLog(SpringApplication.class);

	private Set<Class<?>> primarySources;

	private Set<String> sources = new LinkedHashSet<>();

	private Class<?> mainApplicationClass;

	private Banner.Mode bannerMode = Banner.Mode.CONSOLE;

	private boolean logStartupInfo = true;

	private boolean addCommandLineProperties = true;

	private boolean addConversionService = true;

	private Banner banner;

	private ResourceLoader resourceLoader;

	private BeanNameGenerator beanNameGenerator;

	private ConfigurableEnvironment environment;

	private Class<? extends ConfigurableApplicationContext> applicationContextClass;

	private WebApplicationType webApplicationType;

	private boolean headless = true;

	private boolean registerShutdownHook = true;

	private List<ApplicationContextInitializer<?>> initializers;

	private List<ApplicationListener<?>> listeners;

	private Map<String, Object> defaultProperties;

	private Set<String> additionalProfiles = new HashSet<>();

	private boolean allowBeanDefinitionOverriding;

	private boolean isCustomEnvironment = false;

	private boolean lazyInitialization = false;

	
Create a new SpringApplication instance. The application context will load beans from the specified primary sources (see class-level documentation for details. The instance can be customized before calling run(String...). 
Params:
primarySources – the primary bean sources
See Also:
run(Class<?>, String[])
SpringApplication(ResourceLoader, Class<?>...)
setSources(Set<String>)/**
	 * Create a new {@link SpringApplication} instance. The application context will load
	 * beans from the specified primary sources (see {@link SpringApplication class-level}
	 * documentation for details. The instance can be customized before calling
	 * {@link #run(String...)}.
	 * @param primarySources the primary bean sources
	 * @see #run(Class, String[])
	 * @see #SpringApplication(ResourceLoader, Class...)
	 * @see #setSources(Set)
	 */
	public SpringApplication(Class<?>... primarySources) {
		this(null, primarySources);
	}

	
Create a new SpringApplication instance. The application context will load beans from the specified primary sources (see class-level documentation for details. The instance can be customized before calling run(String...). 
Params:
resourceLoader – the resource loader to use
primarySources – the primary bean sources
See Also:
run(Class<?>, String[])
setSources(Set<String>)/**
	 * Create a new {@link SpringApplication} instance. The application context will load
	 * beans from the specified primary sources (see {@link SpringApplication class-level}
	 * documentation for details. The instance can be customized before calling
	 * {@link #run(String...)}.
	 * @param resourceLoader the resource loader to use
	 * @param primarySources the primary bean sources
	 * @see #run(Class, String[])
	 * @see #setSources(Set)
	 */
	@SuppressWarnings({ "unchecked", "rawtypes" })
	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();
		setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
		this.mainApplicationClass = deduceMainApplicationClass();
	}

	private Class<?> deduceMainApplicationClass() {
		try {
			StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
			for (StackTraceElement stackTraceElement : stackTrace) {
				if ("main".equals(stackTraceElement.getMethodName())) {
					return Class.forName(stackTraceElement.getClassName());
				}
			}
		}
		catch (ClassNotFoundException ex) {
			// Swallow and continue
		}
		return null;
	}

	
Run the Spring application, creating and refreshing a new ApplicationContext. 
Params:
args – the application arguments (usually passed from a Java main method)
Returns:
a running ApplicationContext/**
	 * 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();
		stopWatch.start();
		ConfigurableApplicationContext context = null;
		Collection<SpringBootExceptionReporter> exceptionReporters = new ArrayList<>();
		configureHeadlessProperty();
		SpringApplicationRunListeners listeners = getRunListeners(args);
		listeners.starting();
		try {
			ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
			ConfigurableEnvironment environment = prepareEnvironment(listeners, applicationArguments);
			configureIgnoreBeanInfo(environment);
			Banner printedBanner = printBanner(environment);
			context = createApplicationContext();
			exceptionReporters = getSpringFactoriesInstances(SpringBootExceptionReporter.class,
					new Class[] { ConfigurableApplicationContext.class }, context);
			prepareContext(context, environment, listeners, applicationArguments, printedBanner);
			refreshContext(context);
			afterRefresh(context, applicationArguments);
			stopWatch.stop();
			if (this.logStartupInfo) {
				new StartupInfoLogger(this.mainApplicationClass).logStarted(getApplicationLog(), stopWatch);
			}
			listeners.started(context);
			callRunners(context, applicationArguments);
		}
		catch (Throwable ex) {
			handleRunFailure(context, ex, exceptionReporters, listeners);
			throw new IllegalStateException(ex);
		}

		try {
			listeners.running(context);
		}
		catch (Throwable ex) {
			handleRunFailure(context, ex, exceptionReporters, null);
			throw new IllegalStateException(ex);
		}
		return context;
	}

	private ConfigurableEnvironment prepareEnvironment(SpringApplicationRunListeners listeners,
			ApplicationArguments applicationArguments) {
		// Create and configure the environment
		ConfigurableEnvironment environment = getOrCreateEnvironment();
		configureEnvironment(environment, applicationArguments.getSourceArgs());
		ConfigurationPropertySources.attach(environment);
		listeners.environmentPrepared(environment);
		bindToSpringApplication(environment);
		if (!this.isCustomEnvironment) {
			environment = new EnvironmentConverter(getClassLoader()).convertEnvironmentIfNecessary(environment,
					deduceEnvironmentClass());
		}
		ConfigurationPropertySources.attach(environment);
		return environment;
	}

	private Class<? extends StandardEnvironment> deduceEnvironmentClass() {
		switch (this.webApplicationType) {
		case SERVLET:
			return StandardServletEnvironment.class;
		case REACTIVE:
			return StandardReactiveWebEnvironment.class;
		default:
			return StandardEnvironment.class;
		}
	}

	private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,
			SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) {
		context.setEnvironment(environment);
		postProcessApplicationContext(context);
		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);
	}

	private void refreshContext(ConfigurableApplicationContext context) {
		refresh((ApplicationContext) context);
		if (this.registerShutdownHook) {
			try {
				context.registerShutdownHook();
			}
			catch (AccessControlException ex) {
				// Not allowed in some environments.
			}
		}
	}

	private void configureHeadlessProperty() {
		System.setProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS,
				System.getProperty(SYSTEM_PROPERTY_JAVA_AWT_HEADLESS, Boolean.toString(this.headless)));
	}

	private SpringApplicationRunListeners getRunListeners(String[] args) {
		Class<?>[] types = new Class<?>[] { SpringApplication.class, String[].class };
		return new SpringApplicationRunListeners(logger,
				getSpringFactoriesInstances(SpringApplicationRunListener.class, types, this, args));
	}

	private <T> Collection<T> getSpringFactoriesInstances(Class<T> type) {
		return getSpringFactoriesInstances(type, new Class<?>[] {});
	}

	private <T> Collection<T> getSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes, Object... args) {
		ClassLoader classLoader = getClassLoader();
		// Use names and ensure unique to protect against duplicates
		Set<String> names = new LinkedHashSet<>(SpringFactoriesLoader.loadFactoryNames(type, classLoader));
		List<T> instances = createSpringFactoriesInstances(type, parameterTypes, classLoader, args, names);
		AnnotationAwareOrderComparator.sort(instances);
		return instances;
	}

	@SuppressWarnings("unchecked")
	private <T> List<T> createSpringFactoriesInstances(Class<T> type, Class<?>[] parameterTypes,
			ClassLoader classLoader, Object[] args, Set<String> names) {
		List<T> instances = new ArrayList<>(names.size());
		for (String name : names) {
			try {
				Class<?> instanceClass = ClassUtils.forName(name, classLoader);
				Assert.isAssignable(type, instanceClass);
				Constructor<?> constructor = instanceClass.getDeclaredConstructor(parameterTypes);
				T instance = (T) BeanUtils.instantiateClass(constructor, args);
				instances.add(instance);
			}
			catch (Throwable ex) {
				throw new IllegalArgumentException("Cannot instantiate " + type + " : " + name, ex);
			}
		}
		return instances;
	}

	private ConfigurableEnvironment getOrCreateEnvironment() {
		if (this.environment != null) {
			return this.environment;
		}
		switch (this.webApplicationType) {
		case SERVLET:
			return new StandardServletEnvironment();
		case REACTIVE:
			return new StandardReactiveWebEnvironment();
		default:
			return new StandardEnvironment();
		}
	}

	
Template method delegating to configurePropertySources(ConfigurableEnvironment, String[]) and configureProfiles(ConfigurableEnvironment, String[]) in that order. Override this method for complete control over Environment customization, or one of the above for fine-grained control over property sources or profiles, respectively. 
Params:
environment – this application's environment
args – arguments passed to the run method
See Also:
configureProfiles(ConfigurableEnvironment, String[])
configurePropertySources(ConfigurableEnvironment, String[])/**
	 * Template method delegating to
	 * {@link #configurePropertySources(ConfigurableEnvironment, String[])} and
	 * {@link #configureProfiles(ConfigurableEnvironment, String[])} in that order.
	 * Override this method for complete control over Environment customization, or one of
	 * the above for fine-grained control over property sources or profiles, respectively.
	 * @param environment this application's environment
	 * @param args arguments passed to the {@code run} method
	 * @see #configureProfiles(ConfigurableEnvironment, String[])
	 * @see #configurePropertySources(ConfigurableEnvironment, String[])
	 */
	protected void configureEnvironment(ConfigurableEnvironment environment, String[] args) {
		if (this.addConversionService) {
			ConversionService conversionService = ApplicationConversionService.getSharedInstance();
			environment.setConversionService((ConfigurableConversionService) conversionService);
		}
		configurePropertySources(environment, args);
		configureProfiles(environment, args);
	}

	
Add, remove or re-order any PropertySources in this application's environment. 
Params:
environment – this application's environment
args – arguments passed to the run method
See Also:
configureEnvironment(ConfigurableEnvironment, String[])/**
	 * Add, remove or re-order any {@link PropertySource}s in this application's
	 * environment.
	 * @param environment this application's environment
	 * @param args arguments passed to the {@code run} method
	 * @see #configureEnvironment(ConfigurableEnvironment, String[])
	 */
	protected void configurePropertySources(ConfigurableEnvironment environment, String[] args) {
		MutablePropertySources sources = environment.getPropertySources();
		if (this.defaultProperties != null && !this.defaultProperties.isEmpty()) {
			sources.addLast(new MapPropertySource("defaultProperties", this.defaultProperties));
		}
		if (this.addCommandLineProperties && args.length > 0) {
			String name = CommandLinePropertySource.COMMAND_LINE_PROPERTY_SOURCE_NAME;
			if (sources.contains(name)) {
				PropertySource<?> source = sources.get(name);
				CompositePropertySource composite = new CompositePropertySource(name);
				composite.addPropertySource(
						new SimpleCommandLinePropertySource("springApplicationCommandLineArgs", args));
				composite.addPropertySource(source);
				sources.replace(name, composite);
			}
			else {
				sources.addFirst(new SimpleCommandLinePropertySource(args));
			}
		}
	}

	
Configure which profiles are active (or active by default) for this application environment. Additional profiles may be activated during configuration file processing via the spring.profiles.active property. 
Params:
environment – this application's environment
args – arguments passed to the run method
See Also:
configureEnvironment(ConfigurableEnvironment, String[])
ConfigFileApplicationListener/**
	 * Configure which profiles are active (or active by default) for this application
	 * environment. Additional profiles may be activated during configuration file
	 * processing via the {@code spring.profiles.active} property.
	 * @param environment this application's environment
	 * @param args arguments passed to the {@code run} method
	 * @see #configureEnvironment(ConfigurableEnvironment, String[])
	 * @see org.springframework.boot.context.config.ConfigFileApplicationListener
	 */
	protected void configureProfiles(ConfigurableEnvironment environment, String[] args) {
		Set<String> profiles = new LinkedHashSet<>(this.additionalProfiles);
		profiles.addAll(Arrays.asList(environment.getActiveProfiles()));
		environment.setActiveProfiles(StringUtils.toStringArray(profiles));
	}

	private void configureIgnoreBeanInfo(ConfigurableEnvironment environment) {
		if (System.getProperty(CachedIntrospectionResults.IGNORE_BEANINFO_PROPERTY_NAME) == null) {
			Boolean ignore = environment.getProperty("spring.beaninfo.ignore", Boolean.class, Boolean.TRUE);
			System.setProperty(CachedIntrospectionResults.IGNORE_BEANINFO_PROPERTY_NAME, ignore.toString());
		}
	}

	
Bind the environment to the SpringApplication. 
Params:
environment – the environment to bind/**
	 * Bind the environment to the {@link SpringApplication}.
	 * @param environment the environment to bind
	 */
	protected void bindToSpringApplication(ConfigurableEnvironment environment) {
		try {
			Binder.get(environment).bind("spring.main", Bindable.ofInstance(this));
		}
		catch (Exception ex) {
			throw new IllegalStateException("Cannot bind to SpringApplication", ex);
		}
	}

	private Banner printBanner(ConfigurableEnvironment environment) {
		if (this.bannerMode == Banner.Mode.OFF) {
			return null;
		}
		ResourceLoader resourceLoader = (this.resourceLoader != null) ? this.resourceLoader
				: new DefaultResourceLoader(null);
		SpringApplicationBannerPrinter bannerPrinter = new SpringApplicationBannerPrinter(resourceLoader, this.banner);
		if (this.bannerMode == Mode.LOG) {
			return bannerPrinter.print(environment, this.mainApplicationClass, logger);
		}
		return bannerPrinter.print(environment, this.mainApplicationClass, System.out);
	}

	
Strategy method used to create the ApplicationContext. By default this method will respect any explicitly set application context or application context class before falling back to a suitable default. 
See Also:
setApplicationContextClass(Class<? extends ConfigurableApplicationContext>)
Returns:
the application context (not yet refreshed)/**
	 * Strategy method used to create the {@link ApplicationContext}. By default this
	 * method will respect any explicitly set application context or application context
	 * class before falling back to a suitable default.
	 * @return the application context (not yet refreshed)
	 * @see #setApplicationContextClass(Class)
	 */
	protected ConfigurableApplicationContext createApplicationContext() {
		Class<?> contextClass = this.applicationContextClass;
		if (contextClass == null) {
			try {
				switch (this.webApplicationType) {
				case SERVLET:
					contextClass = Class.forName(DEFAULT_SERVLET_WEB_CONTEXT_CLASS);
					break;
				case REACTIVE:
					contextClass = Class.forName(DEFAULT_REACTIVE_WEB_CONTEXT_CLASS);
					break;
				default:
					contextClass = Class.forName(DEFAULT_CONTEXT_CLASS);
				}
			}
			catch (ClassNotFoundException ex) {
				throw new IllegalStateException(
						"Unable create a default ApplicationContext, please specify an ApplicationContextClass", ex);
			}
		}
		return (ConfigurableApplicationContext) BeanUtils.instantiateClass(contextClass);
	}

	
Apply any relevant post processing the ApplicationContext. Subclasses can apply additional processing as required. 
Params:
context – the application context/**
	 * Apply any relevant post processing the {@link ApplicationContext}. Subclasses can
	 * apply additional processing as required.
	 * @param context the application context
	 */
	protected void postProcessApplicationContext(ConfigurableApplicationContext context) {
		if (this.beanNameGenerator != null) {
			context.getBeanFactory().registerSingleton(AnnotationConfigUtils.CONFIGURATION_BEAN_NAME_GENERATOR,
					this.beanNameGenerator);
		}
		if (this.resourceLoader != null) {
			if (context instanceof GenericApplicationContext) {
				((GenericApplicationContext) context).setResourceLoader(this.resourceLoader);
			}
			if (context instanceof DefaultResourceLoader) {
				((DefaultResourceLoader) context).setClassLoader(this.resourceLoader.getClassLoader());
			}
		}
		if (this.addConversionService) {
			context.getBeanFactory().setConversionService(ApplicationConversionService.getSharedInstance());
		}
	}

	
Apply any ApplicationContextInitializers to the context before it is refreshed. 
Params:
context – the configured ApplicationContext (not refreshed yet)
See Also:
ConfigurableApplicationContext.refresh()/**
	 * Apply any {@link ApplicationContextInitializer}s to the context before it is
	 * refreshed.
	 * @param context the configured ApplicationContext (not refreshed yet)
	 * @see ConfigurableApplicationContext#refresh()
	 */
	@SuppressWarnings({ "rawtypes", "unchecked" })
	protected void applyInitializers(ConfigurableApplicationContext context) {
		for (ApplicationContextInitializer initializer : getInitializers()) {
			Class<?> requiredType = GenericTypeResolver.resolveTypeArgument(initializer.getClass(),
					ApplicationContextInitializer.class);
			Assert.isInstanceOf(requiredType, context, "Unable to call initializer.");
			initializer.initialize(context);
		}
	}

	
Called to log startup information, subclasses may override to add additional
logging.
Params:
isRoot – true if this application is the root of a context hierarchy/**
	 * Called to log startup information, subclasses may override to add additional
	 * logging.
	 * @param isRoot true if this application is the root of a context hierarchy
	 */
	protected void logStartupInfo(boolean isRoot) {
		if (isRoot) {
			new StartupInfoLogger(this.mainApplicationClass).logStarting(getApplicationLog());
		}
	}

	
Called to log active profile information.
Params:
context – the application context/**
	 * Called to log active profile information.
	 * @param context the application context
	 */
	protected void logStartupProfileInfo(ConfigurableApplicationContext context) {
		Log log = getApplicationLog();
		if (log.isInfoEnabled()) {
			String[] activeProfiles = context.getEnvironment().getActiveProfiles();
			if (ObjectUtils.isEmpty(activeProfiles)) {
				String[] defaultProfiles = context.getEnvironment().getDefaultProfiles();
				log.info("No active profile set, falling back to default profiles: "
						+ StringUtils.arrayToCommaDelimitedString(defaultProfiles));
			}
			else {
				log.info("The following profiles are active: "
						+ StringUtils.arrayToCommaDelimitedString(activeProfiles));
			}
		}
	}

	
Returns the Log for the application. By default will be deduced. 
Returns:
the application log/**
	 * Returns the {@link Log} for the application. By default will be deduced.
	 * @return the application log
	 */
	protected Log getApplicationLog() {
		if (this.mainApplicationClass == null) {
			return logger;
		}
		return LogFactory.getLog(this.mainApplicationClass);
	}

	
Load beans into the application context.
Params:
context – the context to load beans into
sources – the sources to load/**
	 * Load beans into the application context.
	 * @param context the context to load beans into
	 * @param sources the sources to load
	 */
	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();
	}

	
The ResourceLoader that will be used in the ApplicationContext.
Returns:
the resourceLoader the resource loader that will be used in the
ApplicationContext (or null if the default)/**
	 * The ResourceLoader that will be used in the ApplicationContext.
	 * @return the resourceLoader the resource loader that will be used in the
	 * ApplicationContext (or null if the default)
	 */
	public ResourceLoader getResourceLoader() {
		return this.resourceLoader;
	}

	
Either the ClassLoader that will be used in the ApplicationContext (if resourceLoader is set, or the context class loader (if not null), or the loader of the Spring ClassUtils class. 
Returns:
a ClassLoader (never null)/**
	 * Either the ClassLoader that will be used in the ApplicationContext (if
	 * {@link #setResourceLoader(ResourceLoader) resourceLoader} is set, or the context
	 * class loader (if not null), or the loader of the Spring {@link ClassUtils} class.
	 * @return a ClassLoader (never null)
	 */
	public ClassLoader getClassLoader() {
		if (this.resourceLoader != null) {
			return this.resourceLoader.getClassLoader();
		}
		return ClassUtils.getDefaultClassLoader();
	}

	
Get the bean definition registry.
Params:
context – the application context
Returns:
the BeanDefinitionRegistry if it can be determined/**
	 * Get the bean definition registry.
	 * @param context the application context
	 * @return the BeanDefinitionRegistry if it can be determined
	 */
	private BeanDefinitionRegistry getBeanDefinitionRegistry(ApplicationContext context) {
		if (context instanceof BeanDefinitionRegistry) {
			return (BeanDefinitionRegistry) context;
		}
		if (context instanceof AbstractApplicationContext) {
			return (BeanDefinitionRegistry) ((AbstractApplicationContext) context).getBeanFactory();
		}
		throw new IllegalStateException("Could not locate BeanDefinitionRegistry");
	}

	
Factory method used to create the BeanDefinitionLoader. 
Params:
registry – the bean definition registry
sources – the sources to load
Returns:
the BeanDefinitionLoader that will be used to load beans/**
	 * Factory method used to create the {@link BeanDefinitionLoader}.
	 * @param registry the bean definition registry
	 * @param sources the sources to load
	 * @return the {@link BeanDefinitionLoader} that will be used to load beans
	 */
	protected BeanDefinitionLoader createBeanDefinitionLoader(BeanDefinitionRegistry registry, Object[] sources) {
		return new BeanDefinitionLoader(registry, sources);
	}

	
Refresh the underlying ApplicationContext. 
Params:
applicationContext – the application context to refresh
Deprecated:
since 2.3.0 in favor of refresh(ConfigurableApplicationContext)/**
	 * Refresh the underlying {@link ApplicationContext}.
	 * @param applicationContext the application context to refresh
	 * @deprecated since 2.3.0 in favor of
	 * {@link #refresh(ConfigurableApplicationContext)}
	 */
	@Deprecated
	protected void refresh(ApplicationContext applicationContext) {
		Assert.isInstanceOf(ConfigurableApplicationContext.class, applicationContext);
		refresh((ConfigurableApplicationContext) applicationContext);
	}

	
Refresh the underlying ApplicationContext. 
Params:
applicationContext – the application context to refresh/**
	 * Refresh the underlying {@link ApplicationContext}.
	 * @param applicationContext the application context to refresh
	 */
	protected void refresh(ConfigurableApplicationContext applicationContext) {
		applicationContext.refresh();
	}

	
Called after the context has been refreshed.
Params:
context – the application context
args – the application arguments/**
	 * Called after the context has been refreshed.
	 * @param context the application context
	 * @param args the application arguments
	 */
	protected void afterRefresh(ConfigurableApplicationContext context, ApplicationArguments args) {
	}

	private void callRunners(ApplicationContext context, ApplicationArguments args) {
		List<Object> runners = new ArrayList<>();
		runners.addAll(context.getBeansOfType(ApplicationRunner.class).values());
		runners.addAll(context.getBeansOfType(CommandLineRunner.class).values());
		AnnotationAwareOrderComparator.sort(runners);
		for (Object runner : new LinkedHashSet<>(runners)) {
			if (runner instanceof ApplicationRunner) {
				callRunner((ApplicationRunner) runner, args);
			}
			if (runner instanceof CommandLineRunner) {
				callRunner((CommandLineRunner) runner, args);
			}
		}
	}

	private void callRunner(ApplicationRunner runner, ApplicationArguments args) {
		try {
			(runner).run(args);
		}
		catch (Exception ex) {
			throw new IllegalStateException("Failed to execute ApplicationRunner", ex);
		}
	}

	private void callRunner(CommandLineRunner runner, ApplicationArguments args) {
		try {
			(runner).run(args.getSourceArgs());
		}
		catch (Exception ex) {
			throw new IllegalStateException("Failed to execute CommandLineRunner", ex);
		}
	}

	private void handleRunFailure(ConfigurableApplicationContext context, Throwable exception,
			Collection<SpringBootExceptionReporter> exceptionReporters, SpringApplicationRunListeners listeners) {
		try {
			try {
				handleExitCode(context, exception);
				if (listeners != null) {
					listeners.failed(context, exception);
				}
			}
			finally {
				reportFailure(exceptionReporters, exception);
				if (context != null) {
					context.close();
				}
			}
		}
		catch (Exception ex) {
			logger.warn("Unable to close ApplicationContext", ex);
		}
		ReflectionUtils.rethrowRuntimeException(exception);
	}

	private void reportFailure(Collection<SpringBootExceptionReporter> exceptionReporters, Throwable failure) {
		try {
			for (SpringBootExceptionReporter reporter : exceptionReporters) {
				if (reporter.reportException(failure)) {
					registerLoggedException(failure);
					return;
				}
			}
		}
		catch (Throwable ex) {
			// Continue with normal handling of the original failure
		}
		if (logger.isErrorEnabled()) {
			logger.error("Application run failed", failure);
			registerLoggedException(failure);
		}
	}

	
Register that the given exception has been logged. By default, if the running in
the main thread, this method will suppress additional printing of the stacktrace.
Params:
exception – the exception that was logged/**
	 * Register that the given exception has been logged. By default, if the running in
	 * the main thread, this method will suppress additional printing of the stacktrace.
	 * @param exception the exception that was logged
	 */
	protected void registerLoggedException(Throwable exception) {
		SpringBootExceptionHandler handler = getSpringBootExceptionHandler();
		if (handler != null) {
			handler.registerLoggedException(exception);
		}
	}

	private void handleExitCode(ConfigurableApplicationContext context, Throwable exception) {
		int exitCode = getExitCodeFromException(context, exception);
		if (exitCode != 0) {
			if (context != null) {
				context.publishEvent(new ExitCodeEvent(context, exitCode));
			}
			SpringBootExceptionHandler handler = getSpringBootExceptionHandler();
			if (handler != null) {
				handler.registerExitCode(exitCode);
			}
		}
	}

	private int getExitCodeFromException(ConfigurableApplicationContext context, Throwable exception) {
		int exitCode = getExitCodeFromMappedException(context, exception);
		if (exitCode == 0) {
			exitCode = getExitCodeFromExitCodeGeneratorException(exception);
		}
		return exitCode;
	}

	private int getExitCodeFromMappedException(ConfigurableApplicationContext context, Throwable exception) {
		if (context == null || !context.isActive()) {
			return 0;
		}
		ExitCodeGenerators generators = new ExitCodeGenerators();
		Collection<ExitCodeExceptionMapper> beans = context.getBeansOfType(ExitCodeExceptionMapper.class).values();
		generators.addAll(exception, beans);
		return generators.getExitCode();
	}

	private int getExitCodeFromExitCodeGeneratorException(Throwable exception) {
		if (exception == null) {
			return 0;
		}
		if (exception instanceof ExitCodeGenerator) {
			return ((ExitCodeGenerator) exception).getExitCode();
		}
		return getExitCodeFromExitCodeGeneratorException(exception.getCause());
	}

	SpringBootExceptionHandler getSpringBootExceptionHandler() {
		if (isMainThread(Thread.currentThread())) {
			return SpringBootExceptionHandler.forCurrentThread();
		}
		return null;
	}

	private boolean isMainThread(Thread currentThread) {
		return ("main".equals(currentThread.getName()) || "restartedMain".equals(currentThread.getName()))
				&& "main".equals(currentThread.getThreadGroup().getName());
	}

	
Returns the main application class that has been deduced or explicitly configured.
Returns:
the main application class or null/**
	 * Returns the main application class that has been deduced or explicitly configured.
	 * @return the main application class or {@code null}
	 */
	public Class<?> getMainApplicationClass() {
		return this.mainApplicationClass;
	}

	
Set a specific main application class that will be used as a log source and to obtain version information. By default the main application class will be deduced. Can be set to null if there is no explicit application class. 
Params:
mainApplicationClass – the mainApplicationClass to set or null/**
	 * Set a specific main application class that will be used as a log source and to
	 * obtain version information. By default the main application class will be deduced.
	 * Can be set to {@code null} if there is no explicit application class.
	 * @param mainApplicationClass the mainApplicationClass to set or {@code null}
	 */
	public void setMainApplicationClass(Class<?> mainApplicationClass) {
		this.mainApplicationClass = mainApplicationClass;
	}

	
Returns the type of web application that is being run.
Returns:
the type of web application
Since:
2.0.0/**
	 * Returns the type of web application that is being run.
	 * @return the type of web application
	 * @since 2.0.0
	 */
	public WebApplicationType getWebApplicationType() {
		return this.webApplicationType;
	}

	
Sets the type of web application to be run. If not explicitly set the type of web
application will be deduced based on the classpath.
Params:
webApplicationType – the web application type
Since:
2.0.0/**
	 * Sets the type of web application to be run. If not explicitly set the type of web
	 * application will be deduced based on the classpath.
	 * @param webApplicationType the web application type
	 * @since 2.0.0
	 */
	public void setWebApplicationType(WebApplicationType webApplicationType) {
		Assert.notNull(webApplicationType, "WebApplicationType must not be null");
		this.webApplicationType = webApplicationType;
	}

	
Sets if bean definition overriding, by registering a definition with the same name as an existing definition, should be allowed. Defaults to false. 
Params:
allowBeanDefinitionOverriding – if overriding is allowed
See Also:
DefaultListableBeanFactory.setAllowBeanDefinitionOverriding(boolean)
Since:
2.1.0/**
	 * Sets if bean definition overriding, by registering a definition with the same name
	 * as an existing definition, should be allowed. Defaults to {@code false}.
	 * @param allowBeanDefinitionOverriding if overriding is allowed
	 * @since 2.1.0
	 * @see DefaultListableBeanFactory#setAllowBeanDefinitionOverriding(boolean)
	 */
	public void setAllowBeanDefinitionOverriding(boolean allowBeanDefinitionOverriding) {
		this.allowBeanDefinitionOverriding = allowBeanDefinitionOverriding;
	}

	
Sets if beans should be initialized lazily. Defaults to false. 
Params:
lazyInitialization – if initialization should be lazy
See Also:
BeanDefinition.setLazyInit(boolean)
Since:
2.2/**
	 * Sets if beans should be initialized lazily. Defaults to {@code false}.
	 * @param lazyInitialization if initialization should be lazy
	 * @since 2.2
	 * @see BeanDefinition#setLazyInit(boolean)
	 */
	public void setLazyInitialization(boolean lazyInitialization) {
		this.lazyInitialization = lazyInitialization;
	}

	
Sets if the application is headless and should not instantiate AWT. Defaults to true to prevent java icons appearing. 
Params:
headless – if the application is headless/**
	 * Sets if the application is headless and should not instantiate AWT. Defaults to
	 * {@code true} to prevent java icons appearing.
	 * @param headless if the application is headless
	 */
	public void setHeadless(boolean headless) {
		this.headless = headless;
	}

	
Sets if the created ApplicationContext should have a shutdown hook registered. Defaults to true to ensure that JVM shutdowns are handled gracefully. 
Params:
registerShutdownHook – if the shutdown hook should be registered/**
	 * Sets if the created {@link ApplicationContext} should have a shutdown hook
	 * registered. Defaults to {@code true} to ensure that JVM shutdowns are handled
	 * gracefully.
	 * @param registerShutdownHook if the shutdown hook should be registered
	 */
	public void setRegisterShutdownHook(boolean registerShutdownHook) {
		this.registerShutdownHook = registerShutdownHook;
	}

	
Sets the Banner instance which will be used to print the banner when no static banner file is provided. 
Params:
banner – the Banner instance to use/**
	 * Sets the {@link Banner} instance which will be used to print the banner when no
	 * static banner file is provided.
	 * @param banner the Banner instance to use
	 */
	public void setBanner(Banner banner) {
		this.banner = banner;
	}

	
Sets the mode used to display the banner when the application runs. Defaults to Banner.Mode.CONSOLE. 
Params:
bannerMode – the mode used to display the banner/**
	 * Sets the mode used to display the banner when the application runs. Defaults to
	 * {@code Banner.Mode.CONSOLE}.
	 * @param bannerMode the mode used to display the banner
	 */
	public void setBannerMode(Banner.Mode bannerMode) {
		this.bannerMode = bannerMode;
	}

	
Sets if the application information should be logged when the application starts. Defaults to true. 
Params:
logStartupInfo – if startup info should be logged./**
	 * Sets if the application information should be logged when the application starts.
	 * Defaults to {@code true}.
	 * @param logStartupInfo if startup info should be logged.
	 */
	public void setLogStartupInfo(boolean logStartupInfo) {
		this.logStartupInfo = logStartupInfo;
	}

	
Sets if a CommandLinePropertySource should be added to the application context in order to expose arguments. Defaults to true. 
Params:
addCommandLineProperties – if command line arguments should be exposed/**
	 * Sets if a {@link CommandLinePropertySource} should be added to the application
	 * context in order to expose arguments. Defaults to {@code true}.
	 * @param addCommandLineProperties if command line arguments should be exposed
	 */
	public void setAddCommandLineProperties(boolean addCommandLineProperties) {
		this.addCommandLineProperties = addCommandLineProperties;
	}

	
Sets if the ApplicationConversionService should be added to the application context's Environment. 
Params:
addConversionService – if the application conversion service should be added
Since:
2.1.0/**
	 * Sets if the {@link ApplicationConversionService} should be added to the application
	 * context's {@link Environment}.
	 * @param addConversionService if the application conversion service should be added
	 * @since 2.1.0
	 */
	public void setAddConversionService(boolean addConversionService) {
		this.addConversionService = addConversionService;
	}

	
Set default environment properties which will be used in addition to those in the existing Environment. 
Params:
defaultProperties – the additional properties to set/**
	 * Set default environment properties which will be used in addition to those in the
	 * existing {@link Environment}.
	 * @param defaultProperties the additional properties to set
	 */
	public void setDefaultProperties(Map<String, Object> defaultProperties) {
		this.defaultProperties = defaultProperties;
	}

	
Convenient alternative to setDefaultProperties(Map<String,Object>). 
Params:
defaultProperties – some Properties/**
	 * Convenient alternative to {@link #setDefaultProperties(Map)}.
	 * @param defaultProperties some {@link Properties}
	 */
	public void setDefaultProperties(Properties defaultProperties) {
		this.defaultProperties = new HashMap<>();
		for (Object key : Collections.list(defaultProperties.propertyNames())) {
			this.defaultProperties.put((String) key, defaultProperties.get(key));
		}
	}

	
Set additional profile values to use (on top of those set in system or command line
properties).
Params:
profiles – the additional profiles to set/**
	 * Set additional profile values to use (on top of those set in system or command line
	 * properties).
	 * @param profiles the additional profiles to set
	 */
	public void setAdditionalProfiles(String... profiles) {
		this.additionalProfiles = new LinkedHashSet<>(Arrays.asList(profiles));
	}

	
Sets the bean name generator that should be used when generating bean names.
Params:
beanNameGenerator – the bean name generator/**
	 * Sets the bean name generator that should be used when generating bean names.
	 * @param beanNameGenerator the bean name generator
	 */
	public void setBeanNameGenerator(BeanNameGenerator beanNameGenerator) {
		this.beanNameGenerator = beanNameGenerator;
	}

	
Sets the underlying environment that should be used with the created application
context.
Params:
environment – the environment/**
	 * Sets the underlying environment that should be used with the created application
	 * context.
	 * @param environment the environment
	 */
	public void setEnvironment(ConfigurableEnvironment environment) {
		this.isCustomEnvironment = true;
		this.environment = environment;
	}

	
Add additional items to the primary sources that will be added to an ApplicationContext when run(String...) is called. 
 The sources here are added to those that were set in the constructor. Most users should consider using getSources()/setSources(Set<String>) rather than calling this method. 
Params:
additionalPrimarySources – the additional primary sources to add
See Also:
SpringApplication(Class<?>...)
getSources()
setSources(Set<String>)
getAllSources()/**
	 * Add additional items to the primary sources that will be added to an
	 * ApplicationContext when {@link #run(String...)} is called.
	 * <p>
	 * The sources here are added to those that were set in the constructor. Most users
	 * should consider using {@link #getSources()}/{@link #setSources(Set)} rather than
	 * calling this method.
	 * @param additionalPrimarySources the additional primary sources to add
	 * @see #SpringApplication(Class...)
	 * @see #getSources()
	 * @see #setSources(Set)
	 * @see #getAllSources()
	 */
	public void addPrimarySources(Collection<Class<?>> additionalPrimarySources) {
		this.primarySources.addAll(additionalPrimarySources);
	}

	
Returns a mutable set of the sources that will be added to an ApplicationContext when run(String...) is called. 

Sources set here will be used in addition to any primary sources set in the
constructor.
See Also:
SpringApplication(Class<?>...)
getAllSources()
Returns:
the application sources./**
	 * Returns a mutable set of the sources that will be added to an ApplicationContext
	 * when {@link #run(String...)} is called.
	 * <p>
	 * Sources set here will be used in addition to any primary sources set in the
	 * constructor.
	 * @return the application sources.
	 * @see #SpringApplication(Class...)
	 * @see #getAllSources()
	 */
	public Set<String> getSources() {
		return this.sources;
	}

	
Set additional sources that will be used to create an ApplicationContext. A source
can be: a class name, package name, or an XML resource location.

Sources set here will be used in addition to any primary sources set in the
constructor.
Params:
sources – the application sources to set
See Also:
SpringApplication(Class<?>...)
getAllSources()/**
	 * Set additional sources that will be used to create an ApplicationContext. A source
	 * can be: a class name, package name, or an XML resource location.
	 * <p>
	 * Sources set here will be used in addition to any primary sources set in the
	 * constructor.
	 * @param sources the application sources to set
	 * @see #SpringApplication(Class...)
	 * @see #getAllSources()
	 */
	public void setSources(Set<String> sources) {
		Assert.notNull(sources, "Sources must not be null");
		this.sources = new LinkedHashSet<>(sources);
	}

	
Return an immutable set of all the sources that will be added to an ApplicationContext when run(String...) is called. This method combines any primary sources specified in the constructor with any additional ones that have been explicitly set. 
Returns:
an immutable set of all sources/**
	 * Return an immutable set of all the sources that will be added to an
	 * ApplicationContext when {@link #run(String...)} is called. This method combines any
	 * primary sources specified in the constructor with any additional ones that have
	 * been {@link #setSources(Set) explicitly set}.
	 * @return an immutable set of all sources
	 */
	public Set<Object> getAllSources() {
		Set<Object> allSources = new LinkedHashSet<>();
		if (!CollectionUtils.isEmpty(this.primarySources)) {
			allSources.addAll(this.primarySources);
		}
		if (!CollectionUtils.isEmpty(this.sources)) {
			allSources.addAll(this.sources);
		}
		return Collections.unmodifiableSet(allSources);
	}

	
Sets the ResourceLoader that should be used when loading resources. 
Params:
resourceLoader – the resource loader/**
	 * Sets the {@link ResourceLoader} that should be used when loading resources.
	 * @param resourceLoader the resource loader
	 */
	public void setResourceLoader(ResourceLoader resourceLoader) {
		Assert.notNull(resourceLoader, "ResourceLoader must not be null");
		this.resourceLoader = resourceLoader;
	}

	
Sets the type of Spring ApplicationContext that will be created. If not specified defaults to DEFAULT_SERVLET_WEB_CONTEXT_CLASS for web based applications or AnnotationConfigApplicationContext for non web based applications. 
Params:
applicationContextClass – the context class to set/**
	 * Sets the type of Spring {@link ApplicationContext} that will be created. If not
	 * specified defaults to {@link #DEFAULT_SERVLET_WEB_CONTEXT_CLASS} for web based
	 * applications or {@link AnnotationConfigApplicationContext} for non web based
	 * applications.
	 * @param applicationContextClass the context class to set
	 */
	public void setApplicationContextClass(Class<? extends ConfigurableApplicationContext> applicationContextClass) {
		this.applicationContextClass = applicationContextClass;
		this.webApplicationType = WebApplicationType.deduceFromApplicationContext(applicationContextClass);
	}

	
Sets the ApplicationContextInitializer that will be applied to the Spring ApplicationContext. 
Params:
initializers – the initializers to set/**
	 * Sets the {@link ApplicationContextInitializer} that will be applied to the Spring
	 * {@link ApplicationContext}.
	 * @param initializers the initializers to set
	 */
	public void setInitializers(Collection<? extends ApplicationContextInitializer<?>> initializers) {
		this.initializers = new ArrayList<>(initializers);
	}

	
Add ApplicationContextInitializers to be applied to the Spring ApplicationContext. 
Params:
initializers – the initializers to add/**
	 * Add {@link ApplicationContextInitializer}s to be applied to the Spring
	 * {@link ApplicationContext}.
	 * @param initializers the initializers to add
	 */
	public void addInitializers(ApplicationContextInitializer<?>... initializers) {
		this.initializers.addAll(Arrays.asList(initializers));
	}

	
Returns read-only ordered Set of the ApplicationContextInitializers that will be applied to the Spring ApplicationContext. 
Returns:
the initializers/**
	 * Returns read-only ordered Set of the {@link ApplicationContextInitializer}s that
	 * will be applied to the Spring {@link ApplicationContext}.
	 * @return the initializers
	 */
	public Set<ApplicationContextInitializer<?>> getInitializers() {
		return asUnmodifiableOrderedSet(this.initializers);
	}

	
Sets the ApplicationListeners that will be applied to the SpringApplication and registered with the ApplicationContext. 
Params:
listeners – the listeners to set/**
	 * Sets the {@link ApplicationListener}s that will be applied to the SpringApplication
	 * and registered with the {@link ApplicationContext}.
	 * @param listeners the listeners to set
	 */
	public void setListeners(Collection<? extends ApplicationListener<?>> listeners) {
		this.listeners = new ArrayList<>(listeners);
	}

	
Add ApplicationListeners to be applied to the SpringApplication and registered with the ApplicationContext. 
Params:
listeners – the listeners to add/**
	 * Add {@link ApplicationListener}s to be applied to the SpringApplication and
	 * registered with the {@link ApplicationContext}.
	 * @param listeners the listeners to add
	 */
	public void addListeners(ApplicationListener<?>... listeners) {
		this.listeners.addAll(Arrays.asList(listeners));
	}

	
Returns read-only ordered Set of the ApplicationListeners that will be applied to the SpringApplication and registered with the ApplicationContext . 
Returns:
the listeners/**
	 * Returns read-only ordered Set of the {@link ApplicationListener}s that will be
	 * applied to the SpringApplication and registered with the {@link ApplicationContext}
	 * .
	 * @return the listeners
	 */
	public Set<ApplicationListener<?>> getListeners() {
		return asUnmodifiableOrderedSet(this.listeners);
	}

	
Static helper that can be used to run a SpringApplication from the specified source using default settings. 
Params:
primarySource – the primary source to load
args – the application arguments (usually passed from a Java main method)
Returns:
the running ApplicationContext/**
	 * Static helper that can be used to run a {@link SpringApplication} from the
	 * specified source using default settings.
	 * @param primarySource the primary source to load
	 * @param args the application arguments (usually passed from a Java main method)
	 * @return the running {@link ApplicationContext}
	 */
	public static ConfigurableApplicationContext run(Class<?> primarySource, String... args) {
		return run(new Class<?>[] { primarySource }, args);
	}

	
Static helper that can be used to run a SpringApplication from the specified sources using default settings and user supplied arguments. 
Params:
primarySources – the primary sources to load
args – the application arguments (usually passed from a Java main method)
Returns:
the running ApplicationContext/**
	 * Static helper that can be used to run a {@link SpringApplication} from the
	 * specified sources using default settings and user supplied arguments.
	 * @param primarySources the primary sources to load
	 * @param args the application arguments (usually passed from a Java main method)
	 * @return the running {@link ApplicationContext}
	 */
	public static ConfigurableApplicationContext run(Class<?>[] primarySources, String[] args) {
		return new SpringApplication(primarySources).run(args);
	}

	
A basic main that can be used to launch an application. This method is useful when application sources are defined via a --spring.main.sources command line argument. 
 Most developers will want to define their own main method and call the run method instead. 
Params:
args – command line arguments
Throws:
Exception – if the application cannot be started
See Also:
run(Class<?>[], String[])
run(Class<?>, String...)/**
	 * A basic main that can be used to launch an application. This method is useful when
	 * application sources are defined via a {@literal --spring.main.sources} command line
	 * argument.
	 * <p>
	 * Most developers will want to define their own main method and call the
	 * {@link #run(Class, String...) run} method instead.
	 * @param args command line arguments
	 * @throws Exception if the application cannot be started
	 * @see SpringApplication#run(Class[], String[])
	 * @see SpringApplication#run(Class, String...)
	 */
	public static void main(String[] args) throws Exception {
		SpringApplication.run(new Class<?>[0], args);
	}

	
Static helper that can be used to exit a SpringApplication and obtain a code indicating success (0) or otherwise. Does not throw exceptions but should print stack traces of any encountered. Applies the specified ExitCodeGenerator in addition to any Spring beans that implement ExitCodeGenerator. In the case of multiple exit codes the highest value will be used (or if all values are negative, the lowest value will be used) 
Params:
context – the context to close if possible
exitCodeGenerators – exist code generators
Returns:
the outcome (0 if successful)/**
	 * Static helper that can be used to exit a {@link SpringApplication} and obtain a
	 * code indicating success (0) or otherwise. Does not throw exceptions but should
	 * print stack traces of any encountered. Applies the specified
	 * {@link ExitCodeGenerator} in addition to any Spring beans that implement
	 * {@link ExitCodeGenerator}. In the case of multiple exit codes the highest value
	 * will be used (or if all values are negative, the lowest value will be used)
	 * @param context the context to close if possible
	 * @param exitCodeGenerators exist code generators
	 * @return the outcome (0 if successful)
	 */
	public static int exit(ApplicationContext context, ExitCodeGenerator... exitCodeGenerators) {
		Assert.notNull(context, "Context must not be null");
		int exitCode = 0;
		try {
			try {
				ExitCodeGenerators generators = new ExitCodeGenerators();
				Collection<ExitCodeGenerator> beans = context.getBeansOfType(ExitCodeGenerator.class).values();
				generators.addAll(exitCodeGenerators);
				generators.addAll(beans);
				exitCode = generators.getExitCode();
				if (exitCode != 0) {
					context.publishEvent(new ExitCodeEvent(context, exitCode));
				}
			}
			finally {
				close(context);
			}
		}
		catch (Exception ex) {
			ex.printStackTrace();
			exitCode = (exitCode != 0) ? exitCode : 1;
		}
		return exitCode;
	}

	private static void close(ApplicationContext context) {
		if (context instanceof ConfigurableApplicationContext) {
			ConfigurableApplicationContext closable = (ConfigurableApplicationContext) context;
			closable.close();
		}
	}

	private static <E> Set<E> asUnmodifiableOrderedSet(Collection<E> elements) {
		List<E> list = new ArrayList<>(elements);
		list.sort(AnnotationAwareOrderComparator.INSTANCE);
		return new LinkedHashSet<>(list);
	}

}