Simplify WebApplicationContext class guard

See gh-3856

Author: philwebb

spring-boot-samples/spring-boot-sample-simple/src/main/java/sample/simple/SampleSimpleApplication.java

@@ -20,6 +20,7 @@
 import org.springframework.boot.CommandLineRunner;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 
 import sample.simple.service.HelloWorldService;
 
@@ -39,6 +40,9 @@ public void run(String... args) {
 	}
 
 	public static void main(String[] args) throws Exception {
+		SpringApplication application = new SpringApplication(
+				SampleSimpleApplication.class);
+		application.setApplicationContextClass(AnnotationConfigApplicationContext.class);
 		SpringApplication.run(SampleSimpleApplication.class, args);
 	}
 }

spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -227,12 +227,21 @@ private void initialize(Object[] sources) {
 		if (sources != null && sources.length > 0) {
 			this.sources.addAll(Arrays.asList(sources));
 		}
-		this.webEnvironment = isSpringWebAvailable();
+		this.webEnvironment = deduceWebEnvironment();
 		setInitializers((Collection) getSpringFactoriesInstances(ApplicationContextInitializer.class));
 		setListeners((Collection) getSpringFactoriesInstances(ApplicationListener.class));
 		this.mainApplicationClass = deduceMainApplicationClass();
 	}
 
+	private boolean deduceWebEnvironment() {
+		for (String className : WEB_ENVIRONMENT_CLASSES) {
+			if (!ClassUtils.isPresent(className, null)) {
+				return false;
+			}
+		}
+		return true;
+	}
+
 	private Class<?> deduceMainApplicationClass() {
 		try {
 			StackTraceElement[] stackTrace = new RuntimeException().getStackTrace();
@@ -864,12 +873,20 @@ public void setResourceLoader(ResourceLoader resourceLoader) {
 	public void setApplicationContextClass(
 			Class<? extends ConfigurableApplicationContext> applicationContextClass) {
 		this.applicationContextClass = applicationContextClass;
-		if (!isSpringWebAvailable() || !WebApplicationContext.class.isAssignableFrom(
-				applicationContextClass)) {
+		if (!isWebApplicationContext(applicationContextClass)) {
 			this.webEnvironment = false;
 		}
 	}
 
+	private boolean isWebApplicationContext(Class<?> applicationContextClass) {
+		try {
+			return WebApplicationContext.class.isAssignableFrom(applicationContextClass);
+		}
+		catch (NoClassDefFoundError ex) {
+			return false;
+		}
+	}
+
 	/**
 	 * Sets the {@link ApplicationContextInitializer} that will be applied to the Spring
 	 * {@link ApplicationContext}.
@@ -928,15 +945,6 @@ public Set<ApplicationListener<?>> getListeners() {
 		return asUnmodifiableOrderedSet(this.listeners);
 	}
 
-	private boolean isSpringWebAvailable() {
-		for (String className : WEB_ENVIRONMENT_CLASSES) {
-			if (!ClassUtils.isPresent(className, null)) {
-				return false;
-			}
-		}
-		return true;
-	}
-
 	/**
 	 * Static helper that can be used to run a {@link SpringApplication} from the
 	 * specified source using default settings.