Optimize ApplicationContextInitializer handling

- Perform early check whether any ACI classes have been declared and
   exit immediately if not, avoiding any other processing

 - Polish method names in ContextLoaderTests

Issue: SPR-8991

org.springframework.web.servlet/src/test/java/org/springframework/web/context/ContextLoaderTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -116,7 +116,7 @@ public final class ContextLoaderTests {
 	}
 
 	@Test
-	public void testContextLoaderListenerWithRegisteredContextConfigurer() {
+	public void testContextLoaderListenerWithRegisteredContextInitializer() {
 		MockServletContext sc = new MockServletContext("");
 		sc.addInitParameter(ContextLoader.CONFIG_LOCATION_PARAM,
 				"org/springframework/web/context/WEB-INF/ContextLoaderTests-acc-context.xml");
@@ -132,7 +132,7 @@ public final class ContextLoaderTests {
 	}
 
 	@Test
-	public void testContextLoaderListenerWithUnkownContextConfigurer() {
+	public void testContextLoaderListenerWithUnkownContextInitializer() {
 		MockServletContext sc = new MockServletContext("");
 		// config file doesn't matter.  just a placeholder
 		sc.addInitParameter(ContextLoader.CONFIG_LOCATION_PARAM,

org.springframework.web/src/main/java/org/springframework/web/context/ContextLoader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2011 the original author or authors.
+ * Copyright 2002-2012 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.
@@ -23,11 +23,11 @@ import java.util.List;
 import java.util.Map;
 import java.util.Properties;
 import java.util.concurrent.ConcurrentHashMap;
+
 import javax.servlet.ServletContext;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
-
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.access.BeanFactoryLocator;
 import org.springframework.beans.factory.access.BeanFactoryReference;
@@ -463,11 +463,18 @@ public class ContextLoader {
 	 * @see ApplicationContextInitializer#initialize(ConfigurableApplicationContext)
 	 */
 	protected void customizeContext(ServletContext servletContext, ConfigurableWebApplicationContext applicationContext) {
+		List<Class<ApplicationContextInitializer<ConfigurableApplicationContext>>> initializerClasses =
+				determineContextInitializerClasses(servletContext);
+
+		if (initializerClasses.size() == 0) {
+			// no ApplicationContextInitializers have been declared -> nothing to do
+			return;
+		}
+
 		ArrayList<ApplicationContextInitializer<ConfigurableApplicationContext>> initializerInstances =
 			new ArrayList<ApplicationContextInitializer<ConfigurableApplicationContext>>();
 
-		for (Class<ApplicationContextInitializer<ConfigurableApplicationContext>> initializerClass :
-				determineContextInitializerClasses(servletContext)) {
+		for (Class<ApplicationContextInitializer<ConfigurableApplicationContext>> initializerClass : initializerClasses) {
 			Class<?> contextClass = applicationContext.getClass();
 			Class<?> initializerContextClass =
 				GenericTypeResolver.resolveTypeArgument(initializerClass, ApplicationContextInitializer.class);