Provide a flag to disable SpEL support

This commit introduces a spring.spel.ignore flag which
when set to true avoid initializing SpEL infrastructure.

A typical use case is optimizing GraalVM native image footprint.

Closes spring-projectsgh-25153

spring-context/src/main/java/org/springframework/context/event/ApplicationListenerMethodAdapter.java

@@ -142,7 +142,7 @@ private static int resolveOrder(Method method) {
 	/**
 	 * Initialize this instance.
 	 */
-	void init(ApplicationContext applicationContext, EventExpressionEvaluator evaluator) {
+	void init(ApplicationContext applicationContext, @Nullable EventExpressionEvaluator evaluator) {
 		this.applicationContext = applicationContext;
 		this.evaluator = evaluator;
 	}

spring-context/src/main/java/org/springframework/context/event/EventListenerMethodProcessor.java

@@ -39,7 +39,9 @@
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.ApplicationListener;
 import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.support.AbstractApplicationContext;
 import org.springframework.core.MethodIntrospector;
+import org.springframework.core.SpringProperties;
 import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.core.annotation.AnnotationUtils;
@@ -63,6 +65,9 @@
 public class EventListenerMethodProcessor
 		implements SmartInitializingSingleton, ApplicationContextAware, BeanFactoryPostProcessor {
 
+	private static final boolean shouldIgnoreSpel =
+			SpringProperties.getFlag(AbstractApplicationContext.IGNORE_SPEL_PROPERTY_NAME);
+
 	protected final Log logger = LogFactory.getLog(getClass());
 
 	@Nullable
@@ -74,11 +79,18 @@ public class EventListenerMethodProcessor
 	@Nullable
 	private List<EventListenerFactory> eventListenerFactories;
 
-	private final EventExpressionEvaluator evaluator = new EventExpressionEvaluator();
+	@Nullable
+	private EventExpressionEvaluator evaluator;
 
 	private final Set<Class<?>> nonAnnotatedClasses = Collections.newSetFromMap(new ConcurrentHashMap<>(64));
 
 
+	public EventListenerMethodProcessor() {
+		if (!shouldIgnoreSpel) {
+			this.evaluator = new EventExpressionEvaluator();
+		}
+	}
+
 	@Override
 	public void setApplicationContext(ApplicationContext applicationContext) {
 		Assert.isTrue(applicationContext instanceof ConfigurableApplicationContext,

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -67,6 +67,7 @@
 import org.springframework.context.weaving.LoadTimeWeaverAware;
 import org.springframework.context.weaving.LoadTimeWeaverAwareProcessor;
 import org.springframework.core.ResolvableType;
+import org.springframework.core.SpringProperties;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.env.ConfigurableEnvironment;
@@ -152,6 +153,15 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 	 */
 	public static final String APPLICATION_EVENT_MULTICASTER_BEAN_NAME = "applicationEventMulticaster";
 
+	/**
+	 * System property that instructs Spring to ignore SpEL, i.e.
+	 * to not initialize the SpEL infrastructure.
+	 * <p>The default is "false".
+	 */
+	public static final String IGNORE_SPEL_PROPERTY_NAME = "spring.spel.ignore";
+
+	private static final boolean shouldIgnoreSpel = SpringProperties.getFlag(IGNORE_SPEL_PROPERTY_NAME);
+
 
 	static {
 		// Eagerly load the ContextClosedEvent class to avoid weird classloader issues
@@ -647,7 +657,9 @@ protected ConfigurableListableBeanFactory obtainFreshBeanFactory() {
 	protected void prepareBeanFactory(ConfigurableListableBeanFactory beanFactory) {
 		// Tell the internal bean factory to use the context's class loader etc.
 		beanFactory.setBeanClassLoader(getClassLoader());
-		beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
+		if (!shouldIgnoreSpel) {
+			beanFactory.setBeanExpressionResolver(new StandardBeanExpressionResolver(beanFactory.getBeanClassLoader()));
+		}
 		beanFactory.addPropertyEditorRegistrar(new ResourceEditorRegistrar(this, getEnvironment()));
 
 		// Configure the bean factory with context callbacks.