Permit AOT-generated code to run on the JVM as well

This commit updates the codebase so that AOT-generated code can run on
the JVM in an opt-in fashion alongside the existing support of native
images.

When optimizations have been generated, setting the "spring.aot.enabled"
spring property (JVM or spring.properties) allows to opt-in for that
behavior on the JVM.

Closes gh-31244

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/ApplicationContextFactory.java

@@ -18,11 +18,11 @@ package org.springframework.boot;
 
 import java.util.function.Supplier;
 
+import org.springframework.aot.AotDetector;
 import org.springframework.beans.BeanUtils;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.support.GenericApplicationContext;
-import org.springframework.core.NativeDetector;
 import org.springframework.core.io.support.SpringFactoriesLoader;
 
 /**
@@ -51,7 +51,7 @@ public interface ApplicationContextFactory {
 					return context;
 				}
 			}
-			return NativeDetector.inNativeImage() ? new GenericApplicationContext()
+			return AotDetector.useGeneratedArtifacts() ? new GenericApplicationContext()
 					: new AnnotationConfigApplicationContext();
 		}
 		catch (Exception ex) {

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

@@ -32,6 +32,7 @@ import java.util.stream.Collectors;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import org.springframework.aot.AotDetector;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.CachedIntrospectionResults;
 import org.springframework.beans.factory.config.BeanDefinition;
@@ -59,10 +60,10 @@ import org.springframework.context.annotation.AnnotationConfigApplicationContext
 import org.springframework.context.annotation.AnnotationConfigUtils;
 import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
 import org.springframework.context.annotation.ConfigurationClassPostProcessor;
+import org.springframework.context.aot.ApplicationContextAotInitializer;
 import org.springframework.context.support.AbstractApplicationContext;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.core.GenericTypeResolver;
-import org.springframework.core.NativeDetector;
 import org.springframework.core.Ordered;
 import org.springframework.core.annotation.AnnotationAwareOrderComparator;
 import org.springframework.core.annotation.Order;
@@ -401,7 +402,7 @@ public class SpringApplication {
 			context.addBeanFactoryPostProcessor(new LazyInitializationBeanFactoryPostProcessor());
 		}
 		context.addBeanFactoryPostProcessor(new PropertySourceOrderingBeanFactoryPostProcessor(context));
-		if (!NativeDetector.inNativeImage()) {
+		if (!AotDetector.useGeneratedArtifacts()) {
 			// Load the sources
 			Set<Object> sources = getAllSources();
 			Assert.notEmpty(sources, "Sources must not be empty");
@@ -411,18 +412,13 @@ public class SpringApplication {
 	}
 
 	private void addAotGeneratedInitializerIfNecessary(List<ApplicationContextInitializer<?>> initializers) {
-		if (NativeDetector.inNativeImage()) {
+		if (AotDetector.useGeneratedArtifacts()) {
-			try {
+			String initializerClassName = this.mainApplicationClass.getName() + "__ApplicationContextInitializer";
-				Class<?> initializerClass = Class.forName(
+			if (logger.isDebugEnabled()) {
-						this.mainApplicationClass.getName() + "__ApplicationContextInitializer", true,
+				logger.debug("Using AOT generated initializer: " + initializerClassName);
-						getClassLoader());
-				ApplicationContextInitializer<?> initializer = (ApplicationContextInitializer<?>) initializerClass
-						.getDeclaredConstructor().newInstance();
-				initializers.add(0, initializer);
-			}
-			catch (Exception ex) {
-				throw new IllegalArgumentException("Failed to load AOT-generated ApplicationContextInitializer", ex);
 			}
+			initializers.add(0,
+					(context) -> new ApplicationContextAotInitializer().initialize(context, initializerClassName));
 		}
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/ReactiveWebServerApplicationContextFactory.java

@@ -16,10 +16,10 @@
 
 package org.springframework.boot.web.reactive.context;
 
+import org.springframework.aot.AotDetector;
 import org.springframework.boot.ApplicationContextFactory;
 import org.springframework.boot.WebApplicationType;
 import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.core.NativeDetector;
 
 /**
  * {@link ApplicationContextFactory} registered in {@code spring.factories} to support
@@ -36,7 +36,7 @@ class ReactiveWebServerApplicationContextFactory implements ApplicationContextFa
 		if (webApplicationType != WebApplicationType.REACTIVE) {
 			return null;
 		}
-		return NativeDetector.inNativeImage() ? new ReactiveWebServerApplicationContext()
+		return AotDetector.useGeneratedArtifacts() ? new ReactiveWebServerApplicationContext()
 				: new AnnotationConfigReactiveWebServerApplicationContext();
 	}
 

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/context/ServletWebServerApplicationContextFactory.java

@@ -16,10 +16,10 @@
 
 package org.springframework.boot.web.servlet.context;
 
+import org.springframework.aot.AotDetector;
 import org.springframework.boot.ApplicationContextFactory;
 import org.springframework.boot.WebApplicationType;
 import org.springframework.context.ConfigurableApplicationContext;
-import org.springframework.core.NativeDetector;
 
 /**
  * {@link ApplicationContextFactory} registered in {@code spring.factories} to support
@@ -36,7 +36,7 @@ class ServletWebServerApplicationContextFactory implements ApplicationContextFac
 		if (webApplicationType != WebApplicationType.SERVLET) {
 			return null;
 		}
-		return NativeDetector.inNativeImage() ? new ServletWebServerApplicationContext()
+		return AotDetector.useGeneratedArtifacts() ? new ServletWebServerApplicationContext()
 				: new AnnotationConfigServletWebServerApplicationContext();
 	}