SpringBootFatJarMain only dependency is spring-boot-loader

Closes gh-91

Author: rwinch

spring-boot-testjars/build.gradle

@@ -22,6 +22,7 @@ checkstyle {
 
 dependencies {
 	checkstyle("io.spring.javaformat:spring-javaformat-checkstyle:0.0.40")
+	compileOnly 'org.springframework.boot:spring-boot-loader'
 	implementation platform('org.springframework.boot:spring-boot-dependencies:3.4.0')
 	implementation 'org.apache.commons:commons-exec:1.3'
 	implementation 'org.springframework:spring-test'

spring-boot-testjars/src/main/java/org/springframework/experimental/boot/server/exec/detector/ClassUtils.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2024 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.experimental.boot.server.exec.detector;
+
+import org.springframework.lang.Nullable;
+
+final class ClassUtils {
+
+	/**
+	 * Wrapper for Class.forName to allow mocking in tests. Note that we cannot use
+	 * Spring's ClassUtils because it will not be available on the classpath.
+	 * @param name the name of the Class
+	 * @param classLoader the class loader to use (can be {@code null}, which indicates
+	 * the default class loader)
+	 * @return a class instance for the supplied name
+	 * @throws ClassNotFoundException if the class was not found
+	 * @throws LinkageError if the class file could not be loaded
+	 * @see Class#forName(String, boolean, ClassLoader)
+	 */
+	static Class<?> forName(String name, @Nullable ClassLoader classLoader)
+			throws ClassNotFoundException, LinkageError {
+
+		if (name == null) {
+			throw new IllegalArgumentException("name must not be null");
+		}
+
+		return Class.forName(name, false, classLoader);
+	}
+
+	private ClassUtils() {
+	}
+
+}

spring-boot-testjars/src/main/java/org/springframework/experimental/boot/server/exec/detector/SpringBootFatJarMain.java

@@ -18,12 +18,7 @@
 
 import java.lang.reflect.InvocationTargetException;
 
-import org.apache.commons.logging.Log;
-import org.apache.commons.logging.LogFactory;
-
-import org.springframework.core.log.LogMessage;
-import org.springframework.experimental.boot.server.exec.imports.GenericSpringBootApplicationMain;
-import org.springframework.util.ClassUtils;
+import org.springframework.boot.loader.log.DebugLogger;
 
 /**
  * Detect which JarLauncher main class to use, and call its {@code main(String[] args)}
@@ -37,7 +32,7 @@
  */
 public class SpringBootFatJarMain {
 
-	private static Log log = LogFactory.getLog(SpringBootFatJarMain.class);
+	private static DebugLogger debug = DebugLogger.get(SpringBootFatJarMain.class);
 
 	static final String SPRING_BOOT_32_PLUS_LAUNCHER_CLASSNAME = "org.springframework.boot.loader.launch.JarLauncher";
 
@@ -59,17 +54,16 @@ public static void main(String[] args) {
 	}
 
 	private static boolean runMain(String className, String[] args, String description) {
-		log.debug(LogMessage.format("Trying to run as %s using %s.main(String[])", description, className));
+		debug.log("Trying to run as %s using %s.main(String[])", description, className);
 		try {
-			Class<?> jarLauncher = ClassUtils.forName(className,
-					GenericSpringBootApplicationMain.class.getClassLoader());
+			Class<?> jarLauncher = ClassUtils.forName(className, SpringBootFatJarMain.class.getClassLoader());
 			var mainMethod = jarLauncher.getMethod("main", String[].class);
 			mainMethod.invoke(null, (Object) args);
-			log.debug(LogMessage.format("Successfully ran as %s", description));
+			debug.log("Successfully ran as %s", description);
 			return true;
 		}
 		catch (ClassNotFoundException ex) {
-			log.debug(LogMessage.format("Failed to run as %s", description), ex);
+			debug.log("Failed to run as %s", description, ex);
 		}
 		catch (NoSuchMethodException | InvocationTargetException | IllegalAccessException ex) {
 			throw new RuntimeException(ex);

spring-boot-testjars/src/test/java/org/springframework/experimental/boot/server/exec/detector/SpringBootFatJarMainTests.java

@@ -20,8 +20,6 @@
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
 
-import org.springframework.util.ClassUtils;
-
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.mockito.ArgumentMatchers.any;