Prefer @SpringBootApplication-annotated class when finding main class

Closes gh-6496

spring-boot-tools/spring-boot-antlib/src/main/java/org/springframework/boot/ant/FindMainClass.java

 /*
- * Copyright 2012-2015 the original author or authors.
+ * Copyright 2012-2016 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.
@@ -35,6 +35,8 @@ import org.springframework.util.StringUtils;
  */
 public class FindMainClass extends Task {
 
+	private static final String SPRING_BOOT_APPLICATION_CLASS_NAME = "org.springframework.boot.autoconfigure.SpringBootApplication";
+
 	private String mainClass;
 
 	private File classesRoot;
@@ -70,10 +72,11 @@ public class FindMainClass extends Task {
 		}
 		try {
 			if (this.classesRoot.isDirectory()) {
-				return MainClassFinder.findSingleMainClass(this.classesRoot);
+				return MainClassFinder.findSingleMainClass(this.classesRoot,
+						SPRING_BOOT_APPLICATION_CLASS_NAME);
 			}
-			return MainClassFinder.findSingleMainClass(new JarFile(this.classesRoot),
-					"/");
+			return MainClassFinder.findSingleMainClass(new JarFile(this.classesRoot), "/",
+					SPRING_BOOT_APPLICATION_CLASS_NAME);
 		}
 		catch (IOException ex) {
 			throw new BuildException(ex);

spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/run/FindMainClassTask.java

@@ -41,6 +41,8 @@ import org.springframework.boot.loader.tools.MainClassFinder;
  */
 public class FindMainClassTask extends DefaultTask {
 
+	private static final String SPRING_BOOT_APPLICATION_CLASS_NAME = "org.springframework.boot.autoconfigure.SpringBootApplication";
+
 	@Input
 	private SourceSetOutput mainClassSourceSetOutput;
 
@@ -105,7 +107,8 @@ public class FindMainClassTask extends DefaultTask {
 						+ this.mainClassSourceSetOutput.getClassesDir());
 				try {
 					mainClass = MainClassFinder.findSingleMainClass(
-							this.mainClassSourceSetOutput.getClassesDir());
+							this.mainClassSourceSetOutput.getClassesDir(),
+							SPRING_BOOT_APPLICATION_CLASS_NAME);
 					project.getLogger().info("Computed main class: " + mainClass);
 				}
 				catch (IOException ex) {

spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/Repackager.java

@@ -59,6 +59,8 @@ public class Repackager {
 
 	private static final long FIND_WARNING_TIMEOUT = TimeUnit.SECONDS.toMillis(10);
 
+	private static final String SPRING_BOOT_APPLICATION_CLASS_NAME = "org.springframework.boot.autoconfigure.SpringBootApplication";
+
 	private List<MainClassTimeoutWarningListener> mainClassTimeoutListeners = new ArrayList<MainClassTimeoutWarningListener>();
 
 	private String mainClass;
@@ -383,7 +385,7 @@ public class Repackager {
 
 	protected String findMainMethod(JarFile source) throws IOException {
 		return MainClassFinder.findSingleMainClass(source,
-				this.layout.getClassesLocation());
+				this.layout.getClassesLocation(), SPRING_BOOT_APPLICATION_CLASS_NAME);
 	}
 
 	private void renameFile(File file, File dest) {

spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/MainClassFinderTests.java

@@ -26,7 +26,9 @@ import org.junit.Test;
 import org.junit.rules.ExpectedException;
 import org.junit.rules.TemporaryFolder;
 
-import org.springframework.boot.loader.tools.MainClassFinder.ClassNameCallback;
+import org.springframework.boot.loader.tools.MainClassFinder.MainClass;
+import org.springframework.boot.loader.tools.MainClassFinder.MainClassCallback;
+import org.springframework.boot.loader.tools.sample.AnnotatedClassWithMainMethod;
 import org.springframework.boot.loader.tools.sample.ClassWithMainMethod;
 import org.springframework.boot.loader.tools.sample.ClassWithoutMainMethod;
 
@@ -87,6 +89,16 @@ public class MainClassFinderTests {
 		MainClassFinder.findSingleMainClass(this.testJarFile.getJarFile(), "");
 	}
 
+	@Test
+	public void findSingleJarSearchPrefersAnnotatedMainClass() throws Exception {
+		this.testJarFile.addClass("a/B.class", ClassWithMainMethod.class);
+		this.testJarFile.addClass("a/b/c/E.class", AnnotatedClassWithMainMethod.class);
+		String mainClass = MainClassFinder.findSingleMainClass(
+				this.testJarFile.getJarFile(), "",
+				"org.springframework.boot.loader.tools.sample.SomeApplication");
+		assertThat(mainClass).isEqualTo("a.b.c.E");
+	}
+
 	@Test
 	public void findMainClassInJarSubLocation() throws Exception {
 		this.testJarFile.addClass("a/B.class", ClassWithMainMethod.class);
@@ -132,6 +144,16 @@ public class MainClassFinderTests {
 		MainClassFinder.findSingleMainClass(this.testJarFile.getJarSource());
 	}
 
+	@Test
+	public void findSingleFolderSearchPrefersAnnotatedMainClass() throws Exception {
+		this.testJarFile.addClass("a/B.class", ClassWithMainMethod.class);
+		this.testJarFile.addClass("a/b/c/E.class", AnnotatedClassWithMainMethod.class);
+		String mainClass = MainClassFinder.findSingleMainClass(
+				this.testJarFile.getJarSource(),
+				"org.springframework.boot.loader.tools.sample.SomeApplication");
+		assertThat(mainClass).isEqualTo("a.b.c.E");
+	}
+
 	@Test
 	public void doWithFolderMainMethods() throws Exception {
 		this.testJarFile.addClass("a/b/c/D.class", ClassWithMainMethod.class);
@@ -150,17 +172,17 @@ public class MainClassFinderTests {
 		this.testJarFile.addClass("a/b/F.class", ClassWithoutMainMethod.class);
 		this.testJarFile.addClass("a/b/G.class", ClassWithMainMethod.class);
 		ClassNameCollector callback = new ClassNameCollector();
-		MainClassFinder.doWithMainClasses(this.testJarFile.getJarFile(), "", callback);
+		MainClassFinder.doWithMainClasses(this.testJarFile.getJarFile(), null, callback);
 		assertThat(callback.getClassNames().toString()).isEqualTo("[a.b.G, a.b.c.D]");
 	}
 
-	private static class ClassNameCollector implements ClassNameCallback<Object> {
+	private static class ClassNameCollector implements MainClassCallback<Object> {
 
 		private final List<String> classNames = new ArrayList<String>();
 
 		@Override
-		public Object doWith(String className) {
-			this.classNames.add(className);
+		public Object doWith(MainClass mainClass) {
+			this.classNames.add(mainClass.getName());
 			return null;
 		}
 

spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/sample/AnnotatedClassWithMainMethod.java

+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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.boot.loader.tools.sample;
+
+/**
+ * Sample annotated class with a main method.
+ *
+ * @author Andy Wilkinson
+ */
+@SomeApplication
+public class AnnotatedClassWithMainMethod {
+
+	public void run() {
+		System.out.println("Hello World");
+	}
+
+	public static void main(String[] args) {
+		new AnnotatedClassWithMainMethod().run();
+	}
+
+}

spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/sample/SomeApplication.java

+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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.boot.loader.tools.sample;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Test annotation for a main application class.
+ *
+ * @author Andy Wilkinson
+ */
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+@interface SomeApplication {
+
+}

spring-boot-tools/spring-boot-maven-plugin/src/main/java/org/springframework/boot/maven/AbstractRunMojo.java

@@ -52,6 +52,8 @@ import org.springframework.boot.loader.tools.MainClassFinder;
  */
 public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 
+	private static final String SPRING_BOOT_APPLICATION_CLASS_NAME = "org.springframework.boot.autoconfigure.SpringBootApplication";
+
 	private static final String SPRING_LOADED_AGENT_CLASS_NAME = "org.springsource.loaded.agent.SpringLoadedAgent";
 
 	/**
@@ -374,7 +376,8 @@ public abstract class AbstractRunMojo extends AbstractDependencyFilterMojo {
 		String mainClass = this.mainClass;
 		if (mainClass == null) {
 			try {
-				mainClass = MainClassFinder.findSingleMainClass(this.classesDirectory);
+				mainClass = MainClassFinder.findSingleMainClass(this.classesDirectory,
+						SPRING_BOOT_APPLICATION_CLASS_NAME);
 			}
 			catch (IOException ex) {
 				throw new MojoExecutionException(ex.getMessage(), ex);