Refactor to make LayoutType a true enum again

This makes the autocompletion for pom.xml and (maybe) build.gradle
easier for most users, but at the cost of a slightly odd API for
deriving Layout from LayoutType.

Author: Dave Syer

spring-boot-docs/src/main/asciidoc/build-tool-plugins.adoc

@@ -480,9 +480,12 @@ The following configuration options are available:
 |The name of the custom configuration.
 
 |`layout`
-|The type of archive, corresponding to how the dependencies are laid out inside
- (defaults to a guess based on the archive type). See
- <<build-tool-plugins-gradle-configuration-layouts,available layouts for more details>>.
+|The `LayoutType` of archive, corresponding to how the dependencies are laid out inside
+ (defaults to a guess based on the archive type).
+
+|`layoutFactory`
+|A factory for the actual `Layout` derived from the `LayoutType`. See 
+<<build-tool-plugins-gradle-configuration-layouts,available layouts for more details>>.
 
 |`requiresUnpack`
 |A list of dependencies (in the form "`groupId:artifactId`" that must be unpacked from
@@ -534,9 +537,9 @@ loader should be included or not. The following layouts are available:
 ==== Using a custom layout
 If you have custom requirements for how to arrange the dependencies and loader classes
 inside the repackaged jar, you can use a custom layout in addition to the built-in values.
-Any library which defines one or more `LayoutFactory` implementations and
-lists them in `META-INF/spring.factories` can be added to the build script dependencies
-and then the layout type becomes available in the `springBoot` configuration. For example
+Any library which defines one or more `LayoutFactory` implementations can be added to the 
+build script dependencies and then the layout type becomes available in the `springBoot` 
+configuration. For example
 
 [source,groovy,indent=0,subs="verbatim,attributes"]
 ----
@@ -556,7 +559,7 @@ buildscript {
 }
 
 springBoot {
-	layout = 'CUSTOM'
+	layoutFactory = new com.example.CustomLayoutFactory()
 }
 ----
 

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

@@ -26,7 +26,9 @@
 import org.gradle.api.plugins.JavaPlugin;
 
 import org.springframework.boot.gradle.buildinfo.BuildInfo;
+import org.springframework.boot.loader.tools.DefaultLayoutFactory;
 import org.springframework.boot.loader.tools.Layout;
+import org.springframework.boot.loader.tools.LayoutFactory;
 import org.springframework.boot.loader.tools.LayoutType;
 
 /**
@@ -89,7 +91,12 @@ public class SpringBootPluginExtension {
 	 * the MANIFEST.MF 'Main-Class' to be PropertiesLauncher. Gradle will coerce literal
 	 * String values to the correct type.
 	 */
-	String layout;
+	LayoutType layout;
+
+	/**
+	 * The layout factory to use to convert a layout type into an actual layout.
+	 */
+	LayoutFactory layoutFactory = new DefaultLayoutFactory();
 
 	/**
 	 * Libraries that must be unpacked from fat jars in order to run. Use Strings in the
@@ -143,10 +150,14 @@ public SpringBootPluginExtension(Project project) {
 
 	/**
 	 * Convenience method for use in a custom task.
+	 * @param file the file to use to guess the layout if necessary
 	 * @return the Layout to use or null if not explicitly set
 	 */
-	public Layout convertLayout() {
-		return (this.layout == null ? null : LayoutType.layout(this.layout));
+	public Layout convertLayout(File file) {
+		if (this.layout == null) {
+			this.layout = LayoutType.forFile(file);
+		}
+		return this.layoutFactory.getLayout(this.layout);
 	}
 
 	public String getMainClass() {
@@ -189,14 +200,22 @@ public void setBackupSource(boolean backupSource) {
 		this.backupSource = backupSource;
 	}
 
-	public String getLayout() {
+	public LayoutType getLayout() {
 		return this.layout;
 	}
 
-	public void setLayout(String layout) {
+	public void setLayout(LayoutType layout) {
 		this.layout = layout;
 	}
 
+	public LayoutFactory getLayoutFactory() {
+		return this.layoutFactory;
+	}
+
+	public void setLayoutFactory(LayoutFactory layoutFactory) {
+		this.layoutFactory = layoutFactory;
+	}
+
 	public Set<String> getRequiresUnpack() {
 		return this.requiresUnpack;
 	}

spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/repackage/RepackageTask.java

@@ -217,9 +217,7 @@ private void repackage(File file) {
 			}
 			Repackager repackager = new LoggingRepackager(file);
 			setMainClass(repackager);
-			if (this.extension.convertLayout() != null) {
-				repackager.setLayout(this.extension.convertLayout());
-			}
+			repackager.setLayout(this.extension.convertLayout(file));
 			repackager.setBackupSource(this.extension.isBackupSource());
 			try {
 				LaunchScript launchScript = getLaunchScript();

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

@@ -0,0 +1,44 @@
+/*
+ * Copyright 2012-2015 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;
+
+/**
+ * Default implementation of layout factory that looks up the enum value and maps it to a
+ * layout from {@link Layouts}.
+ *
+ * @author Dave Syer
+ *
+ */
+public class DefaultLayoutFactory implements LayoutFactory {
+
+	@Override
+	public Layout getLayout(LayoutType type) {
+		switch (type) {
+		case JAR:
+			return new Layouts.Jar();
+		case WAR:
+			return new Layouts.War();
+		case ZIP:
+			return new Layouts.Expanded();
+		case MODULE:
+			return new Layouts.Module();
+		default:
+			return new Layouts.None();
+		}
+	}
+
+}

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

@@ -24,8 +24,6 @@
  */
 public interface LayoutFactory {
 
-	Layout getLayout();
-
-	String getName();
+	Layout getLayout(LayoutType type);
 
 }

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

@@ -16,11 +16,7 @@
 
 package org.springframework.boot.loader.tools;
 
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-
-import org.springframework.core.io.support.SpringFactoriesLoader;
+import java.io.File;
 
 /**
  * Archive layout types.
@@ -32,70 +28,53 @@ public enum LayoutType {
 	/**
 	 * Jar Layout.
 	 */
-	JAR(new Layouts.Jar()),
+	JAR,
 
 	/**
 	 * War Layout.
 	 */
-	WAR(new Layouts.War()),
+	WAR,
 
 	/**
 	 * Zip Layout.
 	 */
-	ZIP(new Layouts.Expanded()),
+	ZIP,
 
 	/**
 	 * Dir Layout.
 	 */
-	DIR(new Layouts.Expanded()),
+	DIR,
 
 	/**
 	 * Module Layout.
 	 */
-	MODULE(new Layouts.Module()),
+	MODULE,
 
 	/**
 	 * No Layout.
 	 */
-	NONE(new Layouts.None());
-
-	private static Map<String, Layout> customTypes;
-
-	private final Layout layout;
+	NONE;
 
-	public Layout layout() {
-		return this.layout;
-	}
-
-	LayoutType(Layout layout) {
-		this.layout = layout;
-	}
 
-	public static Layout layout(String value) {
-		try {
-			return valueOf(value).layout();
+	/**
+	 * Return a layout type for the given source file.
+	 * @param file the source file
+	 * @return a {@link Layout}
+	 */
+	public static LayoutType forFile(File file) {
+		if (file == null) {
+			throw new IllegalArgumentException("File must not be null");
 		}
-		catch (IllegalArgumentException e) {
-			if (customTypes == null) {
-				customTypes = new HashMap<String, Layout>();
-				lookupCustomTypes();
-			}
-			Layout layout = customTypes.get(value);
-			if (layout == null) {
-				throw new IllegalArgumentException(
-						"Cannot resolve custom layout type: " + value);
-			}
-			return layout;
+		if (file.getName().toLowerCase().endsWith(".jar")) {
+			return JAR;
 		}
-	}
-
-	private static void lookupCustomTypes() {
-		ClassLoader classLoader = LayoutType.class.getClassLoader();
-		List<LayoutFactory> factories = SpringFactoriesLoader
-				.loadFactories(LayoutFactory.class, classLoader);
-		for (LayoutFactory factory : factories) {
-			customTypes.put(factory.getName(), factory.getLayout());
+		if (file.getName().toLowerCase().endsWith(".war")) {
+			return WAR;
+		}
+		if (file.isDirectory() || file.getName().toLowerCase().endsWith(".zip")) {
+			return ZIP;
 		}
+		throw new IllegalArgumentException("Unable to deduce layout for '" + file + "'");
 	}
 
 }

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

@@ -47,19 +47,7 @@ private Layouts() {
 	 * @return a {@link Layout}
 	 */
 	public static Layout forFile(File file) {
-		if (file == null) {
-			throw new IllegalArgumentException("File must not be null");
-		}
-		if (file.getName().toLowerCase().endsWith(".jar")) {
-			return new Jar();
-		}
-		if (file.getName().toLowerCase().endsWith(".war")) {
-			return new War();
-		}
-		if (file.isDirectory() || file.getName().toLowerCase().endsWith(".zip")) {
-			return new Expanded();
-		}
-		throw new IllegalStateException("Unable to deduce layout for '" + file + "'");
+		return new DefaultLayoutFactory().getLayout(LayoutType.forFile(file));
 	}
 
 	/**

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

@@ -26,28 +26,26 @@
  */
 public class LayoutTypeTests {
 
+	private LayoutFactory factory = new DefaultLayoutFactory();
+
 	@Test
 	public void standardType() {
-		assertThat(LayoutType.layout("DIR"))
-				.isEqualTo(LayoutType.valueOf("DIR").layout());
+		assertThat(this.factory.getLayout(LayoutType.DIR)).isNotNull();
 	}
 
 	@Test
 	public void customType() {
-		assertThat(LayoutType.layout("CUSTOM")).isNotNull();
+		this.factory = new TestLayoutFactory();
+		assertThat(this.factory.getLayout(LayoutType.MODULE)).isNotNull();
 	}
 
 	public static class TestLayoutFactory implements LayoutFactory {
 
 		@Override
-		public Layout getLayout() {
+		public Layout getLayout(LayoutType type) {
 			return new Layouts.Jar();
 		}
 
-		@Override
-		public String getName() {
-			return "CUSTOM";
-		}
 	}
 
 }

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

@@ -41,7 +41,9 @@
 import org.apache.maven.shared.artifact.filter.collection.ScopeFilter;
 
 import org.springframework.boot.loader.tools.DefaultLaunchScript;
+import org.springframework.boot.loader.tools.DefaultLayoutFactory;
 import org.springframework.boot.loader.tools.LaunchScript;
+import org.springframework.boot.loader.tools.LayoutFactory;
 import org.springframework.boot.loader.tools.LayoutType;
 import org.springframework.boot.loader.tools.Libraries;
 import org.springframework.boot.loader.tools.Repackager;
@@ -130,7 +132,14 @@ public class RepackageMojo extends AbstractDependencyFilterMojo {
 	 * @since 1.0
 	 */
 	@Parameter
-	private String layout;
+	private LayoutType layout;
+
+	/**
+	 * The type of the layout factory that converts layout type to an actual layout.
+	 * @since 1.0
+	 */
+	@Parameter
+	private LayoutFactory layoutFactory = new DefaultLayoutFactory();
 
 	/**
 	 * A list of the libraries that must be unpacked from fat jars in order to run.
@@ -225,9 +234,15 @@ private File getTargetFile() {
 	private Repackager getRepackager(File source) {
 		Repackager repackager = new LoggingRepackager(source, getLog());
 		repackager.setMainClass(this.mainClass);
-		if (this.layout != null) {
-			getLog().info("Layout: " + this.layout);
-			repackager.setLayout(LayoutType.layout(this.layout));
+		if (this.layout == null) {
+			this.layout = LayoutType.forFile(source);
+		}
+		getLog().info("Layout: " + this.layout);
+		try {
+			repackager.setLayout(this.layoutFactory.getLayout(this.layout));
+		}
+		catch (Exception e) {
+			throw new IllegalStateException("Cannot create layout", e);
 		}
 		return repackager;
 	}