Add custom LayoutFactory sample

Add a sample that shows how a custom LayoutFactory can be used with
both Maven and Gradle.

Closes gh-7263

spring-boot-samples/spring-boot-sample-custom-layout/src/test/java/sample/layout/GradeIT.java

@@ -0,0 +1,89 @@
+/*
+ * 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 sample.layout;
+
+import java.io.File;
+import java.io.FileReader;
+
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathExpression;
+import javax.xml.xpath.XPathFactory;
+
+import org.gradle.tooling.GradleConnector;
+import org.gradle.tooling.ProjectConnection;
+import org.gradle.tooling.internal.consumer.DefaultGradleConnector;
+import org.junit.Test;
+import org.xml.sax.InputSource;
+
+import org.springframework.util.FileCopyUtils;
+
+public class GradeIT {
+
+	@Test
+	public void sampleDefault() throws Exception {
+		test("default", "sample");
+	}
+
+	@Test
+	public void sampleCustom() throws Exception {
+		test("custom", "custom");
+	}
+
+	private void test(String name, String expected) throws Exception {
+		File projectDirectory = new File("target/gradleit/" + name);
+		File javaDirectory = new File(
+				"target/gradleit/" + name + "/src/main/java/org/test/");
+		projectDirectory.mkdirs();
+		javaDirectory.mkdirs();
+		File script = new File(projectDirectory, "build.gradle");
+		FileCopyUtils.copy(new File("src/it/" + name + "/build.gradle"), script);
+		FileCopyUtils.copy(
+				new File("src/it/" + name
+						+ "/src/main/java/org/test/SampleApplication.java"),
+				new File(javaDirectory, "SampleApplication.java"));
+		GradleConnector gradleConnector = GradleConnector.newConnector();
+		gradleConnector.useGradleVersion("2.9");
+		((DefaultGradleConnector) gradleConnector).embedded(true);
+		ProjectConnection project = gradleConnector.forProjectDirectory(projectDirectory)
+				.connect();
+		project.newBuild().forTasks("clean", "build")
+				.withArguments("-PbootVersion=" + getBootVersion()).run();
+		Verify.verify(
+				new File("target/gradleit/" + name + "/build/libs/" + name + ".jar"),
+				expected);
+	}
+
+	public static String getBootVersion() {
+		return evaluateExpression(
+				"/*[local-name()='project']/*[local-name()='version']" + "/text()");
+	}
+
+	private static String evaluateExpression(String expression) {
+		try {
+			XPathFactory xPathFactory = XPathFactory.newInstance();
+			XPath xpath = xPathFactory.newXPath();
+			XPathExpression expr = xpath.compile(expression);
+			String version = expr.evaluate(
+					new InputSource(new FileReader("target/dependencies-pom.xml")));
+			return version;
+		}
+		catch (Exception ex) {
+			throw new IllegalStateException("Failed to evaluate expression", ex);
+		}
+	}
+
+}

spring-boot-samples/spring-boot-sample-custom-layout/src/test/java/sample/layout/Verify.java

@@ -0,0 +1,45 @@
+/*
+ * 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 sample.layout;
+
+import java.io.File;
+import java.util.Enumeration;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipFile;
+
+public final class Verify {
+
+	private Verify() {
+	}
+
+	public static void verify(File file, String entry) throws Exception {
+		ZipFile zipFile = new ZipFile(file);
+		try {
+			Enumeration<? extends ZipEntry> entries = zipFile.entries();
+			while (entries.hasMoreElements()) {
+				if (entries.nextElement().getName().equals(entry)) {
+					return;
+				}
+			}
+			throw new AssertionError("No entry " + entry);
+		}
+		finally {
+			zipFile.close();
+		}
+	}
+
+}