Move Layout into adapter class

pr comments, mv package, make work locally.

revert pom change to parent

Rm provided scope - this is problematic for spring-boot-maven plugin to build jar

Detach sample from spring-cloud-function-parent

Update readmes

cleanup

Add comment

fix javadoc
Resolves #518

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/main/java/org/springframework/cloud/function/adapter/gcp/GcfJarLauncher.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright 2018-2020 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.cloud.function.adapter.gcp;
+
+import com.google.cloud.functions.HttpFunction;
+import com.google.cloud.functions.HttpRequest;
+import com.google.cloud.functions.HttpResponse;
+
+import org.springframework.boot.loader.JarLauncher;
+import org.springframework.boot.loader.jar.JarFile;
+
+/**
+ * The launcher class written at the top-level of the output JAR to be deployed to
+ * Google Cloud Functions. This is the entry point to the function when run from JAR.
+ *
+ * @author Ray Tsang
+ * @author Daniel Zou
+ */
+public class GcfJarLauncher extends JarLauncher implements HttpFunction {
+
+	private final ClassLoader loader;
+
+	private final HttpFunction delegate;
+
+	public GcfJarLauncher() throws Exception {
+		JarFile.registerUrlProtocolHandler();
+
+		this.loader = createClassLoader(getClassPathArchivesIterator());
+
+		Class<?> clazz = this.loader
+			.loadClass("org.springframework.cloud.function.adapter.gcp.FunctionInvoker");
+		this.delegate = (HttpFunction) clazz.getConstructor().newInstance();
+	}
+	@Override
+	public void service(HttpRequest httpRequest, HttpResponse httpResponse) throws Exception {
+		Thread.currentThread().setContextClassLoader(this.loader);
+		delegate.service(httpRequest, httpResponse);
+	}
+}
+

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/main/java/org/springframework/cloud/function/adapter/gcp/layout/GcfJarLayout.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2018-2020 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.cloud.function.adapter.gcp.layout;
+
+import java.io.IOException;
+
+import org.springframework.boot.loader.tools.CustomLoaderLayout;
+import org.springframework.boot.loader.tools.Layouts;
+import org.springframework.boot.loader.tools.LoaderClassesWriter;
+import org.springframework.cloud.function.adapter.gcp.GcfJarLauncher;
+
+/**
+ * A custom JAR Layout that writes GCF adapter classes to the top-level of the output JAR
+ * for deploying to GCF.
+ *
+ * @author Ray Tsang
+ * @author Daniel Zou
+ */
+public class GcfJarLayout extends Layouts.Jar implements CustomLoaderLayout {
+
+	private static final String LAUNCHER_NAME = GcfJarLauncher.class.getCanonicalName();
+
+	@Override
+	public String getLauncherClassName() {
+		return LAUNCHER_NAME;
+	}
+
+	@Override
+	public boolean isExecutable() {
+		return false;
+	}
+
+	@Override
+	public void writeLoadedClasses(LoaderClassesWriter writer) throws IOException {
+		writer.writeLoaderClasses();
+
+		String jarName = LAUNCHER_NAME.replaceAll("\\.", "/") + ".class";
+		writer.writeEntry(
+			jarName, GcfJarLauncher.class.getResourceAsStream("/" + jarName));
+	}
+}

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/main/java/org/springframework/cloud/function/adapter/gcp/layout/GcfJarLayoutFactory.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2018-2020 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.cloud.function.adapter.gcp.layout;
+
+import java.io.File;
+
+import org.springframework.boot.loader.tools.Layout;
+import org.springframework.boot.loader.tools.LayoutFactory;
+
+/**
+ * Factory boilerplate class that constructs {@link GcfJarLayout}.
+ *
+ * @author Ray Tsang
+ * @author Daniel Zou
+ */
+public class GcfJarLayoutFactory implements LayoutFactory {
+
+	@Override
+	public Layout getLayout(File source) {
+		return new GcfJarLayout();
+	}
+}

spring-cloud-function-adapters/spring-cloud-function-adapter-gcp/src/main/resources/META-INF/spring.factories

@@ -0,0 +1,2 @@
+org.springframework.boot.loader.tools.LayoutFactory=\
+org.springframework.cloud.function.adapter.gcp.layout.GcfJarLayoutFactory