Add packaging abstraction

Closes gh-815

Co-authored-by: Stephane Nicoll <snicoll@pivotal.io>

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/Packaging.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.packaging;
+
+import java.util.Objects;
+
+import org.springframework.core.io.support.SpringFactoriesLoader;
+
+/**
+ * Application packaging, such as a jar file or a war file.
+ *
+ * @author Andy Wilkinson
+ */
+public interface Packaging {
+
+	String id();
+
+	static Packaging forId(String id) {
+		return SpringFactoriesLoader
+				.loadFactories(PackagingFactory.class, Packaging.class.getClassLoader())
+				.stream().map((factory) -> factory.createPackaging(id))
+				.filter(Objects::nonNull).findFirst()
+				.orElseThrow(() -> new IllegalStateException(
+						"Unrecognized packaging id '" + id + "'"));
+	}
+
+}

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/PackagingFactory.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.packaging;
+
+/**
+ * A factory for creating a {@link Packaging}.
+ *
+ * @author Andy Wilkinson
+ */
+public interface PackagingFactory {
+
+	/**
+	 * Creates and returns a {@link Packaging} for the given id. If the factory does not
+	 * recognise the given {@code id}, {@code null} should be returned.
+	 * @param id the id of the packaging
+	 * @return the packaging or {@code null}
+	 */
+	Packaging createPackaging(String id);
+
+}

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/jar/JarPackaging.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.packaging.jar;
+
+import io.spring.initializr.generator.packaging.Packaging;
+
+/**
+ * Jar {@link Packaging}.
+ *
+ * @author Andy Wilkinson
+ */
+public final class JarPackaging implements Packaging {
+
+	/**
+	 * Jar {@link Packaging} identifier.
+	 */
+	public static final String ID = "jar";
+
+	@Override
+	public String id() {
+		return ID;
+	}
+
+	@Override
+	public String toString() {
+		return id();
+	}
+
+}

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/jar/JarPackagingFactory.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.packaging.jar;
+
+import io.spring.initializr.generator.packaging.Packaging;
+import io.spring.initializr.generator.packaging.PackagingFactory;
+
+/**
+ * {@link PackagingFactory Factory} for {@link JarPackaging}.
+ *
+ * @author Andy Wilkinson
+ */
+class JarPackagingFactory implements PackagingFactory {
+
+	@Override
+	public Packaging createPackaging(String id) {
+		if (JarPackaging.ID.equals(id)) {
+			return new JarPackaging();
+		}
+		return null;
+	}
+
+}

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/jar/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2019 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.
+ */
+
+/**
+ * Java archive packaging.
+ */
+package io.spring.initializr.generator.packaging.jar;

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2019 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.
+ */
+
+/**
+ * Packaging abstraction.
+ */
+package io.spring.initializr.generator.packaging;

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/war/WarPackaging.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.packaging.war;
+
+import io.spring.initializr.generator.packaging.Packaging;
+
+/**
+ * War {@link Packaging}.
+ *
+ * @author Andy Wilkinson
+ */
+public final class WarPackaging implements Packaging {
+
+	/**
+	 * War {@link Packaging} identifier.
+	 */
+	public static final String ID = "war";
+
+	@Override
+	public String id() {
+		return ID;
+	}
+
+	@Override
+	public String toString() {
+		return id();
+	}
+
+}

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/war/WarPackagingFactory.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.packaging.war;
+
+import io.spring.initializr.generator.packaging.Packaging;
+import io.spring.initializr.generator.packaging.PackagingFactory;
+
+/**
+ * {@link PackagingFactory Factory} for {@link WarPackaging}.
+ *
+ * @author Andy Wilkinson
+ */
+class WarPackagingFactory implements PackagingFactory {
+
+	@Override
+	public Packaging createPackaging(String id) {
+		if (WarPackaging.ID.equals(id)) {
+			return new WarPackaging();
+		}
+		return null;
+	}
+
+}

initializr-generator/src/main/java/io/spring/initializr/generator/packaging/war/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-2019 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.
+ */
+
+/**
+ * Web Application archive packaging.
+ */
+package io.spring.initializr.generator.packaging.war;

initializr-generator/src/main/resources/META-INF/spring.factories

@@ -6,3 +6,7 @@ io.spring.initializr.generator.language.LanguageFactory=\
 io.spring.initializr.generator.language.groovy.GroovyLanguageFactory,\
 io.spring.initializr.generator.language.java.JavaLanguageFactory,\
 io.spring.initializr.generator.language.kotlin.KotlinLanguageFactory
+
+io.spring.initializr.generator.packaging.PackagingFactory=\
+io.spring.initializr.generator.packaging.jar.JarPackagingFactory,\
+io.spring.initializr.generator.packaging.war.WarPackagingFactory

initializr-generator/src/test/java/io/spring/initializr/generator/packaging/PackagingTests.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2012-2019 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 io.spring.initializr.generator.packaging;
+
+import io.spring.initializr.generator.packaging.jar.JarPackaging;
+import io.spring.initializr.generator.packaging.war.WarPackaging;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+
+/**
+ * Tests for {@link Packaging}.
+ *
+ * @author Stephane Nicoll
+ */
+class PackagingTests {
+
+	@Test
+	void jarPackaging() {
+		Packaging jar = Packaging.forId("jar");
+		assertThat(jar).isInstanceOf(JarPackaging.class);
+		assertThat(jar.id()).isEqualTo("jar");
+		assertThat(jar.toString()).isEqualTo("jar");
+	}
+
+	@Test
+	void warPackaging() {
+		Packaging war = Packaging.forId("war");
+		assertThat(war).isInstanceOf(WarPackaging.class);
+		assertThat(war.id()).isEqualTo("war");
+		assertThat(war.toString()).isEqualTo("war");
+	}
+
+	@Test
+	void unknownPackaging() {
+		assertThatIllegalStateException().isThrownBy(() -> Packaging.forId("unknown"))
+				.withMessageContaining("Unrecognized packaging id 'unknown'");
+	}
+
+}