Add support for customizing layers in Maven

This commit adds an additional 'layers/configuration' property that can
be used to refer to a separate layers configuration file. This separate
file defines:

* The layers and their order of precedence,
* How libraries are handled using filters that match against the
coordinates of each library, and
* How classes are handled using filters that match against the location
of the entry

An XSD to validate the XML configuration file is available.

Closes gh-20295

Co-authored-by: Stephane Nicoll <[email protected]>

Author: mbhave

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

@@ -25,6 +25,7 @@
  * Encapsulates information about a single library that may be packed into the archive.
  *
  * @author Phillip Webb
+ * @author Scott Frederick
  * @since 1.1.2
  * @see Libraries
  */
@@ -38,6 +39,8 @@ public class Library {
 
 	private final boolean unpackRequired;
 
+	private final LibraryCoordinates coordinates;
+
 	/**
 	 * Create a new {@link Library}.
 	 * @param file the source file
@@ -66,10 +69,15 @@ public Library(File file, LibraryScope scope, boolean unpackRequired) {
 	 * @param unpackRequired if the library needs to be unpacked before it can be used
 	 */
 	public Library(String name, File file, LibraryScope scope, boolean unpackRequired) {
+		this(name, file, scope, unpackRequired, null);
+	}
+
+	public Library(String name, File file, LibraryScope scope, boolean unpackRequired, LibraryCoordinates coordinates) {
 		this.name = (name != null) ? name : file.getName();
 		this.file = file;
 		this.scope = scope;
 		this.unpackRequired = unpackRequired;
+		this.coordinates = coordinates;
 	}
 
 	/**
@@ -114,6 +122,14 @@ public boolean isUnpackRequired() {
 		return this.unpackRequired;
 	}
 
+	/**
+	 * Return the {@linkplain LibraryCoordinates coordinates} of the library.
+	 * @return the coordinates
+	 */
+	public LibraryCoordinates getCoordinates() {
+		return this.coordinates;
+	}
+
 	long getLastModified() {
 		return this.file.lastModified();
 	}

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

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2012-2020 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.boot.loader.tools;
+
+import org.springframework.util.Assert;
+
+/**
+ * Encapsulates information about the Maven artifact coordinates of a library.
+ *
+ * @author Scott Frederick
+ * @since 2.3.0
+ */
+public final class LibraryCoordinates {
+
+	private final String groupId;
+
+	private final String artifactId;
+
+	private final String version;
+
+	/**
+	 * Create a new instance from discrete elements.
+	 * @param groupId the group ID
+	 * @param artifactId the artifact ID
+	 * @param version the version
+	 */
+	public LibraryCoordinates(String groupId, String artifactId, String version) {
+		this.groupId = groupId;
+		this.artifactId = artifactId;
+		this.version = version;
+	}
+
+	/**
+	 * Create a new instance from a String value in the form
+	 * {@code groupId:artifactId:version} where the version is optional.
+	 * @param coordinates the coordinates
+	 */
+	public LibraryCoordinates(String coordinates) {
+		String[] elements = coordinates.split(":");
+		Assert.isTrue(elements.length >= 2, "Coordinates must contain at least 'groupId:artifactId'");
+		this.groupId = elements[0];
+		this.artifactId = elements[1];
+		if (elements.length > 2) {
+			this.version = elements[2];
+		}
+		else {
+			this.version = null;
+		}
+	}
+
+	public String getGroupId() {
+		return this.groupId;
+	}
+
+	public String getArtifactId() {
+		return this.artifactId;
+	}
+
+	public String getVersion() {
+		return this.version;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/layer/CustomLayers.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright 2012-2020 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.boot.loader.tools.layer;
+
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+
+import org.springframework.boot.loader.tools.Layer;
+import org.springframework.boot.loader.tools.Layers;
+import org.springframework.boot.loader.tools.Library;
+import org.springframework.boot.loader.tools.layer.classes.ResourceStrategy;
+import org.springframework.boot.loader.tools.layer.library.LibraryStrategy;
+
+/**
+ * Implementation of {@link Layers} representing user-provided layers.
+ *
+ * @author Madhura Bhave
+ * @since 2.3.0
+ */
+public class CustomLayers implements Layers {
+
+	private final List<Layer> layers;
+
+	private final List<ResourceStrategy> resourceStrategies;
+
+	private final List<LibraryStrategy> libraryStrategies;
+
+	public CustomLayers(List<Layer> layers, List<ResourceStrategy> resourceStrategies,
+			List<LibraryStrategy> libraryStrategies) {
+		this.layers = new ArrayList<>(layers);
+		this.resourceStrategies = new ArrayList<>(resourceStrategies);
+		this.libraryStrategies = new ArrayList<>(libraryStrategies);
+	}
+
+	@Override
+	public Iterator<Layer> iterator() {
+		return this.layers.iterator();
+	}
+
+	@Override
+	public Layer getLayer(String resourceName) {
+		for (ResourceStrategy strategy : this.resourceStrategies) {
+			Layer matchingLayer = strategy.getMatchingLayer(resourceName);
+			if (matchingLayer != null) {
+				return matchingLayer;
+			}
+		}
+		throw new IllegalStateException("Resource '" + resourceName + "' did not match any layer.");
+	}
+
+	@Override
+	public Layer getLayer(Library library) {
+		for (LibraryStrategy strategy : this.libraryStrategies) {
+			Layer matchingLayer = strategy.getMatchingLayer(library);
+			if (matchingLayer != null) {
+				return matchingLayer;
+			}
+		}
+		throw new IllegalStateException("Library '" + library.getName() + "' did not match any layer.");
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/layer/classes/AbstractResourceFilter.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2012-2020 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.boot.loader.tools.layer.classes;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * Abstract base class for {@link ResourceFilter} implementations.
+ *
+ * @author Madhura Bhave
+ * @since 2.3.0
+ */
+public abstract class AbstractResourceFilter implements ResourceFilter {
+
+	private final List<String> includes = new ArrayList<>();
+
+	private final List<String> excludes = new ArrayList<>();
+
+	public AbstractResourceFilter(List<String> includes, List<String> excludes) {
+		this.includes.addAll(includes);
+		this.excludes.addAll(excludes);
+	}
+
+	@Override
+	public boolean isResourceIncluded(String resourceName) {
+		return isMatch(resourceName, this.includes);
+	}
+
+	@Override
+	public boolean isResourceExcluded(String resourceName) {
+		return isMatch(resourceName, this.excludes);
+	}
+
+	protected abstract boolean isMatch(String resourceName, List<String> toMatch);
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/layer/classes/FilteredResourceStrategy.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2012-2020 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.boot.loader.tools.layer.classes;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.boot.loader.tools.Layer;
+import org.springframework.util.Assert;
+
+/**
+ * A {@link ResourceStrategy} with custom filters.
+ *
+ * @author Madhura Bhave
+ * @since 2.3.0
+ */
+public class FilteredResourceStrategy implements ResourceStrategy {
+
+	private final Layer layer;
+
+	private final List<ResourceFilter> filters = new ArrayList<>();
+
+	public FilteredResourceStrategy(String layer, List<ResourceFilter> filters) {
+		Assert.notEmpty(filters, "Filters should not be empty for custom strategy.");
+		this.layer = new Layer(layer);
+		this.filters.addAll(filters);
+	}
+
+	public Layer getLayer() {
+		return this.layer;
+	}
+
+	@Override
+	public Layer getMatchingLayer(String resourceName) {
+		boolean isIncluded = false;
+		for (ResourceFilter filter : this.filters) {
+			if (filter.isResourceExcluded(resourceName)) {
+				return null;
+			}
+			if (!isIncluded && filter.isResourceIncluded(resourceName)) {
+				isIncluded = true;
+			}
+		}
+		return (isIncluded) ? this.layer : null;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/layer/classes/LocationFilter.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2012-2020 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.boot.loader.tools.layer.classes;
+
+import java.util.List;
+
+import org.springframework.util.AntPathMatcher;
+
+/**
+ * An implementation of {@link ResourceFilter} based on the resource location.
+ *
+ * @author Madhura Bhave
+ * @since 2.3.0
+ */
+public class LocationFilter extends AbstractResourceFilter {
+
+	private static final AntPathMatcher MATCHER = new AntPathMatcher();
+
+	public LocationFilter(List<String> includes, List<String> excludes) {
+		super(includes, excludes);
+	}
+
+	@Override
+	protected boolean isMatch(String resourceName, List<String> toMatch) {
+		return toMatch.stream().anyMatch((pattern) -> MATCHER.match(pattern, resourceName));
+	}
+
+}