Generate auto-configuration OnBean data

Update the auto-configuration annotation processor to generate
properties for `@ConditionalOnBean` and `@ConditionalOnSingleCandidate`.

See gh-13328

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/main/java/org/springframework/boot/autoconfigureprocessor/AutoConfigureAnnotationProcessor.java

@@ -18,14 +18,15 @@ package org.springframework.boot.autoconfigureprocessor;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.Map.Entry;
 import java.util.Properties;
 import java.util.Set;
-import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import javax.annotation.processing.AbstractProcessor;
@@ -36,10 +37,8 @@ import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.AnnotationValue;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ElementKind;
-import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.type.DeclaredType;
-import javax.lang.model.type.TypeMirror;
 import javax.tools.FileObject;
 import javax.tools.StandardLocation;
 
@@ -52,6 +51,8 @@ import javax.tools.StandardLocation;
  */
 @SupportedAnnotationTypes({ "org.springframework.context.annotation.Configuration",
 		"org.springframework.boot.autoconfigure.condition.ConditionalOnClass",
+		"org.springframework.boot.autoconfigure.condition.ConditionalOnBean",
+		"org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandidate",
 		"org.springframework.boot.autoconfigure.AutoConfigureBefore",
 		"org.springframework.boot.autoconfigure.AutoConfigureAfter",
 		"org.springframework.boot.autoconfigure.AutoConfigureOrder" })
@@ -60,7 +61,9 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 	protected static final String PROPERTIES_PATH = "META-INF/"
 			+ "spring-autoconfigure-metadata.properties";
 
-	private Map<String, String> annotations;
+	private final Map<String, String> annotations;
+
+	private final Map<String, ValueExtractor> valueExtractors;
 
 	private final Properties properties = new Properties();
 
@@ -68,6 +71,9 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 		Map<String, String> annotations = new LinkedHashMap<>();
 		addAnnotations(annotations);
 		this.annotations = Collections.unmodifiableMap(annotations);
+		Map<String, ValueExtractor> valueExtractors = new LinkedHashMap<>();
+		addValueExtractors(valueExtractors);
+		this.valueExtractors = Collections.unmodifiableMap(valueExtractors);
 	}
 
 	protected void addAnnotations(Map<String, String> annotations) {
@@ -75,6 +81,10 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 				"org.springframework.context.annotation.Configuration");
 		annotations.put("ConditionalOnClass",
 				"org.springframework.boot.autoconfigure.condition.ConditionalOnClass");
+		annotations.put("ConditionalOnBean",
+				"org.springframework.boot.autoconfigure.condition.ConditionalOnBean");
+		annotations.put("ConditionalOnSingleCandidate",
+				"org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandidate");
 		annotations.put("AutoConfigureBefore",
 				"org.springframework.boot.autoconfigure.AutoConfigureBefore");
 		annotations.put("AutoConfigureAfter",
@@ -83,6 +93,17 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 				"org.springframework.boot.autoconfigure.AutoConfigureOrder");
 	}
 
+	private void addValueExtractors(Map<String, ValueExtractor> attributes) {
+		attributes.put("Configuration", ValueExtractor.allFrom("value"));
+		attributes.put("ConditionalOnClass", ValueExtractor.allFrom("value", "name"));
+		attributes.put("ConditionalOnBean", new OnBeanConditionValueExtractor());
+		attributes.put("ConditionalOnSingleCandidate",
+				new OnBeanConditionValueExtractor());
+		attributes.put("AutoConfigureBefore", ValueExtractor.allFrom("value", "name"));
+		attributes.put("AutoConfigureAfter", ValueExtractor.allFrom("value", "name"));
+		attributes.put("AutoConfigureOrder", ValueExtractor.allFrom("value"));
+	}
+
 	@Override
 	public SourceVersion getSupportedSourceVersion() {
 		return SourceVersion.latestSupported();
@@ -123,10 +144,10 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 	private void processElement(Element element, String propertyKey,
 			String annotationName) {
 		try {
-			String qualifiedName = getQualifiedName(element);
+			String qualifiedName = Elements.getQualifiedName(element);
 			AnnotationMirror annotation = getAnnotation(element, annotationName);
 			if (qualifiedName != null && annotation != null) {
-				List<Object> values = getValues(annotation);
+				List<Object> values = getValues(propertyKey, annotation);
 				this.properties.put(qualifiedName + "." + propertyKey,
 						toCommaDelimitedString(values));
 				this.properties.put(qualifiedName, "");
@@ -158,68 +179,89 @@ public class AutoConfigureAnnotationProcessor extends AbstractProcessor {
 		return result.toString();
 	}
 
-	private List<Object> getValues(AnnotationMirror annotation) {
-		return annotation.getElementValues().entrySet().stream()
-				.filter(this::isNameOrValueAttribute).flatMap(this::getValues)
-				.collect(Collectors.toList());
-	}
-
-	private boolean isNameOrValueAttribute(Entry<? extends ExecutableElement, ?> entry) {
-		String attributeName = entry.getKey().getSimpleName().toString();
-		return "name".equals(attributeName) || "value".equals(attributeName);
+	private List<Object> getValues(String propertyKey, AnnotationMirror annotation) {
+		ValueExtractor extractor = this.valueExtractors.get(propertyKey);
+		if (extractor == null) {
+			return Collections.emptyList();
+		}
+		return extractor.getValues(annotation);
 	}
 
-	@SuppressWarnings("unchecked")
-	private Stream<Object> getValues(Entry<?, ? extends AnnotationValue> entry) {
-		Object value = entry.getValue().getValue();
-		if (value instanceof List) {
-			return ((List<AnnotationValue>) value).stream()
-					.map((annotation) -> processValue(annotation.getValue()));
+	private void writeProperties() throws IOException {
+		if (!this.properties.isEmpty()) {
+			FileObject file = this.processingEnv.getFiler()
+					.createResource(StandardLocation.CLASS_OUTPUT, "", PROPERTIES_PATH);
+			try (OutputStream outputStream = file.openOutputStream()) {
+				this.properties.store(outputStream, null);
+			}
 		}
-		return Stream.of(processValue(value));
 	}
 
-	private Object processValue(Object value) {
-		if (value instanceof DeclaredType) {
-			return getQualifiedName(((DeclaredType) value).asElement());
+	@FunctionalInterface
+	private interface ValueExtractor {
+
+		List<Object> getValues(AnnotationMirror annotation);
+
+		static ValueExtractor allFrom(String... attributes) {
+			Set<String> names = new HashSet<>(Arrays.asList(attributes));
+			return new AbstractValueExtractor() {
+
+				@Override
+				public List<Object> getValues(AnnotationMirror annotation) {
+					List<Object> result = new ArrayList<>();
+					annotation.getElementValues().forEach((key, value) -> {
+						if (names.contains(key.getSimpleName().toString())) {
+							extractValues(value).forEach(result::add);
+						}
+					});
+					return result;
+				}
+
+			};
 		}
-		return value;
+
 	}
 
-	private String getQualifiedName(Element element) {
-		if (element != null) {
-			TypeElement enclosingElement = getEnclosingTypeElement(element.asType());
-			if (enclosingElement != null) {
-				return getQualifiedName(enclosingElement) + "$"
-						+ ((DeclaredType) element.asType()).asElement().getSimpleName()
-								.toString();
+	private abstract static class AbstractValueExtractor implements ValueExtractor {
+
+		@SuppressWarnings("unchecked")
+		protected Stream<Object> extractValues(AnnotationValue annotationValue) {
+			if (annotationValue == null) {
+				return Stream.empty();
 			}
-			if (element instanceof TypeElement) {
-				return ((TypeElement) element).getQualifiedName().toString();
+			Object value = annotationValue.getValue();
+			if (value instanceof List) {
+				return ((List<AnnotationValue>) value).stream()
+						.map((annotation) -> extractValue(annotation.getValue()));
 			}
+			return Stream.of(extractValue(value));
 		}
-		return null;
-	}
 
-	private TypeElement getEnclosingTypeElement(TypeMirror type) {
-		if (type instanceof DeclaredType) {
-			DeclaredType declaredType = (DeclaredType) type;
-			Element enclosingElement = declaredType.asElement().getEnclosingElement();
-			if (enclosingElement != null && enclosingElement instanceof TypeElement) {
-				return (TypeElement) enclosingElement;
+		private Object extractValue(Object value) {
+			if (value instanceof DeclaredType) {
+				return Elements.getQualifiedName(((DeclaredType) value).asElement());
 			}
+			return value;
 		}
-		return null;
+
 	}
 
-	private void writeProperties() throws IOException {
-		if (!this.properties.isEmpty()) {
-			FileObject file = this.processingEnv.getFiler()
-					.createResource(StandardLocation.CLASS_OUTPUT, "", PROPERTIES_PATH);
-			try (OutputStream outputStream = file.openOutputStream()) {
-				this.properties.store(outputStream, null);
+	private static class OnBeanConditionValueExtractor extends AbstractValueExtractor {
+
+		@Override
+		public List<Object> getValues(AnnotationMirror annotation) {
+			Map<String, AnnotationValue> attributes = new LinkedHashMap<>();
+			annotation.getElementValues().forEach((key, value) -> attributes
+					.put(key.getSimpleName().toString(), value));
+			if (attributes.containsKey("name")) {
+				return Collections.emptyList();
 			}
+			List<Object> result = new ArrayList<>();
+			extractValues(attributes.get("value")).forEach(result::add);
+			extractValues(attributes.get("type")).forEach(result::add);
+			return result;
 		}
+
 	}
 
 }

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/main/java/org/springframework/boot/autoconfigureprocessor/Elements.java

@@ -0,0 +1,60 @@
+/*
+ * Copyright 2012-2018 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.autoconfigureprocessor;
+
+import javax.lang.model.element.Element;
+import javax.lang.model.element.TypeElement;
+import javax.lang.model.type.DeclaredType;
+import javax.lang.model.type.TypeMirror;
+
+/**
+ * Utilities for dealing with {@link Element} classes.
+ *
+ * @author Phillip Webb
+ */
+final class Elements {
+
+	private Elements() {
+	}
+
+	static String getQualifiedName(Element element) {
+		if (element != null) {
+			TypeElement enclosingElement = getEnclosingTypeElement(element.asType());
+			if (enclosingElement != null) {
+				return getQualifiedName(enclosingElement) + "$"
+						+ ((DeclaredType) element.asType()).asElement().getSimpleName()
+								.toString();
+			}
+			if (element instanceof TypeElement) {
+				return ((TypeElement) element).getQualifiedName().toString();
+			}
+		}
+		return null;
+	}
+
+	private static TypeElement getEnclosingTypeElement(TypeMirror type) {
+		if (type instanceof DeclaredType) {
+			DeclaredType declaredType = (DeclaredType) type;
+			Element enclosingElement = declaredType.asElement().getEnclosingElement();
+			if (enclosingElement != null && enclosingElement instanceof TypeElement) {
+				return (TypeElement) enclosingElement;
+			}
+		}
+		return null;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/test/java/org/springframework/boot/autoconfigureprocessor/AutoConfigureAnnotationProcessorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -50,18 +50,38 @@ public class AutoConfigureAnnotationProcessorTests {
 	@Test
 	public void annotatedClass() throws Exception {
 		Properties properties = compile(TestClassConfiguration.class);
-		assertThat(properties).hasSize(3);
+		assertThat(properties).hasSize(5);
 		assertThat(properties).containsEntry(
 				"org.springframework.boot.autoconfigureprocessor."
 						+ "TestClassConfiguration.ConditionalOnClass",
 				"java.io.InputStream,org.springframework.boot.autoconfigureprocessor."
 						+ "TestClassConfiguration$Nested");
-		assertThat(properties).containsKey(
-				"org.springframework.boot.autoconfigureprocessor.TestClassConfiguration");
-		assertThat(properties).containsKey(
-				"org.springframework.boot.autoconfigureprocessor.TestClassConfiguration.Configuration");
-		assertThat(properties).doesNotContainKey(
-				"org.springframework.boot.autoconfigureprocessor.TestClassConfiguration$Nested");
+		assertThat(properties)
+				.containsKey("org.springframework.boot.autoconfigureprocessor."
+						+ "TestClassConfiguration");
+		assertThat(properties)
+				.containsKey("org.springframework.boot.autoconfigureprocessor."
+						+ "TestClassConfiguration.Configuration");
+		assertThat(properties)
+				.doesNotContainKey("org.springframework.boot.autoconfigureprocessor."
+						+ "TestClassConfiguration$Nested");
+		assertThat(properties).containsEntry(
+				"org.springframework.boot.autoconfigureprocessor."
+						+ "TestClassConfiguration.ConditionalOnBean",
+				"java.io.OutputStream");
+		assertThat(properties).containsEntry(
+				"org.springframework.boot.autoconfigureprocessor."
+						+ "TestClassConfiguration.ConditionalOnSingleCandidate",
+				"java.io.OutputStream");
+	}
+
+	@Test
+	public void annoatedClassWithOnBeanThatHasName() throws Exception {
+		Properties properties = compile(TestOnBeanWithNameClassConfiguration.class);
+		assertThat(properties).hasSize(3);
+		assertThat(properties).containsEntry(
+				"org.springframework.boot.autoconfigureprocessor.TestOnBeanWithNameClassConfiguration.ConditionalOnBean",
+				"");
 	}
 
 	@Test

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/test/java/org/springframework/boot/autoconfigureprocessor/TestClassConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -23,6 +23,8 @@ package org.springframework.boot.autoconfigureprocessor;
  */
 @TestConfiguration
 @TestConditionalOnClass(name = "java.io.InputStream", value = TestClassConfiguration.Nested.class)
+@TestConditionalOnBean(type = "java.io.OutputStream")
+@TestConditionalOnSingleCandidate(type = "java.io.OutputStream")
 public class TestClassConfiguration {
 
 	@TestAutoConfigureOrder

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/test/java/org/springframework/boot/autoconfigureprocessor/TestConditionMetadataAnnotationProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2018 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.
@@ -32,6 +32,8 @@ import javax.annotation.processing.SupportedAnnotationTypes;
 @SupportedAnnotationTypes({
 		"org.springframework.boot.autoconfigureprocessor.TestConfiguration",
 		"org.springframework.boot.autoconfigureprocessor.TestConditionalOnClass",
+		"org.springframework.boot.autoconfigure.condition.TestConditionalOnBean",
+		"org.springframework.boot.autoconfigure.condition.TestConditionalOnSingleCandidate",
 		"org.springframework.boot.autoconfigureprocessor.TestAutoConfigureBefore",
 		"org.springframework.boot.autoconfigureprocessor.TestAutoConfigureAfter",
 		"org.springframework.boot.autoconfigureprocessor.TestAutoConfigureOrder" })
@@ -48,6 +50,9 @@ public class TestConditionMetadataAnnotationProcessor
 	protected void addAnnotations(Map<String, String> annotations) {
 		put(annotations, "Configuration", TestConfiguration.class);
 		put(annotations, "ConditionalOnClass", TestConditionalOnClass.class);
+		put(annotations, "ConditionalOnBean", TestConditionalOnBean.class);
+		put(annotations, "ConditionalOnSingleCandidate",
+				TestConditionalOnSingleCandidate.class);
 		put(annotations, "AutoConfigureBefore", TestAutoConfigureBefore.class);
 		put(annotations, "AutoConfigureAfter", TestAutoConfigureAfter.class);
 		put(annotations, "AutoConfigureOrder", TestAutoConfigureOrder.class);

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/test/java/org/springframework/boot/autoconfigureprocessor/TestConditionalOnBean.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2012-2018 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.autoconfigureprocessor;
+
+import java.lang.annotation.Annotation;
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Alternative to Spring Boot's {@code ConditionalOnBean} for testing (removes the need
+ * for a dependency on the real annotation).
+ *
+ * @author Phillip Webb
+ */
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface TestConditionalOnBean {
+
+	Class<?>[] value() default {};
+
+	String[] type() default {};
+
+	Class<? extends Annotation>[] annotation() default {};
+
+	String[] name() default {};
+
+}

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/test/java/org/springframework/boot/autoconfigureprocessor/TestConditionalOnSingleCandidate.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2012-2018 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.autoconfigureprocessor;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Alternative to Spring Boot's {@code ConditionalOnSingleCandidate} for testing (removes
+ * the need for a dependency on the real annotation).
+ *
+ * @author Phillip Webb
+ */
+@Target({ ElementType.TYPE, ElementType.METHOD })
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+public @interface TestConditionalOnSingleCandidate {
+
+	Class<?> value() default Object.class;
+
+	String type() default "";
+
+}

spring-boot-project/spring-boot-tools/spring-boot-autoconfigure-processor/src/test/java/org/springframework/boot/autoconfigureprocessor/TestOnBeanWithNameClassConfiguration.java

@@ -0,0 +1,28 @@
+/*
+ * Copyright 2012-2018 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.autoconfigureprocessor;
+
+/**
+ * Test configuration with an annotated class.
+ *
+ * @author Phillip Webb
+ */
+@TestConfiguration
+@TestConditionalOnBean(name = "test", type = "java.io.OutputStream")
+public class TestOnBeanWithNameClassConfiguration {
+
+}