Add exclusion for well-known property types

Previously, any valid property was added to the meta-data of the current
group. This can be annoying for types that are not meant to be bound from
a simple string value. ClassLoader is one example.

A list of well-known types has been added: if the property type matches
an element of this list, it is ignored.

Fixes gh-2012

spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessor.java

@@ -75,6 +75,8 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 
 	private FieldValuesParser fieldValuesParser;
 
+	private ElementExcludeFilter elementExcludeFilter = new ElementExcludeFilter();
+
 	protected String configurationPropertiesAnnotation() {
 		return CONFIGURATION_PROPERTIES_ANNOTATION;
 	}
@@ -177,10 +179,11 @@ public class ConfigurationMetadataAnnotationProcessor extends AbstractProcessor
 			VariableElement field = members.getFields().get(name);
 			Element returnType = this.processingEnv.getTypeUtils().asElement(
 					getter.getReturnType());
+			boolean isExcluded = this.elementExcludeFilter.isExcluded(returnType);
 			boolean isNested = isNested(returnType, field, element);
 			boolean isCollection = this.typeUtils.isCollectionOrMap(getter
 					.getReturnType());
-			if (!isNested && (setter != null || isCollection)) {
+			if (!isExcluded && !isNested && (setter != null || isCollection)) {
 				String dataType = this.typeUtils.getType(getter.getReturnType());
 				String sourceType = this.typeUtils.getType(element);
 				String description = this.typeUtils.getJavaDoc(field);

spring-boot-tools/spring-boot-configuration-processor/src/main/java/org/springframework/boot/configurationprocessor/TypeElementFilter.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2012-2014 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.configurationprocessor;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import javax.lang.model.element.Element;
+
+/**
+ * Filter to excluded elements that don't make sense to process.
+ *
+ * @author Stephane Nicoll
+ * @since 1.2.0
+ */
+class ElementExcludeFilter {
+
+	private final Set<String> excludes = new HashSet<String>();
+
+	public ElementExcludeFilter() {
+		add("java.io.Writer");
+		add("java.io.PrintWriter");
+		add("javax.sql.DataSource");
+		add("java.lang.ClassLoader");
+	}
+
+	private void add(String className) {
+		this.excludes.add(className);
+	}
+
+	public boolean isExcluded(Element element) {
+		if (element == null) {
+			return false;
+		}
+		return this.excludes.contains(element.toString());
+	}
+
+}

spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationprocessor/ConfigurationMetadataAnnotationProcessorTests.java

@@ -30,7 +30,6 @@ import org.springframework.boot.configurationsample.method.EmptyTypeMethodConfig
 import org.springframework.boot.configurationsample.method.InvalidMethodConfig;
 import org.springframework.boot.configurationsample.method.MethodAndClassConfig;
 import org.springframework.boot.configurationsample.method.SimpleMethodConfig;
-import org.springframework.boot.configurationsample.simple.DeprecatedProperties;
 import org.springframework.boot.configurationsample.simple.HierarchicalProperties;
 import org.springframework.boot.configurationsample.simple.NotAnnotated;
 import org.springframework.boot.configurationsample.simple.SimpleCollectionProperties;
@@ -38,6 +37,7 @@ import org.springframework.boot.configurationsample.simple.SimplePrefixValueProp
 import org.springframework.boot.configurationsample.simple.SimpleProperties;
 import org.springframework.boot.configurationsample.simple.SimpleTypeProperties;
 import org.springframework.boot.configurationsample.specific.BuilderPojo;
+import org.springframework.boot.configurationsample.specific.ExcludedTypesPojo;
 import org.springframework.boot.configurationsample.specific.InnerClassAnnotatedGetterConfig;
 import org.springframework.boot.configurationsample.specific.InnerClassProperties;
 import org.springframework.boot.configurationsample.specific.InnerClassRootConfig;
@@ -145,21 +145,16 @@ public class ConfigurationMetadataAnnotationProcessorTests {
 				.fromSource(HierarchicalProperties.class));
 	}
 
-	@SuppressWarnings("deprecation")
 	@Test
+	@SuppressWarnings("deprecation")
 	public void deprecatedProperties() throws Exception {
-		ConfigurationMetadata metadata = compile(DeprecatedProperties.class);
-		assertThat(metadata, containsGroup("deprecated").fromSource(DeprecatedProperties.class));
-		assertThat(
-				metadata,
-				containsProperty("deprecated.name", String.class)
-						.fromSource(DeprecatedProperties.class)
-						.withDeprecated());
-		assertThat(
-				metadata,
-				containsProperty("deprecated.description", String.class)
-						.fromSource(DeprecatedProperties.class)
-						.withDeprecated());
+		Class<?> type = org.springframework.boot.configurationsample.simple.DeprecatedProperties.class;
+		ConfigurationMetadata metadata = compile(type);
+		assertThat(metadata, containsGroup("deprecated").fromSource(type));
+		assertThat(metadata, containsProperty("deprecated.name", String.class)
+				.fromSource(type).withDeprecated());
+		assertThat(metadata, containsProperty("deprecated.description", String.class)
+				.fromSource(type).withDeprecated());
 	}
 
 	@Test
@@ -279,6 +274,16 @@ public class ConfigurationMetadataAnnotationProcessorTests {
 		assertThat(metadata, containsProperty("builder.name"));
 	}
 
+	@Test
+	public void excludedTypesPojo() throws IOException {
+		ConfigurationMetadata metadata = compile(ExcludedTypesPojo.class);
+		assertThat(metadata, containsProperty("excluded.name"));
+		assertThat(metadata, not(containsProperty("excluded.class-loader")));
+		assertThat(metadata, not(containsProperty("excluded.data-source")));
+		assertThat(metadata, not(containsProperty("excluded.print-writer")));
+		assertThat(metadata, not(containsProperty("excluded.writer")));
+	}
+
 	private ConfigurationMetadata compile(Class<?>... types) throws IOException {
 		TestConfigurationMetadataAnnotationProcessor processor = new TestConfigurationMetadataAnnotationProcessor();
 		new TestCompiler(this.temporaryFolder).getTask(types).call(processor);

spring-boot-tools/spring-boot-configuration-processor/src/test/java/org/springframework/boot/configurationsample/specific/ExcludedTypesPojo.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2012-2014 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.configurationsample.specific;
+
+import java.io.PrintWriter;
+import java.io.Writer;
+
+import javax.sql.DataSource;
+
+import org.springframework.boot.configurationsample.ConfigurationProperties;
+
+/**
+ * Sample config with types that should not be added to the meta-data as we have no way to
+ * bind them from simple strings.
+ *
+ * @author Stephane Nicoll
+ */
+@ConfigurationProperties(prefix = "excluded")
+public class ExcludedTypesPojo {
+
+	private String name;
+
+	private ClassLoader classLoader;
+
+	private DataSource dataSource;
+
+	private PrintWriter printWriter;
+
+	private Writer writer;
+
+	public String getName() {
+		return this.name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	public ClassLoader getClassLoader() {
+		return this.classLoader;
+	}
+
+	public void setClassLoader(ClassLoader classLoader) {
+		this.classLoader = classLoader;
+	}
+
+	public DataSource getDataSource() {
+		return this.dataSource;
+	}
+
+	public void setDataSource(DataSource dataSource) {
+		this.dataSource = dataSource;
+	}
+
+	public PrintWriter getPrintWriter() {
+		return this.printWriter;
+	}
+
+	public void setPrintWriter(PrintWriter printWriter) {
+		this.printWriter = printWriter;
+	}
+
+	public Writer getWriter() {
+		return this.writer;
+	}
+
+	public void setWriter(Writer writer) {
+		this.writer = writer;
+	}
+
+}