Merge pull request #9443 from tsachev:gh-9442

* pr/9443:
  Polish
  Polish "Allow abstract serializers/deserializer in @JsonComponent"
  Allow abstract serializers/deserializer in @JsonComponent

Author: snicoll

spring-boot/src/main/java/org/springframework/boot/jackson/JsonComponentModule.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -16,6 +16,7 @@
 
 package org.springframework.boot.jackson;
 
+import java.lang.reflect.Modifier;
 import java.util.Map;
 
 import javax.annotation.PostConstruct;
@@ -78,8 +79,9 @@ private void addJsonBean(Object bean) {
 			addDeserializerWithDeducedType((JsonDeserializer<?>) bean);
 		}
 		for (Class<?> innerClass : bean.getClass().getDeclaredClasses()) {
-			if (JsonSerializer.class.isAssignableFrom(innerClass)
-					|| JsonDeserializer.class.isAssignableFrom(innerClass)) {
+			if (!Modifier.isAbstract(innerClass.getModifiers()) &&
+					(JsonSerializer.class.isAssignableFrom(innerClass)
+							|| JsonDeserializer.class.isAssignableFrom(innerClass))) {
 				try {
 					addJsonBean(innerClass.newInstance());
 				}

spring-boot/src/test/java/org/springframework/boot/jackson/JsonComponentModuleTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -18,6 +18,7 @@
 
 import com.fasterxml.jackson.databind.Module;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.After;
 import org.junit.Test;
 
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
@@ -31,34 +32,54 @@
  */
 public class JsonComponentModuleTests {
 
+	private AnnotationConfigApplicationContext context;
+
+	@After
+	public void closeContext() {
+		if (this.context != null) {
+			this.context.close();
+		}
+	}
+
 	@Test
 	public void moduleShouldRegisterSerializers() throws Exception {
-		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
-				JsonComponentModule.class, OnlySerializer.class);
-		JsonComponentModule module = context.getBean(JsonComponentModule.class);
+		load(OnlySerializer.class);
+		JsonComponentModule module = this.context.getBean(JsonComponentModule.class);
 		assertSerialize(module);
-		context.close();
 	}
 
 	@Test
 	public void moduleShouldRegisterDeserializers() throws Exception {
-		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
-				JsonComponentModule.class, OnlyDeserializer.class);
-		JsonComponentModule module = context.getBean(JsonComponentModule.class);
+		load(OnlyDeserializer.class);
+		JsonComponentModule module = this.context.getBean(JsonComponentModule.class);
 		assertDeserialize(module);
-		context.close();
 	}
 
 	@Test
 	public void moduleShouldRegisterInnerClasses() throws Exception {
+		load(NameAndAgeJsonComponent.class);
+		JsonComponentModule module = this.context.getBean(JsonComponentModule.class);
+		assertSerialize(module);
+		assertDeserialize(module);
+	}
+
+	@Test
+	public void moduleShouldAllowInnerAbstractClasses() throws Exception {
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(
-				JsonComponentModule.class, NameAndAgeJsonComponent.class);
+				JsonComponentModule.class, ComponentWithInnerAbstractClass.class);
 		JsonComponentModule module = context.getBean(JsonComponentModule.class);
 		assertSerialize(module);
-		assertDeserialize(module);
 		context.close();
 	}
 
+	private void load(Class<?>... configs) {
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
+		ctx.register(configs);
+		ctx.register(JsonComponentModule.class);
+		ctx.refresh();
+		this.context = ctx;
+	}
+
 	private void assertSerialize(Module module) throws Exception {
 		ObjectMapper mapper = new ObjectMapper();
 		mapper.registerModule(module);
@@ -85,4 +106,15 @@ static class OnlyDeserializer extends NameAndAgeJsonComponent.Deserializer {
 
 	}
 
+	@JsonComponent
+	static class ComponentWithInnerAbstractClass {
+
+		private static abstract class AbstractSerializer extends NameAndAgeJsonComponent.Serializer {
+
+		}
+
+		static class ConcreteSerializer extends AbstractSerializer {
+
+		}
+	}
 }