Merge pull request #5803 from Grzegorz Poznachowski

* gh-5803:
  Apply standard Jackson2ObjectMapperBuilder config via a customizer
  Make it easier to customize auto-configured Jackson2ObjectMapperBuilder

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jackson/Jackson2ObjectMapperBuilderCustomizer.java

+/*
+ * Copyright 2012-2016 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.autoconfigure.jackson;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
+
+/**
+ * Callback interface that can be implemented by beans wishing to further customize the
+ * {@link ObjectMapper} via {@link Jackson2ObjectMapperBuilder} retaining its default
+ * auto-configuration.
+ *
+ * @author Grzegorz Poznachowski
+ * @since 1.4.0
+ */
+public interface Jackson2ObjectMapperBuilderCustomizer {
+
+	/**
+	 * Customize the jacksonObjectMapperBuilder.
+	 * @param jacksonObjectMapperBuilder the jacksonObjectMapperBuilder to customize
+	 */
+	void customize(Jackson2ObjectMapperBuilder jacksonObjectMapperBuilder);
+}

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jackson/JacksonAutoConfiguration.java

@@ -20,6 +20,7 @@ import java.lang.reflect.Field;
 import java.text.DateFormat;
 import java.text.SimpleDateFormat;
 import java.util.Collection;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -51,6 +52,7 @@ import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
+import org.springframework.core.Ordered;
 import org.springframework.http.converter.json.Jackson2ObjectMapperBuilder;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -160,24 +162,70 @@ public class JacksonAutoConfiguration {
 
 	@Configuration
 	@ConditionalOnClass({ ObjectMapper.class, Jackson2ObjectMapperBuilder.class })
-	@EnableConfigurationProperties(JacksonProperties.class)
 	static class JacksonObjectMapperBuilderConfiguration {
 
 		private final ApplicationContext applicationContext;
 
-		private final JacksonProperties jacksonProperties;
-
 		JacksonObjectMapperBuilderConfiguration(ApplicationContext applicationContext,
-				JacksonProperties jacksonProperties) {
+				JacksonProperties jacksonProperties,
+				List<Jackson2ObjectMapperBuilderCustomizer> customizers) {
 			this.applicationContext = applicationContext;
-			this.jacksonProperties = jacksonProperties;
 		}
 
 		@Bean
 		@ConditionalOnMissingBean(Jackson2ObjectMapperBuilder.class)
-		public Jackson2ObjectMapperBuilder jacksonObjectMapperBuilder() {
+		public Jackson2ObjectMapperBuilder jacksonObjectMapperBuilder(
+				List<Jackson2ObjectMapperBuilderCustomizer> customizers) {
 			Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
 			builder.applicationContext(this.applicationContext);
+			customize(builder, customizers);
+			return builder;
+		}
+
+		private void customize(Jackson2ObjectMapperBuilder builder,
+				List<Jackson2ObjectMapperBuilderCustomizer> customizers) {
+			for (Jackson2ObjectMapperBuilderCustomizer customizer : customizers) {
+				customizer.customize(builder);
+			}
+		}
+
+	}
+
+	@Configuration
+	@ConditionalOnClass({ ObjectMapper.class, Jackson2ObjectMapperBuilder.class })
+	@EnableConfigurationProperties(JacksonProperties.class)
+	static class Jackson2ObjectMapperBuilderCustomizerConfiguration {
+
+		@Bean
+		public StandardJackson2ObjectMapperBuilderCustomizer standardJacksonObjectMapperBuilderCustomizer(
+				ApplicationContext applicationContext,
+				JacksonProperties jacksonProperties) {
+			return new StandardJackson2ObjectMapperBuilderCustomizer(applicationContext,
+					jacksonProperties);
+		}
+
+		private static final class StandardJackson2ObjectMapperBuilderCustomizer
+				implements Jackson2ObjectMapperBuilderCustomizer, Ordered {
+
+			private final ApplicationContext applicationContext;
+
+			private final JacksonProperties jacksonProperties;
+
+			StandardJackson2ObjectMapperBuilderCustomizer(
+					ApplicationContext applicationContext,
+					JacksonProperties jacksonProperties) {
+				this.applicationContext = applicationContext;
+				this.jacksonProperties = jacksonProperties;
+			}
+
+			@Override
+			public int getOrder() {
+				return 0;
+			}
+
+			@Override
+			public void customize(Jackson2ObjectMapperBuilder builder) {
+
 				if (this.jacksonProperties.getDefaultPropertyInclusion() != null) {
 					builder.serializationInclusion(
 							this.jacksonProperties.getDefaultPropertyInclusion());
@@ -194,7 +242,6 @@ public class JacksonAutoConfiguration {
 				configurePropertyNamingStrategy(builder);
 				configureModules(builder);
 				configureLocale(builder);
-			return builder;
 			}
 
 			private void configureFeatures(Jackson2ObjectMapperBuilder builder,
@@ -220,9 +267,11 @@ public class JacksonAutoConfiguration {
 								(DateFormat) BeanUtils.instantiateClass(dateFormatClass));
 					}
 					catch (ClassNotFoundException ex) {
-					SimpleDateFormat simpleDateFormat = new SimpleDateFormat(dateFormat);
-					// Since Jackson 2.6.3 we always need to set a TimeZone (see gh-4170)
-					// If none in our properties fallback to the Jackson's default
+						SimpleDateFormat simpleDateFormat = new SimpleDateFormat(
+								dateFormat);
+						// Since Jackson 2.6.3 we always need to set a TimeZone (see
+						// gh-4170). If none in our properties fallback to the Jackson's
+						// default
 						TimeZone timeZone = this.jacksonProperties.getTimeZone();
 						if (timeZone == null) {
 							timeZone = new ObjectMapper().getSerializationConfig()
@@ -238,7 +287,8 @@ public class JacksonAutoConfiguration {
 					Jackson2ObjectMapperBuilder builder) {
 				// We support a fully qualified class name extending Jackson's
 				// PropertyNamingStrategy or a string value corresponding to the constant
-			// names in PropertyNamingStrategy which hold default provided implementations
+				// names in PropertyNamingStrategy which hold default provided
+				// implementations
 				String strategy = this.jacksonProperties.getPropertyNamingStrategy();
 				if (strategy != null) {
 					try {
@@ -267,7 +317,8 @@ public class JacksonAutoConfiguration {
 				Assert.notNull(field, "Constant named '" + fieldName + "' not found on "
 						+ PropertyNamingStrategy.class.getName());
 				try {
-				builder.propertyNamingStrategy((PropertyNamingStrategy) field.get(null));
+					builder.propertyNamingStrategy(
+							(PropertyNamingStrategy) field.get(null));
 				}
 				catch (Exception ex) {
 					throw new IllegalStateException(ex);
@@ -277,7 +328,8 @@ public class JacksonAutoConfiguration {
 			private void configureModules(Jackson2ObjectMapperBuilder builder) {
 				Collection<Module> moduleBeans = getBeans(this.applicationContext,
 						Module.class);
-			builder.modulesToInstall(moduleBeans.toArray(new Module[moduleBeans.size()]));
+				builder.modulesToInstall(
+						moduleBeans.toArray(new Module[moduleBeans.size()]));
 			}
 
 			private void configureLocale(Jackson2ObjectMapperBuilder builder) {
@@ -295,4 +347,6 @@ public class JacksonAutoConfiguration {
 
 		}
 
+	}
+
 }

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/jackson/JacksonAutoConfigurationTests.java

@@ -72,6 +72,7 @@ import static org.mockito.Mockito.mock;
  * @author Marcel Overdijk
  * @author Sebastien Deleuze
  * @author Johannes Edmeier
+ * @author Grzegorz Poznachowski
  */
 public class JacksonAutoConfigurationTests {
 
@@ -419,6 +420,15 @@ public class JacksonAutoConfigurationTests {
 				.isEqualTo("\"Koordinierte Universalzeit\"");
 	}
 
+	@Test
+	public void additionalJacksonBuilderCustomization() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class,
+				ObjectMapperBuilderCustomConfig.class);
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertThat(mapper.getDateFormat()).isInstanceOf(MyDateFormat.class);
+	}
+
 	@Test
 	public void parameterNamesModuleIsAutoConfigured() {
 		assertParameterNamesModuleCreatorBinding(Mode.DEFAULT,
@@ -510,6 +520,22 @@ public class JacksonAutoConfigurationTests {
 
 	}
 
+	@Configuration
+	protected static class ObjectMapperBuilderCustomConfig {
+
+		@Bean
+		public Jackson2ObjectMapperBuilderCustomizer customDateFormat() {
+			return new Jackson2ObjectMapperBuilderCustomizer() {
+				@Override
+				public void customize(
+						Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder) {
+					jackson2ObjectMapperBuilder.dateFormat(new MyDateFormat());
+				}
+			};
+		}
+
+	}
+
 	protected static final class Foo {
 
 		private String name;