Allow Jackson features to be configured via the environment

Enhance JacksonAutoConfiguration to configure features on the
ObjectMapper it creates based on the following configuration
properties:

spring.jackson.deserialization.* = true|false
spring.jackson.generator.* = true|false
spring.jackson.mapper.* = true|false
spring.jackson.parser.* = true|false
spring.jackson.serialization.* = true|false

The final part of each property name maps onto an enum. The enums are:

deserialization: com.fasterxml.jackson.databind.DeserializationFeature
generator: com.fasterxml.jackson.core.JsonGenerator.Feature
mapper: com.fasterxml.jackson.databind.MapperFeature
parser: com.fasterxml.jackson.core.JsonParser.Feature
serialization: com.fasterxml.jackson.databind.SerializationFeature

Closes gh-1227

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

@@ -17,6 +17,7 @@
 package org.springframework.boot.autoconfigure.jackson;
 
 import java.util.Collection;
+import java.util.Map.Entry;
 
 import javax.annotation.PostConstruct;
 
@@ -33,6 +34,10 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.MapperFeature;
 import com.fasterxml.jackson.databind.Module;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
@@ -51,6 +56,7 @@ import com.fasterxml.jackson.datatype.jsr310.JSR310Module;
  * </ul>
  *
  * @author Oliver Gierke
+ * @author Andy Wilkinson
  * @since 1.1.0
  */
 @Configuration
@@ -75,24 +81,73 @@ public class JacksonAutoConfiguration {
 
 	@Configuration
 	@ConditionalOnClass(ObjectMapper.class)
-	@EnableConfigurationProperties(HttpMapperProperties.class)
+	@EnableConfigurationProperties({ HttpMapperProperties.class, JacksonProperties.class })
 	static class JacksonObjectMapperAutoConfiguration {
 
 		@Autowired
-		private HttpMapperProperties properties = new HttpMapperProperties();
+		private HttpMapperProperties httpMapperProperties = new HttpMapperProperties();
+
+		@Autowired
+		private JacksonProperties jacksonProperties = new JacksonProperties();
 
 		@Bean
 		@Primary
 		@ConditionalOnMissingBean
 		public ObjectMapper jacksonObjectMapper() {
 			ObjectMapper objectMapper = new ObjectMapper();
-			if (this.properties.isJsonSortKeys()) {
+
+			if (this.httpMapperProperties.isJsonSortKeys()) {
 				objectMapper.configure(SerializationFeature.ORDER_MAP_ENTRIES_BY_KEYS,
 						true);
 			}
+
+			configureDeserializationFeatures(objectMapper);
+			configureSerializationFeatures(objectMapper);
+			configureMapperFeatures(objectMapper);
+			configureParserFeatures(objectMapper);
+			configureGeneratorFeatures(objectMapper);
+
 			return objectMapper;
 		}
 
+		private void configureDeserializationFeatures(ObjectMapper objectMapper) {
+			for (Entry<DeserializationFeature, Boolean> entry : this.jacksonProperties
+					.getDeserialization().entrySet()) {
+				objectMapper.configure(entry.getKey(), isFeatureEnabled(entry));
+			}
+		}
+
+		private void configureSerializationFeatures(ObjectMapper objectMapper) {
+			for (Entry<SerializationFeature, Boolean> entry : this.jacksonProperties
+					.getSerialization().entrySet()) {
+				objectMapper.configure(entry.getKey(), isFeatureEnabled(entry));
+			}
+		}
+
+		private void configureMapperFeatures(ObjectMapper objectMapper) {
+			for (Entry<MapperFeature, Boolean> entry : this.jacksonProperties.getMapper()
+					.entrySet()) {
+				objectMapper.configure(entry.getKey(), isFeatureEnabled(entry));
+			}
+		}
+
+		private void configureParserFeatures(ObjectMapper objectMapper) {
+			for (Entry<JsonParser.Feature, Boolean> entry : this.jacksonProperties
+					.getParser().entrySet()) {
+				objectMapper.configure(entry.getKey(), isFeatureEnabled(entry));
+			}
+		}
+
+		private void configureGeneratorFeatures(ObjectMapper objectMapper) {
+			for (Entry<JsonGenerator.Feature, Boolean> entry : this.jacksonProperties
+					.getGenerator().entrySet()) {
+				objectMapper.configure(entry.getKey(), isFeatureEnabled(entry));
+			}
+		}
+
+		private boolean isFeatureEnabled(Entry<?, Boolean> entry) {
+			return entry.getValue() != null && entry.getValue();
+		}
 	}
 
 	@Configuration

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

@@ -0,0 +1,68 @@
+/*
+ * 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.autoconfigure.jackson;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.databind.DeserializationFeature;
+import com.fasterxml.jackson.databind.MapperFeature;
+import com.fasterxml.jackson.databind.SerializationFeature;
+
+/**
+ * Configuration properties to configure Jackson
+ *
+ * @author Andy Wilkinson
+ */
+@ConfigurationProperties(prefix = "spring.jackson")
+public class JacksonProperties {
+
+	private Map<SerializationFeature, Boolean> serialization = new HashMap<SerializationFeature, Boolean>();
+
+	private Map<DeserializationFeature, Boolean> deserialization = new HashMap<DeserializationFeature, Boolean>();
+
+	private Map<MapperFeature, Boolean> mapper = new HashMap<MapperFeature, Boolean>();
+
+	private Map<JsonParser.Feature, Boolean> parser = new HashMap<JsonParser.Feature, Boolean>();
+
+	private Map<JsonGenerator.Feature, Boolean> generator = new HashMap<JsonGenerator.Feature, Boolean>();
+
+	public Map<SerializationFeature, Boolean> getSerialization() {
+		return this.serialization;
+	}
+
+	public Map<DeserializationFeature, Boolean> getDeserialization() {
+		return this.deserialization;
+	}
+
+	public Map<MapperFeature, Boolean> getMapper() {
+		return this.mapper;
+	}
+
+	public Map<JsonParser.Feature, Boolean> getParser() {
+		return this.parser;
+	}
+
+	public Map<JsonGenerator.Feature, Boolean> getGenerator() {
+		return this.generator;
+	}
+
+}

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

@@ -25,16 +25,21 @@ import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
 import org.springframework.boot.autoconfigure.web.HttpMessageConvertersAutoConfiguration;
+import org.springframework.boot.test.EnvironmentTestUtils;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Primary;
 
 import com.fasterxml.jackson.core.JsonGenerator;
+import com.fasterxml.jackson.core.JsonParser;
 import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.DeserializationFeature;
 import com.fasterxml.jackson.databind.JsonSerializer;
+import com.fasterxml.jackson.databind.MapperFeature;
 import com.fasterxml.jackson.databind.Module;
 import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.databind.SerializerProvider;
 import com.fasterxml.jackson.databind.module.SimpleModule;
 import com.fasterxml.jackson.datatype.joda.JodaModule;
@@ -44,7 +49,9 @@ import static org.hamcrest.Matchers.hasItem;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertThat;
+import static org.junit.Assert.assertTrue;
 import static org.mockito.Matchers.argThat;
 import static org.mockito.Mockito.verify;
 
@@ -101,6 +108,128 @@ public class JacksonAutoConfigurationTests {
 		assertEquals("{\"foo\":\"bar\"}", mapper.writeValueAsString(new Foo()));
 	}
 
+	@Test
+	public void enableSerializationFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.serialization.indent_output:true");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertFalse(SerializationFeature.INDENT_OUTPUT.enabledByDefault());
+		assertTrue(mapper.getSerializationConfig().hasSerializationFeatures(
+				SerializationFeature.INDENT_OUTPUT.getMask()));
+	}
+
+	@Test
+	public void disableSerializationFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.serialization.write_dates_as_timestamps:false");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertTrue(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS.enabledByDefault());
+		assertFalse(mapper.getSerializationConfig().hasSerializationFeatures(
+				SerializationFeature.WRITE_DATES_AS_TIMESTAMPS.getMask()));
+	}
+
+	@Test
+	public void enableDeserializationFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.deserialization.use_big_decimal_for_floats:true");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertFalse(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS.enabledByDefault());
+		assertTrue(mapper.getDeserializationConfig().hasDeserializationFeatures(
+				DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS.getMask()));
+	}
+
+	@Test
+	public void disableDeserializationFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.deserialization.fail_on_unknown_properties:false");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertTrue(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES.enabledByDefault());
+		assertFalse(mapper.getDeserializationConfig().hasDeserializationFeatures(
+				DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES.getMask()));
+	}
+
+	@Test
+	public void enableMapperFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.mapper.require_setters_for_getters:true");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertFalse(MapperFeature.REQUIRE_SETTERS_FOR_GETTERS.enabledByDefault());
+		assertTrue(mapper.getSerializationConfig().hasMapperFeatures(
+				MapperFeature.REQUIRE_SETTERS_FOR_GETTERS.getMask()));
+		assertTrue(mapper.getDeserializationConfig().hasMapperFeatures(
+				MapperFeature.REQUIRE_SETTERS_FOR_GETTERS.getMask()));
+	}
+
+	@Test
+	public void disableMapperFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.mapper.use_annotations:false");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertTrue(MapperFeature.USE_ANNOTATIONS.enabledByDefault());
+		assertFalse(mapper.getDeserializationConfig().hasMapperFeatures(
+				MapperFeature.USE_ANNOTATIONS.getMask()));
+		assertFalse(mapper.getSerializationConfig().hasMapperFeatures(
+				MapperFeature.USE_ANNOTATIONS.getMask()));
+	}
+
+	@Test
+	public void enableParserFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.parser.allow_single_quotes:true");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertFalse(JsonParser.Feature.ALLOW_SINGLE_QUOTES.enabledByDefault());
+		assertTrue(mapper.getFactory().isEnabled(JsonParser.Feature.ALLOW_SINGLE_QUOTES));
+	}
+
+	@Test
+	public void disableParserFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.parser.auto_close_source:false");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertTrue(JsonParser.Feature.AUTO_CLOSE_SOURCE.enabledByDefault());
+		assertFalse(mapper.getFactory().isEnabled(JsonParser.Feature.AUTO_CLOSE_SOURCE));
+	}
+
+	@Test
+	public void enableGeneratorFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.generator.write_numbers_as_strings:true");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertFalse(JsonGenerator.Feature.WRITE_NUMBERS_AS_STRINGS.enabledByDefault());
+		assertTrue(mapper.getFactory().isEnabled(
+				JsonGenerator.Feature.WRITE_NUMBERS_AS_STRINGS));
+	}
+
+	@Test
+	public void disableGeneratorFeature() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.generator.auto_close_target:false");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		assertTrue(JsonGenerator.Feature.AUTO_CLOSE_TARGET.enabledByDefault());
+		assertFalse(mapper.getFactory()
+				.isEnabled(JsonGenerator.Feature.AUTO_CLOSE_TARGET));
+	}
+
 	@Configuration
 	protected static class ModulesConfig {
 

spring-boot-docs/src/main/asciidoc/appendix-application-properties.adoc

@@ -88,6 +88,13 @@ content into your application; rather pick only the properties that you need.
 	spring.resources.cache-period= # cache timeouts in headers sent to browser
 	spring.resources.add-mappings=true # if default mappings should be added
 
+	# JACKSON ({sc-spring-boot-autoconfigure}}/jackson/JacksonProperties.{sc-ext}[JacksonProperties])
+	spring.jackson.deserialization.*= # see Jackson's DeserializationFeature
+	spring.jackson.generator.*= # see Jackson's JsonGenerator.Feature
+	spring.jackson.mapper.*= # see Jackson's MapperFeature
+	spring.jackson.parser.*= # see Jackson's JsonParser.Feature
+	spring.jackson.serialization.*= # see Jackson's SerializationFeature
+
 	# THYMELEAF ({sc-spring-boot-autoconfigure}/thymeleaf/ThymeleafAutoConfiguration.{sc-ext}[ThymeleafAutoConfiguration])
 	spring.thymeleaf.prefix=classpath:/templates/
 	spring.thymeleaf.suffix=.html

spring-boot-docs/src/main/asciidoc/howto.adoc

@@ -654,15 +654,43 @@ conversion in an HTTP exchange. If Jackson is on the classpath you already get a
 converter with a vanilla `ObjectMapper`. Spring Boot has some features to make it easier
 to customize this behavior.
 
-The smallest change that might work is to just add beans of type
-`com.fasterxml.jackson.databind.Module` to your context. They will be registered with the
-default `ObjectMapper` and then injected into the default message converter. To replace
-the default `ObjectMapper` completely, define a `@Bean` of that type and mark it as
-`@Primary`.
-
-In addition, if your context contains any beans of type `ObjectMapper` then all of the
-`Module` beans will be registered with all of the mappers. So there is a global mechanism
-for contributing custom modules when you add new features to your application.
+You can configure the vanilla `ObjectMapper` using the environment. Jackson provides an
+extensive suite of simple on/off features that can be used to configure various aspects
+of its processing. These features are described in five enums in Jackson which map onto
+properties in the environment:
+
+|===
+|Jackson enum|Environment property
+
+|`com.fasterxml.jackson.databind.DeserializationFeature`
+|`spring.jackson.deserialization.<feature_name>=true\|false`
+
+|`com.fasterxml.jackson.core.JsonGenerator.Feature`
+|`spring.jackson.generator.<feature_name>=true\|false`
+
+|`com.fasterxml.jackson.databind.MapperFeature`
+|`spring.jackson.mapper.<feature_name>=true\|false`
+
+|`com.fasterxml.jackson.core.JsonParser.Feature`
+|`spring.jackson.parser.<feature_name>=true\|false`
+
+|`com.fasterxml.jackson.databind.SerializationFeature`
+|`spring.jackson.serialization.<feature_name>=true\|false`
+|===
+
+For example, to allow deserialization to continue when an unknown property is encountered
+during deserialization, set `spring.jackson.deserialization.fail_on_unknown_properties=false`.
+Note that, thanks to the use of <<boot-features-external-config-relaxed-binding, relaxed binding>>,
+the case of `fail_on_unknown_properties` doesn't have to match the case of the corresponding
+enum constant which is `FAIL_ON_UNKNOWN_PROPERTIES`.
+
+If you want to replace the default `ObjectMapper` completely, define a `@Bean` of that type
+and mark it as `@Primary`.
+
+Another way to customize Jackson is to add beans of type
+`com.fasterxml.jackson.databind.Module` to your context. They will be registered with every
+bean of type `ObjectMapper`, providing a global mechanism for contributing custom modules
+when you add new features to your application.
 
 Finally, if you provide any `@Beans` of type `MappingJackson2HttpMessageConverter` then
 they will replace the default value in the MVC configuration. Also, a convenience bean is