Make Joda DateTime serialization format configurable

We allow the serialization format of dates to be configured using
spring.jackson.date-format. However, this property only applies to
java.util.Date instances and has no effect on a Joda DateTime.

This commit updates our auto-configuration for Jackson to allow
the format string that is used to  serialize a Joda DateTime to be
configured. A new property, spring.jackson.joda-date-time-format has
been introduced. When configured, it is used to configure the
serialization format for a Joda DateTime. When it is not configured,
we fall back to using spring.jackson.date-format. If this fails,
either because the format string is incompatible (unlikely) or because
the user's configured the fully-qualified name of a DateFormat class,
a warning is logged encouraging the use of
spring.jackson.joda-date-time-format.

Fixes gh-2225

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

@@ -25,6 +25,10 @@ import java.util.Map.Entry;
 
 import javax.annotation.PostConstruct;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.joda.time.DateTime;
+import org.joda.time.format.DateTimeFormat;
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.beans.factory.ListableBeanFactory;
@@ -47,6 +51,9 @@ import com.fasterxml.jackson.databind.Module;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.PropertyNamingStrategy;
 import com.fasterxml.jackson.databind.SerializationFeature;
+import com.fasterxml.jackson.databind.module.SimpleModule;
+import com.fasterxml.jackson.datatype.joda.ser.DateTimeSerializer;
+import com.fasterxml.jackson.datatype.joda.ser.JacksonJodaFormat;
 
 /**
  * Auto configuration for Jackson. The following auto-configuration will get applied:
@@ -97,6 +104,50 @@ public class JacksonAutoConfiguration {
 
 	}
 
+	@Configuration
+	@ConditionalOnClass({ Jackson2ObjectMapperBuilder.class, DateTime.class,
+			DateTimeSerializer.class })
+	static class JodaDateTimeJacksonConfiguration {
+
+		private final Log log = LogFactory.getLog(JodaDateTimeJacksonConfiguration.class);
+
+		@Autowired
+		private JacksonProperties jacksonProperties;
+
+		@Bean
+		public Module jodaDateTimeSerializationModule() {
+			SimpleModule module = new SimpleModule();
+
+			JacksonJodaFormat jacksonJodaFormat = null;
+
+			if (this.jacksonProperties.getJodaDateTimeFormat() != null) {
+				jacksonJodaFormat = new JacksonJodaFormat(DateTimeFormat.forPattern(
+						this.jacksonProperties.getJodaDateTimeFormat()).withZoneUTC());
+			}
+			else if (this.jacksonProperties.getDateFormat() != null) {
+				try {
+					jacksonJodaFormat = new JacksonJodaFormat(DateTimeFormat.forPattern(
+							this.jacksonProperties.getDateFormat()).withZoneUTC());
+				}
+				catch (IllegalArgumentException ex) {
+					if (this.log.isWarnEnabled()) {
+						this.log.warn("spring.jackson.date-format could not be used to "
+								+ "configure formatting of Joda's DateTime. You may want "
+								+ "to configure spring.jackson.joda-date-time-format as "
+								+ "well.");
+					}
+				}
+			}
+
+			if (jacksonJodaFormat != null) {
+				module.addSerializer(DateTime.class, new DateTimeSerializer(
+						jacksonJodaFormat));
+			}
+
+			return module;
+		}
+	}
+
 	@Configuration
 	@ConditionalOnClass({ ObjectMapper.class, Jackson2ObjectMapperBuilder.class })
 	@EnableConfigurationProperties({ HttpMapperProperties.class, JacksonProperties.class })

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

@@ -43,6 +43,13 @@ public class JacksonProperties {
 	 */
 	private String dateFormat;
 
+	/**
+	 * Joda date time format string (yyyy-MM-dd HH:mm:ss). If not configured,
+	 * {@code date-format} will be used as a fallback if it is configured with a format
+	 * string.
+	 */
+	private String jodaDateTimeFormat;
+
 	/**
 	 * One of the constants on Jackson's PropertyNamingStrategy
 	 * (CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES). Can also be a fully-qualified class
@@ -83,6 +90,14 @@ public class JacksonProperties {
 		this.dateFormat = dateFormat;
 	}
 
+	public String getJodaDateTimeFormat() {
+		return this.jodaDateTimeFormat;
+	}
+
+	public void setJodaDateTimeFormat(String jodaDataTimeFormat) {
+		this.jodaDateTimeFormat = jodaDataTimeFormat;
+	}
+
 	public String getPropertyNamingStrategy() {
 		return this.propertyNamingStrategy;
 	}

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

@@ -23,6 +23,7 @@ import java.util.HashSet;
 import java.util.Set;
 
 import org.joda.time.DateTime;
+import org.joda.time.DateTimeZone;
 import org.joda.time.LocalDateTime;
 import org.junit.After;
 import org.junit.Before;
@@ -134,6 +135,23 @@ public class JacksonAutoConfigurationTests {
 				"spring.jackson.date-format:yyyyMMddHHmmss");
 		this.context.refresh();
 		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		DateTime dateTime = new DateTime(1988, 6, 25, 20, 30, DateTimeZone.UTC);
+		assertEquals("\"19880625203000\"", mapper.writeValueAsString(dateTime));
+		dateTime = new DateTime(1988, 6, 25, 20, 30);
+		Date date = dateTime.toDate();
+		assertEquals("\"19880625203000\"", mapper.writeValueAsString(date));
+	}
+
+	@Test
+	public void customJodaDateTimeFormat() throws Exception {
+		this.context.register(JacksonAutoConfiguration.class);
+		EnvironmentTestUtils.addEnvironment(this.context,
+				"spring.jackson.date-format:yyyyMMddHHmmss",
+				"spring.jackson.joda-date-time-format:yyyy-MM-dd HH:mm:ss");
+		this.context.refresh();
+		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		DateTime dateTime = new DateTime(1988, 6, 25, 20, 30, DateTimeZone.UTC);
+		assertEquals("\"1988-06-25 20:30:00\"", mapper.writeValueAsString(dateTime));
 		Date date = new DateTime(1988, 6, 25, 20, 30).toDate();
 		assertEquals("\"19880625203000\"", mapper.writeValueAsString(date));
 	}
@@ -147,6 +165,8 @@ public class JacksonAutoConfigurationTests {
 						"spring.jackson.date-format:org.springframework.boot.autoconfigure.jackson.JacksonAutoConfigurationTests.MyDateFormat");
 		this.context.refresh();
 		ObjectMapper mapper = this.context.getBean(ObjectMapper.class);
+		DateTime dateTime = new DateTime(1988, 6, 25, 20, 30, DateTimeZone.UTC);
+		assertEquals("\"1988-06-25T20:30:00.000Z\"", mapper.writeValueAsString(dateTime));
 		Date date = new DateTime(1988, 6, 25, 20, 30).toDate();
 		assertEquals("\"1988-06-25 20:30:00\"", mapper.writeValueAsString(date));
 	}