Spring + Jackson + joda time: how to specify the serialization/deserialization format? - spring-mvc

Question

I have the following class:
public static class ARestRequestParam
{
String name;
LocalDate date; // joda type
}
And I want it to be deserialized from the following JSON which is processed by jackson.
{ name:"abc", date:"20131217" }
Actually, I want to deserialize any LocalDate field in any class with "yyyyMMdd" format, without duplicating the format string, without adding any setter method, without any XML configuration. (That is, annotation and Java code is preferable)
How can it be done?
Also, I also want to know the serialization part. that is, LocalDate -> "yyyyMMdd".
I've seen followings:
jackson-datatype-joda (https://github.com/FasterXML/jackson-datatype-joda)
custom serializer (public class JodaDateTimeJsonSerializer extends JsonSerializer { ... } - Spring #ResponseBody Jackson JsonSerializer with JodaTime)
#JsonCreator
#DateTimeFormat
But I don't know which is applicable, and which is most up-to-date.
BTW, I use Spring Boot.
UPDATE
Ok, I have managed to write working code for the deserialization part.
It is as follows:
#Configuration
#EnableWebMvc
public class WebMvcConfiguration extends WebMvcConfigurerAdapter
{
#Override
public void configureMessageConverters(
List<HttpMessageConverter<?>> converters)
{
converters.add(jacksonConverter());
}
#Bean
public MappingJackson2HttpMessageConverter jacksonConverter()
{
MappingJackson2HttpMessageConverter converter =
new MappingJackson2HttpMessageConverter();
ObjectMapper mapper = new ObjectMapper();
mapper.registerModule(new ApiJodaModule());
converter.setObjectMapper(mapper);
return converter;
}
#SuppressWarnings("serial")
private class ApiJodaModule extends SimpleModule
{
public ApiJodaModule()
{
addDeserializer(LocalDate.class, new ApiLocalDateDeserializer());
}
}
#SuppressWarnings("serial")
private static class ApiLocalDateDeserializer
extends StdScalarDeserializer<LocalDate>
{
private static DateTimeFormatter formatter =
DateTimeFormat.forPattern("yyyyMMdd");
public ApiLocalDateDeserializer() { super(LocalDate.class); }
#Override
public LocalDate deserialize(JsonParser jp, DeserializationContext ctxt)
throws IOException, JsonProcessingException
{
if (jp.getCurrentToken() == JsonToken.VALUE_STRING)
{
String s = jp.getText().trim();
if (s.length() == 0)
return null;
return LocalDate.parse(s, formatter);
}
throw ctxt.wrongTokenException(jp, JsonToken.NOT_AVAILABLE,
"expected JSON Array, String or Number");
}
}
}
I had to implement the deserializer myself, since the datetime format for the deserializer in jackson-datatype-joda cannot be altered. So, since I've implemented the deserializer myself, jackson-datatype-joda is not needed. (although I've copied pieces of its code)
Is this code Ok?
Is this up-to-date solution?
Is there any other easier way?
Any suggestion would be greatly appreciated.
UPDATE
Following Dave Syer's suggestion, I modified the source above as follows:
Removed 2 methods: configureMessageConverters(), jacksonConverter()
Added following method into WebMvcConfiguration class:
#Bean
public Module apiJodaModule()
{
return new ApiJodaModule();
}
But now it does not work. It seems apiJodaModule() is ignored.
How can I make it work?
(It seems that I should not have a class that has #EnableWebMvc to use that feature.)
The version I use is org.springframework.boot:spring-boot-starter-web:0.5.0.M6.
UPDATE
Final working version is as follows: (with other configurations I've done previously in the class that had #EnableWebMvc)
As Dave Syer mentioned, this will only work on BUILD-SNAPSHOT version, at least for now.
#Configuration
public class WebMvcConfiguration
{
#Bean
public WebMvcConfigurerAdapter apiWebMvcConfiguration()
{
return new ApiWebMvcConfiguration();
}
#Bean
public UserInterceptor userInterceptor()
{
return new UserInterceptor();
}
public class ApiWebMvcConfiguration extends WebMvcConfigurerAdapter
{
#Override
public void addInterceptors(InterceptorRegistry registry)
{
registry.addInterceptor(userInterceptor())
.addPathPatterns("/api/user/**");
}
#Override
public void addResourceHandlers(ResourceHandlerRegistry registry)
{
registry.addResourceHandler("/**")
.addResourceLocations("/")
.setCachePeriod(0);
}
}
#Bean
public Module apiJodaModule()
{
return new ApiJodaModule();
}
#SuppressWarnings("serial")
private static class ApiJodaModule extends SimpleModule
{
public ApiJodaModule()
{
addDeserializer(LocalDate.class, new ApiLocalDateDeserializer());
}
private static final class ApiLocalDateDeserializer
extends StdScalarDeserializer<LocalDate>
{
public ApiLocalDateDeserializer() { super(LocalDate.class); }
#Override
public LocalDate deserialize(JsonParser jp,
DeserializationContext ctxt)
throws IOException, JsonProcessingException
{
if (jp.getCurrentToken() == JsonToken.VALUE_STRING)
{
String s = jp.getText().trim();
if (s.length() == 0)
return null;
return LocalDate.parse(s, localDateFormatter);
}
throw ctxt.mappingException(LocalDate.class);
}
}
private static DateTimeFormatter localDateFormatter =
DateTimeFormat.forPattern("yyyyMMdd");
}
}

Answer 1

Your code is OK, but if you use #EnableWebMvc in a Spring Boot app you switch off the default settings in the framework, so maybe you should avoid that. Also, you now have only one HttpMessageConverter in your MVC handler adapter. If you use a snapshot of Spring Boot you ought to be able to simply define a #Bean of type Module and everything else would be automatic, so I would recommend doing it that way.