my goal is to configure the objectMapper
in the way that it only serialises element which are annotated with @JsonProperty
.
In order to do
I've used this with Jackson 2.x and Spring 3.1.2+
servlet-context.xml:
Note that the root element is <beans:beans>
, so you may need to remove beans
and add mvc
to some of these elements depending on your setup.
<annotation-driven>
<message-converters>
<beans:bean
class="org.springframework.http.converter.StringHttpMessageConverter" />
<beans:bean
class="org.springframework.http.converter.ResourceHttpMessageConverter" />
<beans:bean
class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<beans:property name="objectMapper" ref="jacksonObjectMapper" />
</beans:bean>
</message-converters>
</annotation-driven>
<beans:bean id="jacksonObjectMapper"
class="au.edu.unimelb.atcom.transfer.json.mappers.JSONMapper" />
au.edu.unimelb.atcom.transfer.json.mappers.JSONMapper.java:
public class JSONMapper extends ObjectMapper {
public JSONMapper() {
SimpleModule module = new SimpleModule("JSONModule", new Version(2, 0, 0, null, null, null));
module.addSerializer(Date.class, new DateSerializer());
module.addDeserializer(Date.class, new DateDeserializer());
// Add more here ...
registerModule(module);
}
}
DateSerializer.java:
public class DateSerializer extends StdSerializer<Date> {
public DateSerializer() {
super(Date.class);
}
@Override
public void serialize(Date date, JsonGenerator json,
SerializerProvider provider) throws IOException,
JsonGenerationException {
// The client side will handle presentation, we just want it accurate
DateFormat df = StdDateFormat.getBlueprintISO8601Format();
String out = df.format(date);
json.writeString(out);
}
}
DateDeserializer.java:
public class DateDeserializer extends StdDeserializer<Date> {
public DateDeserializer() {
super(Date.class);
}
@Override
public Date deserialize(JsonParser json, DeserializationContext context)
throws IOException, JsonProcessingException {
try {
DateFormat df = StdDateFormat.getBlueprintISO8601Format();
return df.parse(json.getText());
} catch (ParseException e) {
return null;
}
}
}
I am using Spring 3.2.4 and Jackson FasterXML 2.1.1.
I have created a custom JacksonObjectMapper that works with explicit annotations for each attribute of the Objects mapped:
package com.test;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
public class MyJaxbJacksonObjectMapper extends ObjectMapper {
public MyJaxbJacksonObjectMapper() {
this.setVisibility(PropertyAccessor.FIELD, JsonAutoDetect.Visibility.ANY)
.setVisibility(PropertyAccessor.CREATOR, JsonAutoDetect.Visibility.ANY)
.setVisibility(PropertyAccessor.SETTER, JsonAutoDetect.Visibility.NONE)
.setVisibility(PropertyAccessor.GETTER, JsonAutoDetect.Visibility.NONE)
.setVisibility(PropertyAccessor.IS_GETTER, JsonAutoDetect.Visibility.NONE);
this.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
}
}
Then this is instantiated in the context-configuration (servlet-context.xml):
<mvc:annotation-driven>
<mvc:message-converters>
<beans:bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<beans:property name="objectMapper">
<beans:bean class="com.test.MyJaxbJacksonObjectMapper" />
</beans:property>
</beans:bean>
</mvc:message-converters>
</mvc:annotation-driven>
This works fine!
Above Spring 4, there is no need to configure MappingJacksonHttpMessageConverter
if you only intend to configure ObjectMapper
.
(configure MappingJacksonHttpMessageConverter
will cause you to lose other MessageConverter)
You just need to do:
public class MyObjectMapper extends ObjectMapper {
private static final long serialVersionUID = 4219938065516862637L;
public MyObjectMapper() {
super();
enable(SerializationFeature.INDENT_OUTPUT);
}
}
And in your Spring configuration, create this bean:
@Bean
public MyObjectMapper myObjectMapper() {
return new MyObjectMapper();
}
I am using Spring 4.1.6 and Jackson FasterXML 2.1.4.
<mvc:annotation-driven>
<mvc:message-converters>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<property name="objectMapper">
<bean class="com.fasterxml.jackson.databind.ObjectMapper">
<!-- 设置不输出null字段-->
<property name="serializationInclusion" value="NON_NULL"/>
</bean>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>
this works at my applicationContext.xml configration
SOLUTION 1
First working solution (tested) useful especially when using @EnableWebMvc:
@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
@Autowired
private ObjectMapper objectMapper;// created elsewhere
@Override
public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
// this won't add a 2nd MappingJackson2HttpMessageConverter
// as the SOLUTION 2 is doing but also might seem complicated
converters.stream().filter(c -> c instanceof MappingJackson2HttpMessageConverter).forEach(c -> {
// check default included objectMapper._registeredModuleTypes,
// e.g. Jdk8Module, JavaTimeModule when creating the ObjectMapper
// without Jackson2ObjectMapperBuilder
((MappingJackson2HttpMessageConverter) c).setObjectMapper(this.objectMapper);
});
}
SOLUTION 2
Of course the common approach below works too (also working with @EnableWebMvc):
@Configuration
@EnableWebMvc
public class WebConfig implements WebMvcConfigurer {
@Autowired
private ObjectMapper objectMapper;// created elsewhere
@Override
public void extendMessageConverters(List<HttpMessageConverter<?>> converters) {
// this will add a 2nd MappingJackson2HttpMessageConverter
// (additional to the default one) but will work and you
// won't lose the default converters as you'll do when overwriting
// configureMessageConverters(List<HttpMessageConverter<?>> converters)
//
// you still have to check default included
// objectMapper._registeredModuleTypes, e.g.
// Jdk8Module, JavaTimeModule when creating the ObjectMapper
// without Jackson2ObjectMapperBuilder
converters.add(new MappingJackson2HttpMessageConverter(this.objectMapper));
}
Why @EnableWebMvc usage is a problem?
@EnableWebMvc is using DelegatingWebMvcConfiguration
which extends WebMvcConfigurationSupport
which does this:
if (jackson2Present) {
Jackson2ObjectMapperBuilder builder = Jackson2ObjectMapperBuilder.json();
if (this.applicationContext != null) {
builder.applicationContext(this.applicationContext);
}
messageConverters.add(new MappingJackson2HttpMessageConverter(builder.build()));
}
which means that there's no way of injecting your own ObjectMapper
with the purpose of preparing it to be used for creating the default MappingJackson2HttpMessageConverter
when using @EnableWebMvc.
Using Spring Boot (1.2.4) and Jackson (2.4.6) the following annotation based configuration worked for me.
@Configuration
public class JacksonConfiguration {
@Bean
public ObjectMapper objectMapper() {
ObjectMapper mapper = new ObjectMapper();
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
mapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, true);
return mapper;
}
}