I am looking to extend JacksonAutoConfiguration specifically when the builder is created, i would like to set that ObjectMapper to a Util class which has static setter for the ObjectMapper. Look at the line before returning builder where I would like to set ObjectMpper to a static class.
#Bean
#ConditionalOnMissingBean(Jackson2ObjectMapperBuilder.class)
public Jackson2ObjectMapperBuilder jacksonObjectMapperBuilder() {
Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
builder.applicationContext(this.applicationContext);
if (this.jacksonProperties.getSerializationInclusion() != null) {
builder.serializationInclusion(this.jacksonProperties
.getSerializationInclusion());
}
configureFeatures(builder, this.jacksonProperties.getDeserialization());
configureFeatures(builder, this.jacksonProperties.getSerialization());
configureFeatures(builder, this.jacksonProperties.getMapper());
configureFeatures(builder, this.jacksonProperties.getParser());
configureFeatures(builder, this.jacksonProperties.getGenerator());
configureDateFormat(builder);
configurePropertyNamingStrategy(builder);
configureModules(builder);
**ObjectMapperUtils.setObjectMapper( builder.build() );**
return builder;
}
The ObjectMapper created from the auto-configured Jackson2ObjectMapperBuilder is exposed as a bean in the JacksonAutoConfiguration. You could simply create another #Configuration class, get a reference to the ObjectMapper (via auto-wiring) and use an #PostConstruct method to set the ObjectMapper in your ObjectMapperUtils class.
Another suggestion would be to refactor ObjectMapperUtils so that it is created as a Spring bean itself, then you can auto-wire ObjectMapper directly into it.
Related
I am using spring.
I have a configured ObjectMapper for the entire project and I use it to set up a kafka deserializer.
And then I need a custom kafka deserializer to be used in KafkaListener.
I'm configuring KafkaListener via autoconfiguration, not via #Configuration class.
#Component
#RequiredArgsConstructor
public class CustomMessageDeserializer implements Deserializer<MyMessage> {
private final ObjectMapper objectMapper;
#SneakyThrows
#Override
public MyMessage deserialize(String topic, byte[] data) {
return objectMapper.readValue(data, MyMessage.class);
}
}
If i do like this
#KafkaListener(
topics = {"${topics.invite-user-topic}"},
properties = {"value.deserializer=com.service.deserializer.CustomMessageDeserializer"}
)
public void receiveInviteUserMessages(MyMessage myMessage) {}
I received KafkaException: Could not find a public no-argument constructor
But with public no-argument constructor in CustomMessageDeserializer class i am getting NPE because ObjectMapper = null. It creates and uses a new class, not a spring component.
#KafkaListener supports SpEL expressions.
And I think that this problem can be solved using SpEL.
Do you have any idea how to inject spring bean CustomMessageDeserializer with SpEL?
There are no easy ways to do it with SPeL.
Analysis
To get started, see the JavaDoc for #KafkaListener#properties:
/**
*
* SpEL expressions must resolve to a String ...
*/
The value of value.deserializer is used to instantiate the specified deserializer class. Let's follow the call chain:
You specify this value in the #KafkaListener annotation, then you are probably not creating a bean of the ConsumerFactory.class. So Spring creates this bean class itself - see KafkaAutoConfiguration#kafkaConsumerFactory.
Next is the creation of the returned object new DefaultKafkaConsumerFactory(...) as ConsumerFactory<?,?> using the constructor for default delivery expressions keyDeserializer/valueDeserializer = () -> null
This factory is used to create a Kafka consumer (The entry point is the constructor KafkaMessageListenerContainer#ListenerConsumer, then KafkaMessageListenerContainer.this.consumerFactory.createConsumer...)
In the KafkaConsumer constructor, the valueDeserializer object is being created, because it is null (for the default factory of point 2 above):
if (valueDeserializer == null) {
this.valueDeserializer = config.getConfiguredInstance(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, Deserializer.class);
The implementation of config.getConfiguredInstance involves instantiating your deserializer class via a parameterless constructor using reflection and your String "com.service.deserializer.CustomMessageDeserializer" class name
Solutions
To use value.deserializer with your customized ObjectMapper, you must create the ConsumerFactory bean yourself using the setValueDeserializer(...) method. This is also mentioned in the second Important part of the JSON.Mapping_Types.Important documentation
If you don't want to create a ConsumerFactory bean, and also don't have complicated logic in your deserializer (you only have return objectMapper.readValue(data, MyMessage.class);), then register DefaultKafkaConsumerFactoryCustomizer:
#Bean
// inject your custom objectMapper
public DefaultKafkaConsumerFactoryCustomizer customizeJsonDeserializer(ObjectMapper objectMapper) {
return consumerFactory ->
consumerFactory.setValueDeserializerSupplier(() ->
new org.springframework.kafka.support.serializer.JsonDeserializer<>(objectMapper));
}
In this case, you don't need to create your own CustomMessageDeserializer class (remove it) and Spring will automatically parse the message into your MyMessage.
#KafkaListener annotation should also not contains the property properties = {"value.deserializer=com.my.kafka_test.component.CustomMessageDeserializer"}. This DefaultKafkaConsumerFactoryCustomizer bean will automatically be used to configure the default ConsumerFactory<?, ?> (see the implementation of the KafkaAutoConfiguration#kafkaConsumerFactory method)
Here how it works for me:
#KafkaListener(topics = "${solr.kafka.topic}", containerFactory = "batchFactory")
public void listen(List<SolrInputDocument> docs, #Header(KafkaHeaders.BATCH_CONVERTED_HEADERS) List<Map<String, Object>> headers, Acknowledgment ack) throws IOException {...}
And then I have 2 beans defined in my Configuration
#Profile("!test")
#Bean
#Autowired
public ConsumerFactory<String, SolrInputDocument> consumerFactory(KafkaProperties properties) {
Map<String, Object> props = properties.buildConsumerProperties();
props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, false);
DefaultKafkaConsumerFactory<String, SolrInputDocument> result = new DefaultKafkaConsumerFactory<>(props);
String validatedKeyDeserializerName = KafkaMessageType.valueOf(keyDeserializerName).toString();
ZiDeserializer<SolrInputDocument> deserializer = ZiDeserializerFactory.getInstance(validatedKeyDeserializerName);
result.setValueDeserializer(deserializer);
return result;
}
#Profile("!test")
#Bean
#Autowired
public ConcurrentKafkaListenerContainerFactory<String, SolrInputDocument> batchFactory(ConsumerFactory<String, SolrInputDocument> consumerFactory) {
ConcurrentKafkaListenerContainerFactory<String, SolrInputDocument> factory = new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(consumerFactory);
factory.setBatchListener(true);
factory.setConcurrency(2);
ExponentialBackOffWithMaxRetries backoff = new ExponentialBackOffWithMaxRetries(10);
backoff.setMultiplier(3); // Default is 1.5 but this seems more reasonable
factory.setCommonErrorHandler(new DefaultErrorHandler(null, backoff));
// Needed for manual commits
factory.getContainerProperties().setAckMode(ContainerProperties.AckMode.MANUAL_IMMEDIATE);
return factory;
}
Note that the interface ZiDeserializer<SolrInputDocument> deserializeris my interface and ZiDeserializerFactory.getInstance(validatedKeyDeserializerName); returns my custom implementation of ZiDeserializer. And ZiDeserializer extends org.apache.kafka.common.serialization.Deserializer. This works for me
As we know, we can configure the global HttpMessageConverter by configureMessageConverters method in WebMvcConfigurer.
see https://docs.spring.io/spring/docs/current/spring-framework-reference/web.html#mvc-config-message-converters
But I want to configure a HttpMessageConverter for specified Controller to override the global configuration to implement the function different from the global.
How should I configure it? Can any friends give me pointers?
You can put below code in any of your configuration classes. and you have to autowire this specific objectmapper in that class where you need.Even you can create multiple objectmappers to serve different purposes.
#Bean
#Qualifier("customForController")
public ObjectMapper getObjectMapper() {
ObjectMapper mapper=new ObjectMapper();
return mapper;
}
#Bean
#Qualifier("customMessageConverter")
public MappingJackson2HttpMessageConverter converter() {
MappingJackson2HttpMessageConverter httConverter = new MappingJackson2HttpMessageConverter();
httConverter.setObjectMapper(getObjectMapper());
//others configuration goes here
return httConverter;
}
I came across a strange behaviour with respect to #Bean and #Autowired in my #Configuration class. My web project structure is like
Controller → Service → Repository
In my Service I have a dependency on ObjectMapper
#Autowired
public ServiceClass(final ObjectMapper objectMapper) {
this.objectMapper = objectMapper;
}
Since I want to use a Java 8 optional class while deserializing, I wanted to register Jdk8Module. So I created a configuration class like this:
#Configuration
public class JacksonConfig {
#Bean
public ObjectMapper objectMapper(final ObjectMapper objectMapper) {
objectMapper.registerModule(new Jdk8Module());
return objectMapper;
}
}
I initially thought that Spring will inject the objectMapper instance which it has, which I can manipulate and return it, so that when I autowire it in my service class, I get the updated instance of ObjectMapper.
But I get a cyclic dependency error. This is understandable because, my bean configuration depends on objectmapper and returns an objectmapper.
But it is surprising, if I change the method to have #Autowired instead of #Bean, Spring doesn't complain and works as expected.
#Autowired
public ObjectMapper objectMapper(final ObjectMapper objectMapper) {
objectMapper.registerModule(new Jdk8Module());
return objectMapper;
}
Why is that?
The #Bean annotation goal is to provide beans from the Spring BeanFactory. When a method is annotated #Bean, it is supposed to return a new instance of an object. It can use paramaters if Spring is able to instantiate them too.
In your example, when you declare
#Bean
public ObjectMapper objectMapper(final ObjectMapper objectMapper) {
objectMapper.registerModule(new Jdk8Module());
return objectMapper;
}
It means your ObjectMapper is a bean (of course) that takes a parameter which is an instance of ObjectMapper and Spring knows ObjectMapper so it can instantiate it using... the very same method. Here is your cyclic dependency.
In the case of #Autowired, Spring uses an ObjectMapper as a parameter of your method that is already in the BeanFactory. That's why it removes the cyclic dependency.
I hope I'm clear enough.
Little reference here : https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/annotation/Bean.html
In
#Autowired
public ObjectMapper objectMapper(final ObjectMapper objectMapper) {
objectMapper.registerModule(new Jdk8Module());
return objectMapper;
}
Someone else is injecting an ObjectMapper (maybe Spring) to this method. I think the Autowired annotation is not necessary in this case, Spring knows you want to inject a bean here.
You aren't creating new beans in this case so you will not have a cyclic dependency error here.
If you want to create a new one, maybe you should play with #Qualifier.
More info: https://dzone.com/articles/spring-configuration-and
This question already has answers here:
Can't set ProblemHandler to ObjectMapper in Spring Boot
(2 answers)
Closed 4 years ago.
As I understood, Spring is already providing a bean for Jackson ObjectMapper. Therefore, instead of creating a new bean, I'm trying to customize this bean.
From this blog post, and then this Github project I used Jackson2ObjectMapperBuilder bean to achieve this customization.
#Bean
public Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder(ApplicationContext context) {
Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
builder.findModulesViaServiceLoader(true);
return builder;
}
Then, I was trying to customize the deserializer in order to make it lenient: if an exception is raised when deserializing a property, I want the result object's property to be null and let the deserialization continue (default is to fail on first property that cannot be deserialized).
I've been able to achieve that with a class NullableFieldsDeserializationProblemHandler that extends DeserializationProblemHandler (I do not think the code is relevant but if needed, I can share it).
The simplest way to register this handler is to use the .addHandler() method of ObjectMapper. But of course, doing like this, I would need to set that every time I inject and use the ObjectMapper. I'd like to be able to configure handler so that every time the ObjectMapper is auto-wired, the handler is already present.
The best solution I came up with so far is to use a #PostConstruct annotation only to register the problem handler.
#Configuration
public class JacksonConfiguration implements InitializingBean {
#Autowired private ObjectMapper objectMapper;
#Bean
public Jackson2ObjectMapperBuilder jackson2ObjectMapperBuilder(ApplicationContext context) {
Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();
builder.findModulesViaServiceLoader(true);
return builder;
}
#Override
public void afterPropertiesSet() {
objectMapper.addHandler(new NullableFieldsDeserializationProblemHandler());
}
}
But the problem of this solution is that it seems I can still access an autowired ObjectMapper that doesn't have yet registered the problem handler (I can see it happening after when I need it in debug mode).
Any idea how I should register this handler? I've noticed Jackson2ObjectMapperBuilder has a .handlerInstantiator() but I couldn't figure out how to use it.
Note I've also tried with Jackson2ObjectMapperBuilderCustomizer since I'm using Spring Boot but had no better results.
It's not possible to directly add a DeserializationProblemHandler to the ObjectMapper via a Jackson2ObjectMapperBuilder or Jackson2ObjectMapperBuilderCustomizer. The handlerInstanciator() method is for something else.
However, it's possible to do so by registering a Jackson module:
the builder has a modules() method
the module has access via setupModule() to a SetupContext instance, which has a addDeserializationProblemHandler() method
This works:
#Bean
public Jackson2ObjectMapperBuilderCustomizer customizer() {
return new Jackson2ObjectMapperBuilderCustomizer() {
#Override
public void customize(Jackson2ObjectMapperBuilder builder) {
builder.modules(new MyModule());
}
};
}
private static class MyModule extends SimpleModule {
#Override
public void setupModule(SetupContext context) {
// Required, as documented in the Javadoc of SimpleModule
super.setupModule(context);
context.addDeserializationProblemHandler(new NullableFieldsDeserializationProblemHandler());
}
}
What about writing a bean like this:
#Configuration
public class ObjectMapperConfiguration {
#Bean
ObjectMapper objectMapper() {
ObjectMapper objectMapper = new ObjectMapper();
// jackson 1.9 and before
objectMapper.configure(DeserializationConfig.Feature.FAIL_ON_UNKNOWN_PROPERTIES, false);
// or jackson 2.0
objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
return objectMapper;
}
}
This is for global configuration. If, instead, what you want to do is to configure the feature for specific a class, use this annotation above the class definition:
#JsonIgnoreProperties(ignoreUnknown = true)
I have an application with 2 Contexts. Parent for web agnostic business logic and ChildContext (implicitly created by dispatcher servlet) for web logic.
My setup loks like
#Configuration
public class BusinessConfig {
#Bean
public ObjectMapper jacksonMapper() { return new ObjectMapper() }
}
and
#Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
#Autowired
private ObjectMapper objectMapper; // <- is null for some reason
#Override
public configureMessageConverters(List<HttpMessageConverter<?>> converters) {
MappingJackson2HttpMessageConverter converter = new MappingJackson2HttpMessageConverter();
converter.setObjectMapper(objectMapper); // <- bang!
messageConverters.add(converter);
}
}
I need the the object mapper in the parent context, as I use it also in security configuration. But can someone explain me, why the #Autowired objectMapper is null? Its created in the parent context (the fact that the parent exists is even logged by spring at startup). Also #Autowired has required=true by default, so it should not blow up in the configure method (it should have blown up in construction of the context, if the bean wasn't there for some reason).
It seems to me that there might be some lifecycle problem in spring - in a sense that it calls the overridden methods first, and then #Autowires the dependencies... I have also tried to #Autowire the BusinessConfig (should be perfectly legal according to documentation - the result was the same (null)).
What should I do to make this working?
Thanks in advance!
EDIT - ISSUE FOUND
I found the issue. Unfortunately it had nothing to do with WebMvcConfigurerAdapter nor #Configuration. It was caused by premature initialization of context triggered by missing static modifier for propertyPlaceholderConfigurer... I have created issue in Spring core jira (https://jira.spring.io/browse/SPR-14382)
What about simply renaming the bean declaration method to match with the autowired bean?
#Configuration
public class BusinessConfig {
#Bean
public ObjectMapper objectMapper() { return new ObjectMapper() }
}
#Configuration
public class WebConfig extends WebMvcConfigurerAdapter {
#Autowired
private ObjectMapper objectMapper;
[...]
}