Spring MVC and JSON, Jackson class not found exception - json

Question

I cant get Spring's JSON support working. In my spring-servlet.xml file i have included following lines:
<mvc:annotation-driven/>
<context:component-scan base-package="my.packagename.here" />
<context:annotation-config />
<bean id="viewResolver"
class="org.springframework.web.servlet.view.InternalResourceViewResolver"
p:prefix="/WEB-INF/jsp/" p:suffix=".jsp" />
<bean id="jacksonMessageConverter"
class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"/>
I have also downloaded jackson libraries and added them to my eclipse project and also to WEB-INF/lib folder. When sending request to controller with jQuery getJSON method i get following errors:
javax.servlet.ServletException: Servlet.init() for servlet dispatcher threw exception
java.lang.NoClassDefFoundError: org/codehaus/jackson/JsonProcessingException
java.lang.ClassNotFoundException: org.codehaus.jackson.JsonProcessingException
What do you think is the problem. I'm guessing it has something to do with my spring-servlet.xml file. I can paste entire error log, if you need.

Answer 1

For Jackson v2 jars, class to be used for bean should be
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" />
For older jackson version, org.springframework.http.converter.json.MappingJacksonHttpMessageConverter is ok. Make sure the jar files are added to the project library.

Answer 2

The answer of anshul tiwari partially captures the problem. Here is a more complete answer ...
When Jackson made it to version 2.0, the core library got changed from jackson-core-asl-x.x.x.jar to jackson-core-x.x.x.jar. With that, the paths changed. In version 1, org.codehaus.jackson was the path. In version 2, it is in com.fasterxml.jackson.core if you were to open up the jar file.
Now if you have the libraries of version 2 and you are seeing the org.codehaus.jackson ClassNotFoundException, it means that there is a mixing of versions. Some code is expecting v1 but you have provided v2. This is certainly possible when using Spring so you have to be careful to choose the correct jar file for your code.
EDIT
In fact, looking at 3.2 Spring source code, org.springframework.http.converter.json.MappingJacksonHttpMessageConverter still references the org.codehaus stuff so this is a case where Spring source code needs to import the correct path and there is nothing you the developer can do to use jackson 2.

Answer 3

JsonProcessingException is part of the jackson-core-asl-x.x.x.jar. Make sure that it's part of your classpath.

Answer 4

Just to complement anshul tiwari answer, the bean tag should go inside mvc:annotation-driver:
<mvc:annotation-driven>
<mvc:message-converters>
<bean
class="org.springframework.http.converter.ResourceHttpMessageConverter" />
<!-- <bean -->
<!-- class="org.springframework.http.converter.xml.Jaxb2RootElementHttpMessageConverter"
/> -->
<bean
class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter" />
<!-- <bean -->
<!-- class="org.springframework.http.converter.json.MappingJacksonHttpMessageConverter"
/> -->
</mvc:message-converters>
</mvc:annotation-driven>

Answer 5

Use it Like below : Hope it will work..
http://www.springframework.org/schema/mvc/spring-mvc-4.1.xsd"
default-lazy-init="true">
<context:component-scan base-package="com.vc.bmp.resource" />
<mvc:annotation-driven>
<mvc:message-converters>
<bean class="org.springframework.http.converter.json.MappingJackson2HttpMessageConverter">
<!-- property name="prefixJson" value="true" />
<property name="supportedMediaTypes" value="application/json" /-->
<property name="objectMapper">
<bean class="com.fasterxml.jackson.databind.ObjectMapper">
<property name="serializationInclusion">
<value type="com.fasterxml.jackson.annotation.JsonInclude.Include">NON_NULL</value>
</property>
</bean>
</property>
</bean>
</mvc:message-converters>
</mvc:annotation-driven>