Illegal to inject a message body into a singleton into public org.codehaus.jackson.jaxrs.JacksonJsonProvider

Problem

Using Jackson as JSON provider in RESTEasy.

	<dependency>
		<groupId>org.jboss.resteasy</groupId>
		<artifactId>resteasy-jaxrs</artifactId>
		<version>2.2.1.GA</version>
	</dependency>

	<dependency>
		<groupId>org.jboss.resteasy</groupId>
		<artifactId>resteasy-jackson-provider</artifactId>
		<version>2.2.1.GA</version>
	</dependency>

With RESTEasy auto scanning enabled.

	<context-param>
		<param-name>resteasy.scan</param-name>
		<param-value>true</param-value>
	</context-param>

When starting up, it hits following errors and failed to start up any of the RESTEasy services.

SEVERE: Exception sending context initialized event to listener instance of class 
	org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
java.lang.RuntimeException: Unable to instantiate MessageBodyReader
	at org.jboss.resteasy.spi.ResteasyDeployment.registerProvider(ResteasyDeployment.java:505)
	at org.jboss.resteasy.spi.ResteasyDeployment.registration(ResteasyDeployment.java:305)
	at org.jboss.resteasy.spi.ResteasyDeployment.start(ResteasyDeployment.java:225)
	//...
Caused by: java.lang.RuntimeException: 
        Illegal to inject a message body into a singleton into public
	org.codehaus.jackson.jaxrs.JacksonJsonProvider(
	org.codehaus.jackson.map.ObjectMapper,org.codehaus.jackson.jaxrs.Annotations[])
	... 20 more

Solution

There is problem to integrate RESTEasy with Jackson if “auto scanning” mode is enabled. Hope it will fixed in later released.

To fix it, disabled the auto scanning feature, and register your RESTEasy service manually in web.xml.

	<!-- disabled auto scanning
	<context-param>
		<param-name>resteasy.scan</param-name>
		<param-value>true</param-value>
	</context-param>
        -->
	<context-param>
		<param-name>resteasy.resources</param-name>
		<param-value>com.mkyong.JacksonRestServiceHere</param-value>
	</context-param>