Jersey REST The ResourceConfig instance does not contain any root resource classes [duplicate]

Question

Although this is one ancient question, I still can not find the answer to make this work. Please correct if you find any of my statement is not correct.

I have a Java Face app and use REST for the Web Services. I don't think Face has anything to do with my problem at all. The web.xml is:

<servlet>
    <servlet-name>NDREST</servlet-name>
    <servlet-class>
        com.sun.jersey.spi.container.servlet.ServletContainer
    </servlet-class>
    <init-param>
        <param-name>com.sun.jersey.config.property.packages</param-name>
        <param-value>com.bi.nd.webservice</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
    <servlet-name>NDREST</servlet-name>
    <url-pattern>/nd/*</url-pattern>
</servlet-mapping>

I have quite a few more servlets in the web.xml since is is a Face app with Trinidad, etc.

In the package com.bi.nd.webservice, my resource class is:

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.Marshaller;

import javax.ws.rs.Consumes;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Produces(MediaType.APPLICATION_XML)
@Path("/hello")
public class TransactionResource 
{
public TransactionResource() 
{
}

@GET
@Produces(MediaType.TEXT_PLAIN)
public String itWorks()
{
    return "Get is OK";
}
}

The fact that my class has a @GET is enough to identify itself a resource class.
Let alone all other complexities, I compiled my source code with Ant in Eclipse and I got this error in the catalina.out file:

May 24, 2011 8:48:46 AM com.sun.jersey.api.core.PackagesResourceConfig init
INFO: Scanning for root resource and provider classes in the packages:
     com.bi.nd.webservice
May 24, 2011 8:48:46 AM com.sun.jersey.server.impl.application.WebApplicationImpl _initiate
INFO: Initiating Jersey application, version 'Jersey: 1.7 05/20/2011 11:04 AM'
May 24, 2011 8:48:46 AM com.sun.jersey.server.impl.application.RootResourceUriRules <init>
SEVERE: The ResourceConfig instance does not contain any root resource classes.

Some suggested that copy the asm.jar, jsr-api.jar, jersey-server.jar and jersey-core.jar into the app WEB-INF/lib. I did that and it still did not work. I found the suggestion was a bit odd since WEB-INF/lib is a place where Eclipse will install all dependency libraries from the build path. It is not a place where we manually put libraries.

Some explained that this error had something to do with Java plug-in and the way Jersey was written. But that was years ago.

Can some one explains to me why I keep having this problem?

Followup: Although from REST web site, resource class defined as Root resource classes are POJOs (Plain Old Java Objects) that are either annotated with@Path or have at least one method annotated with @Path or a request method designator such as @GET, @PUT, @POST, or @DELETE. Resource methods are methods of a resource class annotated with a request method designator. This section describes how to use Jersey to annotate Java objects to create RESTful web services.

I have to add @Path("/hello") to my class, and suddenly Jersey can find my resource class

Now the catalina.out file looks like:

May 24, 2011 3:13:02 PM com.sun.jersey.api.core.PackagesResourceConfig init
INFO: Scanning for root resource and provider classes in the packages:
com.bi.nd.webservice
May 24, 2011 3:13:02 PM com.sun.jersey.api.core.ScanningResourceConfig logClasses
INFO: Root resource classes found:
class com.bi.nd.webservice.TransactionResource
May 24, 2011 3:13:02 PM com.sun.jersey.api.core.ScanningResourceConfig init
INFO: No provider classes found.
May 24, 2011 3:13:02 PM com.sun.jersey.server.impl.application.WebApplicationImpl _initiate
INFO: Initiating Jersey application, version 'Jersey: 1.7 05/20/2011 11:04 AM'

But the problem is far from over. I try to access the URL http://localhost:8080/nd/hello and I still get the 404 NOT FOUND. Is the Provider class NOT FOUND an important message?

Answer 1

I had the same error message and solved it by modifying my web.xml file. Make sure it has this in it:

<init-param>
   <param-name>com.sun.jersey.config.property.packages</param-name>
   <param-value>your.package.name.here</param-value>
</init-param>