Java Jersey Rest : No provider classes found. (404 error when accessing URL)

Question

Edit: I hadn't realized that all request were first going into "Apache" and then were redirected to Tomcat. I added a new redirection in the apache2.conf file. See the accepted answer for details.

I am having the exact same problem as this question. Jersey REST The ResourceConfig instance does not contain any root resource classes However the user never answered the question.

I am using Tomcat, without maven. I followed this tutorial. http://www.ibm.com/developerworks/web/library/wa-aj-tomcat/index.html

I made changes to web.xml as per the article
i.e the new servlet and servlet mapping was created with the correct package name.

<servlet>
  <servlet-name>Jersey REST Service</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>sample.hello.resources</param-value>
  </init-param>
  <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
  <servlet-name>Jersey REST Service</servlet-name>
  <url-pattern>/rest/*</url-pattern>
</servlet-mapping>

I have deployed the following jars to tomcat

asm.jar
jersey-server.jar
jersey-core.jar
jsr311.jar

The tomcat startup log has the following exceptions.

    com.sun.jersey.api.core.PackagesResourceConfig init
    INFO: Scanning for root resource and provider classes in the packages:
      sample.hello.resources

   com.sun.jersey.api.core.ScanningResourceConfig logClasses
    INFO: Root resource classes found:
      class sample.hello.resources.HelloResource

   com.sun.jersey.api.core.ScanningResourceConfig init
    INFO: No provider classes found.

   com.sun.jersey.server.impl.application.WebApplicationImpl _initiate
    INFO: Initiating Jersey application, version 'Jersey: 1.8 06/24/2011 12:17 PM'

When I access the URL I get a 404. http://localhost:8080/Jersey/rest/hello

The code:

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

@Path("/hello")
public class HelloResource {
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String sayHello() {
        return "Hello Jersey";
    }
}

I do not see any other exceptions in the logs

It would help if you posted the web.xml and the sample.hello.resources.HelloResource class as well. — gnuf
Those don't look like exceptions to me in your log, just informational messages. That IBM tutorial says something about creating a web app named Jersey using Eclipse. I'm not familiar with deploying to Tomcat via Eclipse, but are you certain that Jersey is the right deployment path? That is, have you tried browsing to localhost:8080/rest/hello ? — gnuf
The context path is without changing it like the Eclipse project name. You can investigate this easily by drill down the projects tree of you Tomcat in your Eclipse Server view. But it is possible to change the context path in your project properties at the Web Project Settings tab. However the path should be "localhost:port/[Eclipse project name]/rest/hello — Omnaest
shouldn't the @Path be "/rest/hello"? I never know, and just map the servlet to /* :-) — Szocske
I don't think the "No provider classes found" is a fatal problem, or related to the 404 for the actual API requests. — metamatt

Szocske Szocske · Accepted Answer · 2011-07-05T21:04:31

Verify you have the right URL:

The tomcat manager application is happy to direct you to the root URL of the servlet. (you are assuming this is "Jersey" with capital J.) http://localhost:8080/manager/html/list

Then you can skip the "rest" part by setting the URL pattern in the servlet mapping of the web.xml to "/*" (yes, there was a bug in Jersey related to that once, but that's ancient history)

Then you can append "application.wadl" to get a description of available resources. Theoretically: http://localhost:8080/Jersey/application.wadl

Java Jersey Rest : No provider classes found. (404 error when accessing URL)

3 Answers