No Idea why : The ResourceConfig instance does not

Question

This question already has answers here:

The ResourceConfig instance does not contain any root resource classes (25 answers)

Closed 2 years ago.

I'm new to jersey and web services and I'm try to run a simple RESTful web service. I followed http://www.mkyong.com/webservices/jax-rs/jersey-hello-world-example/ but my project doesn't use maven and I download the jersey.1.17.1.jar and include it to my project path.

When I want to call the service on http://localhost:8080/sycotext/rest/service/SOMETEXT I get this error :

HTTP Status 500 - Servlet.init() for servlet sycoText-servlet threw exception

this is the stack trace :

javax.servlet.ServletException: Servlet.init() for servlet sycoText-servlet threw exception
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:76)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:934)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:515)
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1010)
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:640)
    org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1618)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1576)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    java.lang.Thread.run(Thread.java:724)

root cause

com.sun.jersey.api.container.ContainerException: The ResourceConfig instance does not contain any root resource classes.
    com.sun.jersey.server.impl.application.RootResourceUriRules.<init>(RootResourceUriRules.java:99)
    com.sun.jersey.server.impl.application.WebApplicationImpl._initiate(WebApplicationImpl.java:1331)
    com.sun.jersey.server.impl.application.WebApplicationImpl.access$700(WebApplicationImpl.java:168)
    com.sun.jersey.server.impl.application.WebApplicationImpl$13.f(WebApplicationImpl.java:774)
    com.sun.jersey.server.impl.application.WebApplicationImpl$13.f(WebApplicationImpl.java:770)
    com.sun.jersey.spi.inject.Errors.processWithErrors(Errors.java:193)
    com.sun.jersey.server.impl.application.WebApplicationImpl.initiate(WebApplicationImpl.java:770)
    com.sun.jersey.server.impl.application.WebApplicationImpl.initiate(WebApplicationImpl.java:765)
    com.sun.jersey.spi.container.servlet.ServletContainer.initiate(ServletContainer.java:489)
    com.sun.jersey.spi.container.servlet.ServletContainer$InternalWebComponent.initiate(ServletContainer.java:319)
    com.sun.jersey.spi.container.servlet.WebComponent.load(WebComponent.java:605)
    com.sun.jersey.spi.container.servlet.WebComponent.init(WebComponent.java:210)
    com.sun.jersey.spi.container.servlet.ServletContainer.init(ServletContainer.java:374)
    com.sun.jersey.spi.container.servlet.ServletContainer.init(ServletContainer.java:557)
    javax.servlet.GenericServlet.init(GenericServlet.java:160)
    org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:504)
    org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:76)
    org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:934)
    org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:515)
    org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1010)
    org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:640)
    org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1618)
    org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1576)
    java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    java.lang.Thread.run(Thread.java:724)

here is my code :

package ir.sycotech.text.server.service;

import javax.ws.rs.*;
import javax.ws.rs.core.Response;

@Path("/service")
public class SycoTextService {
    @GET
    @Path("/{param}")
    public Response getMsg(@PathParam("param") String msg) {
        String output = "Jersey say : " + msg;
        return Response.status(200).entity(output).build();
   }

and here is my web.xml :

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4"
         xmlns="http://java.sun.com/xml/ns/j2ee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
    http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

    <display-name>Restful Web Application</display-name>


    <servlet>
        <servlet-name>sycoText-servlet</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>ir.sycotech.text.server.service</param-value>
        </init-param>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>sycoText-servlet</servlet-name>
        <url-pattern>/rest/*</url-pattern>
    </servlet-mapping>

</web-app>

I have specified my packagename correctly in the web.xml file and I don't know why I got this error, I will be really appreciate if anyone knows what is the problem

Answer 1

I ran into this issue, as well. There were two things that I did to get it to work, with the first being unrelated to this problem.

First, I'm using jersey 1.19. However, I didn't realize there was a file named javax.ws.rs-api-2.0.jar in the WEB-INF/lib on the server. This file was added two years ago and, IIRC, works in conjunction with jersey 2.x but not 1.x. I effectively removed the file (renamed it with .bak as its extension).

Second, I created a JAR file in Eclipse for the web service. I did not use Maven or Ant or anything like that. Just a simple export. Now, the error can mean there is nothing in your code that references jersey. But I wrote a simple test class and everything should be working, I thought. Turns out the export wasn't creating the JAR file properly. I opened the JAR and the class was empty. No wonder it was generating this error! I exported once more and instead of checkmarking Export generated class files and resources, I checkmarked Export all output folders for checked projects. I also have multiple packages in this one project so that could be related to why the export wasn't functioning properly. Once I did that, it worked!

I tried the export again but, this time, I checkmarked Export generated class files and resources and selected every resource in the project. What was different from last time was I selected .settings. Last time, .settings wasn't selected. Again, this worked, too!

I hope this helps someone out there with a similar problem. Sometimes, it's just something as stupid as confirming your JAR file is correct. I use java decompiler to inspect the JAR file.

Answer 2

I had the same problem, which I solved by specifying BOTH the classes package AND removing load-on-startup altogether, i.e.:

<servlet>
    <servlet-name>my-servlet-name</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>my.package.name</param-value>
    </init-param>
    <!-- <load-on-startup>1</load-on-startup> -->
</servlet>

I guess because I had more than one servlet under the same package and Jersey coudn't pick the "root" one to be loaded on startup.

Answer 3

Well, none of the above answers worked for me. They made me double check every step and package name, though. As Bogdan said, there were no compiled classes inside the target/classes/ folder.

Check that your application deployed correctly and that your WEB-INF/classes folder actually contains your class with the proper folder path for the package.

My solution was just cleaning the project and compiling different. Instead of just going for mvn war:war I did:

$ mvn clean:clean $ mvn compile $ mvn war:war

Then it compiled fine and the OP error disappeared.