[FIXED] JAX-RS on Tomcat by using RestEasy

Issue

I'm new to the REST application by using the JAX-RS standard and I want to learn how to work with this standard. So I downloaded and setup Apache Tomcat 9.0 and I added the <Context> like this:

<Context docBase="...\RestEasyApp\target\RestEasyApp" path="/example" reloadable="true"/>

Then with Maven I created my project that have this structure:

Then into the pom.xml i added RestEasy by this dependencies:

<!-- https://mvnrepository.com/artifact/org.jboss.resteasy/resteasy-jaxrs -->
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-jaxrs</artifactId>
    <version>3.5.1.Final</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.jboss.resteasy/resteasy-servlet-initializer -->
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-servlet-initializer</artifactId>
    <version>3.5.1.Final</version>
</dependency>

<!-- https://mvnrepository.com/artifact/org.jboss.resteasy/resteasy-jackson2-provider -->
<dependency>
    <groupId>org.jboss.resteasy</groupId>
    <artifactId>resteasy-jackson2-provider</artifactId>
    <version>3.5.1.Final</version>
</dependency>

Then into the web.xml I created the Servlet and it looks like this:

<web-app>
    <listener>
      <listener-class>
         org.jboss.resteasy.plugins.server.servlet.ResteasyBootstrap
      </listener-class>
   </listener>

  <display-name>Archetype Created Web Application</display-name>
  <servlet>
      <servlet-name>Resteasy</servlet-name>
        <servlet-class>
            org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher
        </servlet-class>
  </servlet>

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

</web-app>

Then finally i created the Hello.java class that will handle the request and it looks like this:

package com.pisi.resteasyapp;

import javax.ws.rs.*;

@Path("/api")
class Hello {

    @GET
    @Path("/hello")
    public String hello() {
        return "HELLO";
    }

}

But when I run this App with this uri http://localhost:8080/example/rest/api/hello , it gives me this:

I have no clue why it wont work.

Solution

You must add an Application class to your project:

package com.pisi.resteasyapp;

import java.util.HashSet;
import java.util.Set;

import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;

@ApplicationPath("")
public class HelloApplication extends Application {

    @Override
    public Set<Object> getSingletons() {
        Set<Object> set = new HashSet<>();
        set.add(new Hello());
        return set;
    }

}

You have also to change the mapping of the Helloclass from @Path("/api") to @Path("/rest/api") and make the class public to allow RESTEasy to reflect on the hello() method:

@Path("/rest/api")
public class Hello {

In general, a better solution would be:

1. remove the <servlet-mapping> from web.xml
2. change @ApplicationPath("") to @ApplicationPath("/rest") in the HelloApplication class
3. use @Path("/api") instead of @Path("/rest/api") in the Hello class

Answered By - Robert Hume