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not-in-svn - Inbound JCA example Java EE sample applications singletonejb-javaee6 - A simple JSF+Singleton+ejb injection application

Application Overview

This sample application demonstrates a simple order system which can get, delete, and edit resources using RESTful Web services. This web service is exposed as a Servlet in the Geronimo application server. See RESTful Web services for more information on the concept.

Application contents

The restfulorder-javaee6 application is deployed as a WAR to the application server. The overview of the structural content of the WAR file is given as follows.

|-restfulorder-javaee6.war
   +-rest
	+- restfulorder
   +-WEB-INF
	+- web.xml
        +- classes
               +- org.apache.geronimo.samples.javaee6.restfulorder
               +- META-INF
   +-META-INF

The org.apache.geronimo.samples.javaee6.restfulorder package consists of the following files.

+- org.apache.geronimo.samples.javaee6.restfulorder
   +-service
	+- RestfulordersResource.class
	+- RestfulorderResource.class
   +-config
	+- ApplicationConfig.class
   +-converter
	+- RestfulorderConverter.class
	+- RestfulordersConverter.class
   +-entities
   +-JPASessionBeans

where,

  • The service folder contains the resource classes of the RESTful application.
  • The config folder contains the servlet class that extends javax.ws.rs.core.Application to configure the application classes within a JAX-RS runtime. The javax.ws.rs.core.Application class provides methods that can specify a set of root resources and providers accessible from a specified application path. This way users can specify several groups of resources in a single application.
  • The converter folder contains Java Architecture for XML Binding annotated classes to support the processing of XML in requests and responses.

Application implementation

RestfulordersResource is a resource class that uses JAX-RS annotations to implement the corresponding Web resource.

RestfulordersResource.java
package org.apache.geronimo.samples.javaee6.restfulorder.service;

import java.util.Collection;
import javax.ws.rs.Path;
import javax.ws.rs.GET;
import javax.ws.rs.POST;
import javax.ws.rs.Produces;
import javax.ws.rs.Consumes;
import javax.ws.rs.PathParam;
import javax.ws.rs.QueryParam;
import javax.ws.rs.DefaultValue;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.UriInfo;
import javax.persistence.EntityManager;
import org.apache.geronimo.samples.javaee6.restfulorder.converter.RestfulordersConverter;
import org.apache.geronimo.samples.javaee6.restfulorder.converter.RestfulorderConverter;
import javax.persistence.PersistenceContext;
import javax.ejb.Stateless;
import org.apache.geronimo.samples.javaee6.restfulorder.entities.Restfulorder;


@Path("/restfulorders/")
@Stateless
public class RestfulordersResource {
    @javax.ejb.EJB
    private RestfulorderResource restfulorderResource;
    @Context
    protected UriInfo uriInfo;
    @PersistenceContext(unitName = "RestfulProduct2PU")
    protected EntityManager em;
  
    /** Creates a new instance of RestfulordersResource */
    public RestfulordersResource() {
    }

    /**
     * Get method for retrieving a collection of Restfulorder instance in XML format.
     *
     * @return an instance of RestfulordersConverter
     */
    @GET
    @Produces({"application/xml", "application/json"})
    public RestfulordersConverter get(@QueryParam("start")
                                      @DefaultValue("0")
    int start, @QueryParam("max")
               @DefaultValue("10")
    int max, @QueryParam("expandLevel")
             @DefaultValue("1")
    int expandLevel, @QueryParam("query")
                     @DefaultValue("SELECT e FROM Restfulorder e")
    String query) {
        return new RestfulordersConverter(getEntities(start, max, query), uriInfo.getAbsolutePath(), expandLevel);
    }

    /**
     * Post method for creating an instance of Restfulorder using XML as the input format.
     *
     * @param data an RestfulorderConverter entity that is deserialized from an XML stream
     * @return an instance of RestfulorderConverter
     */
    @POST
    @Consumes({"application/xml", "application/json"})
    public Response post(RestfulorderConverter data) {
        System.out.println("before resolve,in post");
        Restfulorder entity = data.resolveEntity(em);
        createEntity(data.resolveEntity(em));
        return Response.created(uriInfo.getAbsolutePath().resolve(entity.getId() + "/")).build();
    }

    /**
     * Returns a dynamic instance of RestfulorderResource used for entity navigation.
     *
     * @return an instance of RestfulorderResource
     */
    @Path("{id}/")
    public RestfulorderResource getRestfulorderResource(@PathParam("id")
    Integer id) {
        restfulorderResource.setId(id);
        restfulorderResource.setEm(em);
        return restfulorderResource;
    }

    /**
     * Returns all the entities associated with this resource.
     *
     * @return a collection of Restfulorder instances
     */
    protected Collection<Restfulorder> getEntities(int start, int max, String query) {
        return em.createQuery(query).setFirstResult(start).setMaxResults(max).getResultList();
    }

    /**
     * Persist the given entity.
     *
     * @param entity the entity to persist
     */
    protected void createEntity(Restfulorder entity) {
        em.persist(entity);
    }
}

where,

  • @Path("/restfulorders/") is the annotation that defines the relative URI to your resource. The base URI is provided by the combination of your hostname, port, application context root, and any URI pattern mappings in the application's web.xml file. For example, the URI for the resource presented by this resource class can be http://localhost:8080/restfulorder-javaee6/resources/restfulorders/.
  • @Path("{id}/") annotates a sub-resource locator which returns a RestfulorderResource object to handle HTTP requests. The id parameter in this annotation defines the relative URI under /restfulorders to the resource.
  • @Context is used in this resource class to inject an instance of UriInfo into the class field.
  • UriInfo instances can provide information on the components of a request URI.
  • @GET and @POST are request method designators for annotating resource methods in a resource class. Other common request method designators include @PUT, @DELETE, and @HEAD.
  • @Consumes and @Produces annotations are used to declare the supported request and response media types. In this resource class, the post and get methods both support application/xml and application/json.

ApplicationConfig is a servlet that extends the javax.ws.rs.core.Application class to configure the application classes within a JAX-RS runtime.

ApplicationConfig.java
package org.apache.geronimo.samples.javaee6.restfulorder.config;

@javax.ws.rs.ApplicationPath("resources")
public class ApplicationConfig extends javax.ws.rs.core.Application {
}

where,

  • @javax.ws.rs.ApplicationPath is an annotation that helps to specify the resource path of the application. The value of this annotation is used as the servlet URL pattern. For example, the URI for the resource presented in this application can be http://localhost:8080/restfulorder-javaee6/resources/restfulorders/. You can also specify this URL patterns in your web.xml file if this annotation is absent.
  • javax.ws.rs.core.Application is a class that contains the getClasses and getSingletons methods that can specify a set of root resources and providers accessible from a specified application path respectively. The ApplicationConfig class uses the default implementations of javax.ws.rs.core.Application subclass getClasses and getSingletons methods that return empty sets. In this case, when both methods return an empty list, all root resource classes and providers packaged in the application are included in the published JAX-RS
    application.
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