JAX-RS JUG Demo CDI and @Singleton Usage

Thursday, July 26, 2012

JAX-RS JUG Demo CDI and @Singleton Usage

This is the last demonstration I gave at the Greenville Java Users Group (GreenJUG) on CDI and JAX-RS. I cleaned up the code, but not as much as you would think. I managed to code this in about 15 minutes during the meeting live while everyone watched. It was a fun experience, but the best part is that it worked during a live un-rehearsed demo.

It goes to show you that CDI and JAX-RS are simple enough in combination to use in a live high stress demo environment. Imagine what it could do for you in your code. This code was written using NetBeans 7 IDE which may be responsible for the simplicity as much as the other technologies.

Here is the source code: cdi-example.zip

The code below demonstrates some interesting bits. The source code above contains the less interesting POJOs.

PersonResource.java

package com.bluelotussoftware.example;
 
import java.util.List;
import javax.annotation.ManagedBean;
import javax.inject.Inject;
import javax.ws.rs.*;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.Response;
 
/**
 * REST resource for {@link com.bluelotussoftware.example.Person} objects.
 *
 * @author John Yeary
 * @version 1.0
 */
@Path("person")
@ManagedBean
public class PersonResource {
 
    @Inject
    private PersonDB pdb;
 
    @GET
    @Produces({MediaType.APPLICATION_JSON})
    public List<person> getPersons() {
        return pdb.getPersons();
    }
 
    @GET
    @Path("{index}")
    @Produces({MediaType.APPLICATION_JSON})
    public Person getPerson(@PathParam("index") int index) {
        try {
            return pdb.getPersons().get(index);
        } catch (IndexOutOfBoundsException e) {
            throw new WebApplicationException(e, Response.Status.NOT_FOUND);
        }
    }
 
    @GET
    @Path("{index}/phones")
    @Produces({MediaType.APPLICATION_JSON})
    public List<phone> getPhones(@PathParam("index") int index) {
        return pdb.getPersons().get(index).getPhoneNumbers();
    }
 
    @GET
    @Path("{index}/phones/{location}")
    @Produces({MediaType.APPLICATION_JSON})
    public Phone getPhone(@PathParam("index") int index, @PathParam("location") String location) {
        try {
            List<phone> phones = pdb.getPersons().get(index).getPhoneNumbers();
            for (Phone p : phones) {
                if (location != null && location.equals(p.getLocation())) {
                    return p;
                }
            }
            return new Phone();
        } catch (IndexOutOfBoundsException e) {
            throw new WebApplicationException(e, Response.Status.NOT_FOUND);
        }
    }
}

PersonDB.java

package com.bluelotussoftware.example;
 
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.List;
import javax.annotation.PostConstruct;
import javax.inject.Singleton;
 
/**
 * A {@code @Singleton} database of {@link com.bluelotussoftware.example.Person}
 * objects.
 *
 * @author John Yeary
 * @version 1.0
 */
@Singleton
public class PersonDB implements Serializable {
 
    private static final long serialVersionUID = 2500854255025449263L;
    private List<person> persons;
 
    public PersonDB() {
        persons = new ArrayList<person>();
    }
 
    @PostConstruct
    private void init() {
        List<phone> phones = new ArrayList<phone>();
        phones.add(new Phone("Home", "111-222-3333"));
        phones.add(new Phone("Mobile", "999-111-2222"));
        phones.add(new Phone("Work", "888-777-6666"));
        persons.add(new Person("John", new Date(), phones));
        persons.add(new Person("Sean", new Date(), phones));
        persons.add(new Person("Ethan", new Date(), phones));
    }
 
    public List<person> getPersons() {
        return Collections.unmodifiableList(persons);
    }
 
    public boolean addPerson(Person p) {
        return persons.add(p);
    }
 
    public boolean removePerson(Person p) {
        return persons.remove(p);
    }
}

Java Evangelist John Yeary

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Thursday, July 26, 2012