JAX-RS-JPA-CRUD

This project is no longer being maintained (however, the released artifacts will still remain in Maven Central). JAX-RS is simply not created to be extendable/composable (eg. it is impossible to overload a JAX-RS method with different @QueryParams).

Provides extendable classes/interfaces to create JAX-RS CRUD Web Services from JPA entity classes.

The generated JAX-RS Web Services will contain:

• A POST method to insert a row
• A GET method to query all rows
• A /{id} GET method to query a row by id
• A /{from}/{to} GET method to query rows within the given range of ids
• A /count GET method to query the number of rows
• A PUT method to update a row
• A /{id} DELETE method to delete a row

Requirements

Dependency	Version
JPA	2.X.X
JAX-RS	2.X
JTA	1.2

The easiest way to provide the implementation for all the dependencies is to use a Java EE container (eg. WildFly).

Version 3.0.0+ no longer depends on Java EE or CDI (Contexts and Dependency Injection). You can now use this outside of a Java EE container, as long as a JPA, JAX-RS and JTA implementation is provided (eg. Hibernate + Jersey + Narayana).

Usage

Add the following to your Maven dependency list:

<dependency>
    <groupId>com.github.daniel-shuy</groupId>
    <artifactId>jax-rs-jpa-crud</artifactId>
    <version>4.0.0</version>
</dependency>

All CRUD database tables must have a sequential number Surrogate Primary Key.

For each CRUD database table:

• Create a JPA Entity Class that extends com.github.daniel.shuy.ws.rs.jpa.crud.EntityCRUD, without a field for the Primary Key (already mapped in EntityCRUD).
• Create a Repository Class that implements com.github.daniel.shuy.ws.rs.jpa.crud.RepositoryCRUD
• Create a JAX-RS Resource Class that implements com.github.daniel.shuy.ws.rs.jpa.crud.ResourceCRUD.

Resource/Repository Classes can be further customized/extended by implementing additional methods.

Example:

Entity Class:

@Entity
@Table(name = "user")
@XmlRootElement
public class User extends EntityCRUD {
    private static final long serialVersionUID = 1L;

    @Column(name = "username")
    private String username;

    @Column(name = "password")
    private String password;

    public User() {
    }

    public User(Long id) {
        super(id);
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }
}

Repository Class

• Override getEntityClass to provide the JPA Entity Class.
• Override getEntityManager to provide the JPA EntityManager instance to use. How to provide the EntityManager instance depends on your environment.

CDI Example (Recommended)

• Requires Contexts and Dependency Injection (CDI)

@RequestScoped
public class UserRepository implements RepositoryCRUD<User> {
    @PersistenceContext(name = "persistence-unit")  // name is Persistence Unit Name configured in persistence.xml
    private EntityManager entityManager;

    @Override
    public EntityManager getEntityManager() {
        return entityManager;
    }

    @Override
    public Class<User> getEntityClass() {
        return User.class;
    }
}

EJB Example

• Requires Repository Class to be an Enterprise JavaBean (EJB)

@Stateless
@LocalBean
public class UserRepository implements RepositoryCRUD<User> {
    @PersistenceContext(name = "persistence-unit")  // name is Persistence Unit Name configured in persistence.xml
    private EntityManager entityManager;

    @Override
    public EntityManager getEntityManager() {
        return entityManager;
    }

    @Override
    public Class<User> getEntityClass() {
        return User.class;
    }
}

Barebones (no CDI/EJB) Example

• A new EntityManager instance needs to be created for each RepositoryCRUD instance, because EntityManager is not thread-safe.

public class UserRepository implements RepositoryCRUD<User> {
    // argument is Persistence Unit Name configured in persistence.xml
    private static final EntityManagerFactory factory = Persistence.createEntityManagerFactory("persistence-unit");

    private final EntityManager entityManager;

    public UserRepository() {
        entityManager = factory.createEntityManager();
    }

    @Override
    public EntityManager getEntityManager() {
        return entityManager;
    }

    @Override
    public Class<User> getEntityClass() {
        return User.class;
    }
}

Resource Class

CDI Example:

@Path("/user")
public class UserResource extends ResourceCRUD<User> {
    @Inject
    private UserRepository repository;

    @Override
    public RepositoryCRUD<User> getRepository() {
        return repository;
    }
}

EJB Example:

@Path("/user")
public class UserResource extends ResourceCRUD<User> {
    @EJB
    private UserRepository repository;

    @Override
    public RepositoryCRUD<User> getRepository() {
        return repository;
    }
}

Barebones (no CDI/EJB) Example:

• A new RepositoryCRUD instance needs to be explicitly created on each call to getRepository(), since we don't have CDI's @RequestScoped or EJB's @Stateless.

@Path("/user")
public class UserResource extends ResourceCRUD<User> {
    @Override
    public RepositoryCRUD<User> getRepository() {
        return new UserRepository();
    }
}