How to insert data from database with Web Service in java using JAX - RS

Question

I am new to web services. Please give suggestions how to insert and retrieve data from database using jersey JAX - RS in java?

Answer 1

Have a look at this link, there is a video tutorial that explains one way how it can be done.

So the video is explaining how a web service retrieves some value to tell the client that the given credentials match against some data in a database.

This is how the method that handle the client request looks like:

@POST
    @Produces(MediaType.TEXT_PLAIN)
    @Path("/login")
    public Response login(@FormParam("email") String email, @FormParam("password") String password) {

        Response.ResponseBuilder responseBuilder = null;
        
        boolean result = entityFacade.doLogin(email, password);
        if (result) {
             responseBuilder = Response.ok("Success");//Login good!
        }
        else {            
            responseBuilder = Response.ok("Wrong credentials!");//Login bad!
        }

        return responseBuilder.build();
    }

This Web service transfers the credentials to the business layer where an EJB will perform a select operation in the database:

@Stateless
public class EntityFacade implements EntityFacadeLocal {

    @Resource
    private UserTransaction ut;
    private CredentialJpaController controller;

    @PostConstruct
    public void init() {        
        controller = new CredentialJpaController(ut, Persistence.createEntityManagerFactory("ROLEProject-ejbPU"));
    }


    public boolean doLogin(String email, String password){        
        return controller.loginWithParameters(email,password);
    }
}

The EJB relies in a service class that will do the task of interact with the database

public class CredentialJpaController implements Serializable {

    public CredentialJpaController(UserTransaction utx, EntityManagerFactory emf) {
        this.utx = utx;
        this.emf = emf;
    }
    private UserTransaction utx = null;
    private EntityManagerFactory emf = null;

    public EntityManager getEntityManager() {
        return emf.createEntityManager();
    }
    public boolean loginWithParameters(String email, String password) {
        boolean result = false;
        EntityManager em = getEntityManager();
        Long l = (Long) em.createNamedQuery("loginquery").setParameter("emailParam", email).setParameter("passwordParam", password).getSingleResult();
        if (l == 1) {
            result = true;
        }
        return result;
    }
}

Finally to be able to interact with the DB, the data must be represented as a JPA entity. Also to be able to marshal the selected row back to the client as whatever MediaType is desired, the entity must contain some JaxB annotations:

@XmlRootElement
@Entity
@Table(name = "CREDENTIALS")
@NamedQuery(name="loginquery", query="SELECT COUNT(c) FROM Credential c WHERE c.email = :emailParam AND c.password = :passwordParam")
public class Credential implements Serializable {

    @Id
    private String email;
    @Column(nullable = false)
    private String password;

    @XmlElement
    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

     @XmlElement
    public String getPassword() {
        return password;
    }

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

Here is some sample client code so you can see one of the ways how the web-service can be called:

    
        
    
    
        
TODO write content
        

            Email 
            Password 
            
        
    

I hope this helps to give you an idea.

To do insert data the process is almost the same, just use the method persist() instead of find() from the entity manager.