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package br.com.caelum.livraria.dao;

import java.io.Serializable;

import javax.enterprise.context.RequestScoped;
import javax.enterprise.inject.Disposes;
import javax.enterprise.inject.Produces;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;

public class JPAUtil  implements Serializable{

    private static EntityManagerFactory emf = Persistence
            .createEntityManagerFactory("livraria");

    @Produces
    @RequestScoped
    public EntityManager getEntityManager() {
        return emf.createEntityManager();
    }

    public void close(@Disposes EntityManager em) {
        em.close();
    }
}


package br.com.caelum.livraria.dao;

import java.util.List;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Map;

import javax.persistence.EntityManager;
import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;

public class DAO<T> implements Serializable{

    private static final long serialVersionUID = 1L;

    private final Class<T> classe;
    private EntityManager manager;

    public DAO(EntityManager manager, Class<T> classe) {
        this.manager = manager;
        this.classe = classe;
    }

    public void adiciona(T t) {
        // persiste o objeto
        manager.persist(t);
    }

    public void remove(T t) {
        manager.remove(manager.merge(t));
    }

    public void atualiza(T t) {
        manager.merge(t);
    }

    public List<T> listaTodos() {
        CriteriaQuery<T> query = manager.getCriteriaBuilder().createQuery(classe);
        query.select(query.from(classe));

        List<T> lista = manager.createQuery(query).getResultList();

        return lista;
    }

    public T buscaPorId(Integer id) {
        T instancia = manager.find(classe, id);
        return instancia;
    }

    public int contaTodos() {
        long result = (Long) manager.createQuery("select count(n) from livro n").getSingleResult();

        return (int) result;
    }

    public List<T> listaTodosPaginada(int firstResult, int maxResults, Map<String, Object> filtros) {
        CriteriaBuilder builder = manager.getCriteriaBuilder();
        CriteriaQuery<T> query = builder.createQuery(classe);
        Root<T> root = query.from(classe);

        List<Predicate> predicates = new ArrayList<Predicate>();

        for (Map.Entry<String, Object> entry : filtros.entrySet()) {
            if (entry.getValue() != null) {
                Path<String> field = root.<String> get(entry.getKey());
                String valor = "%" + entry.getValue().toString() + "%";

                Predicate predicate = builder.like(field, valor) ;
                predicates.add(predicate);
            }
        }

        query.where((Predicate[]) predicates.toArray(new Predicate[0]));

        List<T> lista = manager.createQuery(query).setFirstResult(firstResult).setMaxResults(maxResults).getResultList();

        return lista;
    }

    public int quantidadeDeElementos() {
        long result = (Long) manager.createQuery("select count(n) from " + classe.getSimpleName() + " n").getSingleResult();

        return (int) result;
    }
}


package br.com.caelum.livraria.tx;

import java.io.Serializable;

import javax.inject.Inject;
import javax.interceptor.AroundInvoke;
import javax.interceptor.Interceptor;
import javax.interceptor.InvocationContext;
import javax.persistence.EntityManager;

@SuppressWarnings("serial")
@Transacional
@Interceptor
public class GerenciadorDeTransacao implements Serializable{

    /**
     * 
     */
    private static final long serialVersionUID = 1L;

    @Inject
    EntityManager manager;

    @AroundInvoke
    public Object executaTx(InvocationContext context) throws Exception {
        System.out.println("abrindo transacao");
        manager.getTransaction().begin();

        // chama os daos que precisam de transacao
        Object result = context.proceed();

        System.out.println("fechando transacao");
        manager.getTransaction().commit();

        return result;
    }

}


package br.com.caelum.livraria.tx;

import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import javax.interceptor.InterceptorBinding;

@InterceptorBinding
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.TYPE})
public @interface Transacional {

}


<beans>
    <interceptors>
        <class>br.com.caelum.livraria.tx.GerenciadorDeTransacao</class>
    </interceptors>
</beans>


package br.com.caelum.livraria.bean;

import java.io.Serializable;
import java.util.List;

import javax.faces.view.ViewScoped;
import javax.inject.Inject;
import javax.inject.Named;

import br.com.caelum.livraria.dao.AutorDao;
import br.com.caelum.livraria.modelo.Autor;
import br.com.caelum.livraria.tx.Transacional;

@Named
@ViewScoped
public class AutorBean implements Serializable {

    private static final long serialVersionUID = 1L;

    private Autor autor = new Autor();

    @Inject
    private AutorDao autorDao;

    private Integer autorId;

    public Integer getAutorId() {
        return autorId;
    }

    public void setAutorId(Integer autorId) {
        this.autorId = autorId;
    }

    public void carregarAutorPelaId() {
        this.autor = this.autorDao.buscaPorId(autorId);
    }

    @Transacional
    public String gravar() {
        System.out.println("Gravando autor " + this.autor.getNome());

        if(this.autor.getId() == null) {
            this.autorDao.adiciona(this.autor);
        } else {
            this.autorDao.atualiza(this.autor);
        }

        this.autor = new Autor();

        return "livro?faces-redirect=true";
    }

    @Transacional
    public void remover(Autor autor) {
        System.out.println("Removendo autor " + autor.getNome());
        this.autorDao.remove(autor);
    }

    public List<Autor> getAutores() {
        return this.autorDao.listaTodos();
    }

    public Autor getAutor() {
        return autor;
    }

    public void setAutor(Autor autor) {
        this.autor = autor;
    }
}