CarrosServlet.java

package br.com.livro.servlets;

import java.io.IOException;
import java.util.List;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import br.com.livro.domain.Carro;
import br.com.livro.domain.CarroService;
import br.com.livro.domain.Response;
import br.com.livro.util.RegexUtil;
import br.com.livro.util.ServletUtil;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

@WebServlet("/carros/*")
public class CarrosServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
	private CarroService carroService = new CarroService();

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String requestUri = req.getRequestURI();
		Long id = RegexUtil.matchId(requestUri);
		if (id != null) {
			// Informou o id
			Carro carro = carroService.getCarro(id);
			if (carro != null) {
				Gson gson = new GsonBuilder().setPrettyPrinting().create();
				String json = gson.toJson(carro);
				ServletUtil.writeJSON(resp, json);
			} else {
				resp.sendError(404, "Carro não encontrado");
			}
		} else {
			// Lista de carros
			List<Carro> carros = carroService.getCarros();
			Gson gson = new GsonBuilder().setPrettyPrinting().create();
			String json = gson.toJson(carros);
			ServletUtil.writeJSON(resp, json);
		}
	}

	@Override
	public void doPost(HttpServletRequest request, HttpServletResponse resp)
			throws IOException, ServletException {
		// Cria o carro
		Carro carro = getCarroFromRequest(request);
		// Salva o carro
		carroService.save(carro);
		// Escreve o JSON do novo carro salvo.
		Gson gson = new GsonBuilder().setPrettyPrinting().create();
		String json = gson.toJson(carro);
		ServletUtil.writeJSON(resp, json);
	}

	// Lê os parâmetros da request e cria o objeto Carro.
	private Carro getCarroFromRequest(HttpServletRequest request) {
		Carro c = new Carro();
		String id = request.getParameter("id");
		if (id != null) {
			// Se informou o id, busca o objeto do banco de dados.
			c = carroService.getCarro(Long.parseLong(id));
		}
		c.setNome(request.getParameter("nome"));
		c.setDesc(request.getParameter("descricao"));
		c.setUrlFoto(request.getParameter("url_foto"));
		c.setUrlVideo(request.getParameter("url_video"));
		c.setLatitude(request.getParameter("latitude"));
		c.setLongitude(request.getParameter("longitude"));
		c.setTipo(request.getParameter("tipo"));
		return c;
	}

	@Override
	protected void doDelete(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		String requestUri = req.getRequestURI();
		Long id = RegexUtil.matchId(requestUri);
		if (id != null) {
			carroService.delete(id);
			Response r = Response.Ok("Carro excluído com sucesso");
			Gson gson = new GsonBuilder().setPrettyPrinting().create();
			String json = gson.toJson(r);
			ServletUtil.writeJSON(resp, json);
		} else {
			// URL inválida
			resp.sendError(404, "URL inválida");
		}
	}

}