UfoDataServlet.java

package com.google.codeu.servlets;

import com.google.gson.Gson;
import com.google.gson.JsonArray;
import java.io.IOException;
import java.util.Scanner;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/** Returns UFO data as a JSON array, e.g. [{"lat": 38.4404675, "lng": -122.7144313}] */
@WebServlet("/ufo-data")
public class UfoDataServlet extends HttpServlet {

  JsonArray ufoSightingArray;

  @Override
  public void init() {
    ufoSightingArray = new JsonArray();
    Gson gson = new Gson();
    Scanner scanner = new Scanner(getServletContext().getResourceAsStream("/WEB-INF/ufo-data.csv"));
    while (scanner.hasNextLine()) {
      String line = scanner.nextLine();
      String[] cells = line.split(",");

      String state = cells[0];
      double lat = Double.parseDouble(cells[1]);
      double lng = Double.parseDouble(cells[2]);

      ufoSightingArray.add(gson.toJsonTree(new UfoSighting(state, lat, lng)));
    }
    scanner.close();
  }

  @Override
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
    response.setContentType("application/json");
    response.getOutputStream().println(ufoSightingArray.toString());
  }

  private static class UfoSighting {
    String state;
    double lat;
    double lng;

    private UfoSighting(String state, double lat, double lng) {
      this.state = state;
      this.lat = lat;
      this.lng = lng;
    }
  }
}