GetFlights.java

// Copyright 2008 Google Inc. All Rights Reserved.
package com.google.appengine.demos.helloorm;

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

import javax.jdo.PersistenceManager;
import javax.persistence.EntityManager;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class GetFlights extends HttpServlet {

  private static final String DEFAULT_QUERY = "select from " + Flight.class.getName();

  @Override
  protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    doGet(req, resp);
  }

  @Override
  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
    resp.setContentType("text/html");
    long start = System.currentTimeMillis();
    Collection<Flight> flights;
    String query = DEFAULT_QUERY;
    String customQuery = req.getParameter("q");
    if (customQuery != null) {
      query = customQuery;
    }
    if (PersistenceStandard.get() == PersistenceStandard.JPA) {
      flights = queryJPA(query);
    } else {
      flights = queryJDO(query);
    }
    printQueryFlightForm(query, resp);

    resp.getWriter().println("<table>");
    printTableHeader(resp);

    printFlights(resp, flights);
    resp.getWriter().println("</table>");
    printAddFlightForm(query, resp);
    resp.getWriter().println("Request time in millis: " + (System.currentTimeMillis() - start));
    resp.getWriter().println("<br>");
    printPersistenceStandardForm(query, resp);
  }

  private Collection<Flight> queryJDO(String query) {
    PersistenceManager pm = PMF.get().getPersistenceManager();
    try {
      List<Flight> flights = (List<Flight>) pm.newQuery(query).execute();
      // Force all results to be pulled back before we close the entity manager.
      // We could have also called pm.detachCopyAll() 
      flights.size();
      return flights;
    } finally {
      pm.close();
    }
  }

  private List<Flight> queryJPA(String query) {
    EntityManager em = EMF.get().createEntityManager();
    try {
      List<Flight> flights = em.createQuery(query).getResultList();
      // force all results to be pulled back before we close the entity manager
      flights.size();
      return flights;
    } finally {
      em.close();
    }
  }

  private void printQueryFlightForm(String query, HttpServletResponse resp) throws IOException {
    PersistenceStandard ps = PersistenceStandard.get();
    resp.getWriter().println("<form action=\"/\" method=\"post\">");
    resp.getWriter().println(ps.name() + " Query for flights: "
        + "<input name=\"q\" type=\"text\" size=\"100\" "
        + "value=\"" + (query == null ? "" : query) + "\"/>");
    resp.getWriter().println("<input type=\"submit\" value=\"Run Query\">");
    resp.getWriter().println("</form>");
  }

  private void printPersistenceStandardForm(String query, HttpServletResponse resp) throws IOException {
    PersistenceStandard ps = PersistenceStandard.get();
    resp.getWriter().println("Persistence standard is " + ps.name());

    resp.getWriter().println("<form action=\"updatePersistenceStandard\" method=\"post\">");
    resp.getWriter().println("<input type=\"submit\" value=\"Switch to " + ps.getAlternate() + "\">");
    resp.getWriter().println(
        "<input name=\"persistenceStandard\" type=\"hidden\" value=\"" + ps.getAlternate() + "\"/>");
    resp.getWriter().println("<input name=\"q\" type=\"hidden\" value=\"" + query + "\"/>");
    resp.getWriter().println("</form>");
  }

  private void printAddFlightForm(String query, HttpServletResponse resp) throws IOException {
    resp.getWriter().println("<form action=\"addFlight\" method=\"post\">");
    resp.getWriter().println("<table>");
    resp.getWriter().println("<tr>");
    resp.getWriter().println("<th>Origin</th><td><input name=\"orig\" type=\"text\"/></td>");
    resp.getWriter().println("<th>Destination</th><td><input name=\"dest\" type=\"text\"/></td>");
    resp.getWriter().println("</tr>");
    resp.getWriter().println("<tr><td><input type=\"submit\" value=\"Add Flight\"></td></tr>");
    resp.getWriter().println("<input name=\"q\" type=\"hidden\" value=\"" + query + "\"/>");
    resp.getWriter().println("</table>");
    resp.getWriter().println("</form>");
  }

  private void printFlights(HttpServletResponse resp, Collection<Flight> flights) throws IOException {
    if (flights.isEmpty()) {
      resp.getWriter().println("<br>No Flights!");
    }
    int index = 1;
    for (Flight f : flights) {
      resp.getWriter().println("<tr>");
      resp.getWriter().println("<td>");
      resp.getWriter().println("<a href=\"getFlight?key=" + f.getId() + "\"> " + index++ + "</a>");
      resp.getWriter().println("</td>");
      resp.getWriter().println("<td>");
      resp.getWriter().println(f.getOrig());
      resp.getWriter().println("</td>");
      resp.getWriter().println("<td>");
      resp.getWriter().println(f.getDest());
      resp.getWriter().println("</td>");
      resp.getWriter().println("</tr>");
    }
  }

  private void printTableHeader(HttpServletResponse resp) throws IOException {
    resp.getWriter().println("<tr>");
    resp.getWriter().println("<td>");
    resp.getWriter().println("</td>");
    resp.getWriter().println("<td>");
    resp.getWriter().println("Origin");
    resp.getWriter().println("</td>");
    resp.getWriter().println("<td>");
    resp.getWriter().println("Dest");
    resp.getWriter().println("</td>");
    resp.getWriter().println("</tr>");
  }

}