/** Displays the existing messages and offer the option to send a new one. */
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
resp.setContentType("text/html");
PrintWriter out = resp.getWriter();
out.print("<html><body>");
out.print("<head>");
out.print(" <title>GCM Demo</title>");
out.print(" <link rel='icon' href='favicon.png'/>");
out.print("</head>");
String status = (String) req.getAttribute(ATTRIBUTE_STATUS);
if (status != null) {
out.print(status);
}
List<String> devices = Datastore.getDevices();
if (devices.isEmpty()) {
out.print("<h2>No devices registered!</h2>");
} else {
out.print("<h2>" + devices.size() + " device(s) registered!</h2>");
out.print("<form name='form' method='POST' action='sendAll'>");
out.print("<input type='submit' value='Send Message' />");
out.print("</form>");
}
out.print("</body></html>");
resp.setStatus(HttpServletResponse.SC_OK);
}
/** Processes the request to add a new message. */
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp)
throws IOException, ServletException {
List<String> devices = Datastore.getDevices();
String status;
if (devices.isEmpty()) {
status = "Message ignored as there is no device registered!";
} else {
// NOTE: check below is for demonstration purposes; a real application
// could always send a multicast, even for just one recipient
if (devices.size() == 1) {
// send a single message using plain post
String registrationId = devices.get(0);
Message message = new Message.Builder().build();
Result result = sender.send(message, registrationId, 5);
status = "Sent message to one device: " + result;
} else {
// send a multicast message using JSON
// must split in chunks of 1000 devices (GCM limit)
int total = devices.size();
List<String> partialDevices = new ArrayList<String>(total);
int counter = 0;
int tasks = 0;
for (String device : devices) {
counter++;
partialDevices.add(device);
int partialSize = partialDevices.size();
if (partialSize == MULTICAST_SIZE || counter == total) {
asyncSend(partialDevices);
partialDevices.clear();
tasks++;
}
}
status = "Asynchronously sending " + tasks + " multicast messages to " + total + " devices";
}
}
req.setAttribute(HomeServlet.ATTRIBUTE_STATUS, status.toString());
getServletContext().getRequestDispatcher("/home").forward(req, resp);
}