JavascriptConfigServlet.java

package net.socialgamer.cah.servlets;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletConfig;
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 net.socialgamer.cah.CahModule.CookieDomain;
import net.socialgamer.cah.StartupUtils;

import com.google.inject.Injector;
import com.google.inject.Key;


@WebServlet("/js/cah.config.js")
public class JavascriptConfigServlet extends HttpServlet {

  private static final long serialVersionUID = 4287566906479434127L;

  private String configString;

  @Override
  public void init(final ServletConfig config) throws ServletException {
    final StringBuilder builder = new StringBuilder(256);
    //TODO: these should be loadable from the web.xml
    builder.append("cah.DEBUG = false;\n");
    builder.append("cah.SILENT_DEBUG = false;\n");

    String contextPath = config.getServletContext().getContextPath();
    if (!contextPath.endsWith("/")) {
      contextPath += "/";
    }
    builder.append(String.format("cah.AJAX_URI = '%sAjaxServlet';\n", contextPath));
    builder.append(String.format("cah.LONGPOLL_URI = '%sLongPollServlet';\n", contextPath));

    configString = builder.toString();

    super.init(config);
  }

  @Override
  protected void doGet(final HttpServletRequest req, final HttpServletResponse resp)
      throws ServletException, IOException {

    // We have to do this every time since it comes from the properties file and that can change...
    final StringBuilder builder = new StringBuilder(256);
    // Ideally we'd figure out how to make this Servlet itself injectable but I don't have time.
    final Injector injector = (Injector) getServletContext().getAttribute(StartupUtils.INJECTOR);
    final String cookieDomain = injector.getInstance(Key.get(String.class, CookieDomain.class));
    builder.append(String.format("cah.COOKIE_DOMAIN = '%s';\n", cookieDomain));

    resp.setContentType("text/javascript");
    final PrintWriter out = resp.getWriter();
    out.println(configString + builder.toString());
    out.flush();
    out.close();
  }
}