Android Open Source - libgdx-chat-example Http Dispatch Servlet

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License

The source code is released under:

Apache License

Java Source Code

package org.stofkat.chat.server.http.dispatch;
/* w w  w  .ja v a  2s . c om*/
import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

import org.stofkat.chat.common.actions.Action;
import org.stofkat.chat.common.exceptions.DispatchException;
import org.stofkat.chat.common.exceptions.ServiceException;
import org.stofkat.chat.common.results.Result;
import org.stofkat.chat.server.DefaultActionHandlerRegistry;
import org.stofkat.chat.server.Dispatch;
import org.stofkat.chat.server.InstanceActionHandlerRegistry;
import org.stofkat.chat.server.SimpleDispatch;
import org.stofkat.chat.server.actionhandlers.ChatActionHandler;
import org.stofkat.chat.server.actionhandlers.UpdateActionHandler;

/**
 * Most code here is ripped from the AbstractStandardDispatchServlet class in
 * the http-dispatch project.
 * 
 * @author Leejjon
 */
public class HttpDispatchServlet extends HttpServlet {
  private static final long serialVersionUID = 1L;

  private Dispatch dispatch;

  public HttpDispatchServlet() {
    InstanceActionHandlerRegistry registry = new DefaultActionHandlerRegistry();
    registry.addHandler(new ChatActionHandler());
    registry.addHandler(new UpdateActionHandler());
    dispatch = new SimpleDispatch(registry);
  }

  @Override
  protected void doPost(HttpServletRequest request, HttpServletResponse res) throws ServletException, IOException {
    Throwable t = null;
    byte[] output = null;
    try {
      Object result = null;
      try {
        System.out.println("trying to extract action from request");

        BufferedInputStream bis = new BufferedInputStream(request.getInputStream());
        ObjectInputStream ois = new ObjectInputStream(bis);
        result = getResult(ois, request);
        ois.close();
        System.out.println("created response result, sending it back");

      } catch (DispatchException e) {
        System.out.println("generated dispatch exception, sending it back");
        result = e;
      }
      ByteArrayOutputStream baos = new ByteArrayOutputStream();
      ObjectOutputStream oos = new ObjectOutputStream(baos);
      {
        oos.writeObject(result);
      }
      output = baos.toByteArray();

      System.out.println("sent response back...");
    } catch (Throwable e) {
      System.out.println("Unable to process request" /* , e */);
      t = e;
    }
    processOutput(res, t, output);

  }

  @SuppressWarnings("unchecked")
  protected Object getResult(ObjectInputStream ois, HttpServletRequest request) throws IOException, ClassNotFoundException, DispatchException {
    Object result;
    Action<? extends Result> input = (Action<? extends Result>) ois.readObject();
    System.out.println("got the action from the client:" + input);

    result = execute(input, request.getSession());
    return result;
  }

  protected void processOutput(HttpServletResponse res, Throwable t, byte[] output) throws IOException {
    ServletOutputStream sos = res.getOutputStream();

    if (output != null) {
      res.setContentType("application/octet-stream");
      res.setContentLength(output.length);
      sos.write(output);
    } else {
      res.setContentType("text/plain");
      byte[] message = t.getMessage().getBytes();
      res.setContentLength(message.length);
      sos.write(message);
    }

    sos.flush();
    sos.close();
  }
  
  private <R extends Result> R execute(Action<R> action, HttpSession session) throws DispatchException {
    try {
      if (dispatch == null)
        throw new ServiceException("No dispatch found for servlet '" + getServletName() + "' . Please verify your server-side configuration.");

      return dispatch.execute(action, session);
    } catch (RuntimeException e) {
      log("Exception while executing " + action.getClass().getName() + ": " + e.getMessage(), e);
      throw new ServiceException(e);
    }
  }
}

Java Source Code List

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