RegisterActivity.java

package com.umich.umd.obdpractice;

import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.Button;

/**
 * An activity that communicates with your App Engine backend via Cloud
 * Endpoints.
 * 
 * When the user hits the "Register" button, a message is sent to the backend
 * (over endpoints) indicating that the device would like to receive broadcast
 * messages from it. Clicking "Register" also has the effect of registering this
 * device for Google Cloud Messaging (GCM). Whenever the backend wants to
 * broadcast a message, it does it via GCM, so that the device does not need to
 * keep polling the backend for messages.
 * 
 * If you've generated an App Engine backend for an existing Android project,
 * this activity will not be hooked in to your main activity as yet. You can
 * easily do so by adding the following lines to your main activity:
 * 
 * Intent intent = new Intent(this, RegisterActivity.class);
 * startActivity(intent);
 * 
 * To make the sample run, you need to set your PROJECT_NUMBER in
 * GCMIntentService.java. If you're going to be running a local version of the
 * App Engine backend (using the DevAppServer), you'll need to toggle the
 * LOCAL_ANDROID_RUN flag in CloudEndpointUtils.java. See the javadoc in these
 * classes for more details.
 * 
 * For a comprehensive walkthrough, check out the documentation at
 * http://developers.google.com/eclipse/docs/cloud_endpoints
 */
public class RegisterActivity extends Activity {

  enum State {
    REGISTERED, REGISTERING, UNREGISTERED, UNREGISTERING
  }

  private State curState = State.UNREGISTERED;
  private OnTouchListener registerListener = null;
  private OnTouchListener unregisterListener = null;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_register);

    Button regButton = (Button) findViewById(R.id.regButton);

    registerListener = new OnTouchListener() {
      @Override
      public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
          if (GCMIntentService.PROJECT_NUMBER == null
              || GCMIntentService.PROJECT_NUMBER.length() == 0) {
            showDialog("Unable to register for Google Cloud Messaging. "
                + "Your application's PROJECT_NUMBER field is unset! You can change "
                + "it in GCMIntentService.java");
          } else {
            updateState(State.REGISTERING);
            try {
              GCMIntentService.register(getApplicationContext());
            } catch (Exception e) {
              Log.e(RegisterActivity.class.getName(),
                  "Exception received when attempting to register for Google Cloud "
                      + "Messaging. Perhaps you need to set your virtual device's "
                      + " target to Google APIs? "
                      + "See https://developers.google.com/eclipse/docs/cloud_endpoints_android"
                      + " for more information.", e);
              showDialog("There was a problem when attempting to register for "
                  + "Google Cloud Messaging. If you're running in the emulator, "
                  + "is the target of your virtual device set to 'Google APIs?' "
                  + "See the Android log for more details.");
              updateState(State.UNREGISTERED);
            }
          }
          return true;
        case MotionEvent.ACTION_UP:
          return true;
        default:
          return false;
        }
      }
    };

    unregisterListener = new OnTouchListener() {
      @Override
      public boolean onTouch(View v, MotionEvent event) {
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
        case MotionEvent.ACTION_DOWN:
          updateState(State.UNREGISTERING);
          GCMIntentService.unregister(getApplicationContext());
          return true;
        case MotionEvent.ACTION_UP:
          return true;
        default:
          return false;
        }
      }
    };

    regButton.setOnTouchListener(registerListener);
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_register, menu);
    return true;
  }

  @Override
  protected void onNewIntent(Intent intent) {
    super.onNewIntent(intent);

    /*
     * If we are dealing with an intent generated by the GCMIntentService
     * class, then display the provided message.
     */
    if (intent.getBooleanExtra("gcmIntentServiceMessage", false)) {

      showDialog(intent.getStringExtra("message"));

      if (intent.getBooleanExtra("registrationMessage", false)) {

        if (intent.getBooleanExtra("error", false)) {
          /*
           * If we get a registration/unregistration-related error,
           * and we're in the process of registering, then we move
           * back to the unregistered state. If we're in the process
           * of unregistering, then we move back to the registered
           * state.
           */
          if (curState == State.REGISTERING) {
            updateState(State.UNREGISTERED);
          } else {
            updateState(State.REGISTERED);
          }
        } else {
          /*
           * If we get a registration/unregistration-related success,
           * and we're in the process of registering, then we move to
           * the registered state. If we're in the process of
           * unregistering, the we move back to the unregistered
           * state.
           */
          if (curState == State.REGISTERING) {
            updateState(State.REGISTERED);
          } else {
            updateState(State.UNREGISTERED);
          }
        }
      }

    }
  }

  private void updateState(State newState) {
    Button registerButton = (Button) findViewById(R.id.regButton);
    switch (newState) {
    case REGISTERED:
      registerButton.setText("Unregister");
      registerButton.setOnTouchListener(unregisterListener);
      registerButton.setEnabled(true);
      break;

    case REGISTERING:
      registerButton.setText("Registering...");
      registerButton.setEnabled(false);
      break;

    case UNREGISTERED:
      registerButton.setText("Register");
      registerButton.setOnTouchListener(registerListener);
      registerButton.setEnabled(true);
      break;

    case UNREGISTERING:
      registerButton.setText("Unregistering...");
      registerButton.setEnabled(false);
      break;
    }
    curState = newState;
  }

  private void showDialog(String message) {
    new AlertDialog.Builder(this)
        .setMessage(message)
        .setPositiveButton(android.R.string.ok,
            new DialogInterface.OnClickListener() {
              public void onClick(DialogInterface dialog, int id) {
                dialog.dismiss();
              }
            }).show();
  }

}