Google Cloud Messaging(GCM)-Android推播通知訊息註冊

註冊API Key：
如果要使用Google API，一定要先到Google Developers Console中拿到API Key。

圖1.建立專案

圖2.啟用GCM API

圖3.建立金鑰

圖4.取得API Key

圖5.取得專案ID

Gradle：

compile "com.google.android.gms:play-services:8.3.0"

AndroidManifest.xml：

<uses-sdk android:minSdkVersion="8" android:targetSdkVersion="17"/>
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
<permission android:name="YOUR_PACKAGE_NAME.permission.C2D_MESSAGE"
            android:protectionLevel="signature" />
<uses-permission android:name="YOUR_PACKAGE_NAME.permission.C2D_MESSAGE" />
<uses-permission android:name="android.permission.VIBRATE"/>

YOUR_PACKAGE_NAME：更改為您的專案名稱
android.permission.VIBRATE：開起震動

<receiver
   android:name="YOUR_PACKAGE_NAME.GcmBroadcastReceiver"
   android:exported="true"
   android:permission="com.google.android.c2dm.permission.SEND" >
   <intent-filter>
       <action android:name="com.google.android.c2dm.intent.RECEIVE" />
       <category android:name="YOUR_PACKAGE_NAME" />
   </intent-filter>
</receiver>
<service android:name=".GcmIntentService" />

YOUR_PACKAGE_NAME：更改為您的專案名稱

GcmIntentService：

public class GcmIntentService extends IntentService {
    public static final int NOTIFICATION_ID = 1;
    public GcmIntentService() {
        super("GcmIntentService");
    }

    @Override
    protected void onHandleIntent(Intent intent) {
        Bundle extras = intent.getExtras();
        if (!extras.isEmpty()) {
            try {
                //分析GCM推送的JSON資料
                JSONTokener jsonTokener = new JSONTokener(extras.toString().replaceAll("Bundle", ""));
                JSONArray jsons = (JSONArray) jsonTokener.nextValue();
                JSONObject jsonObject = (JSONObject)jsons.get(0);
                //取得message屬性的內容
                sendNotification(jsonObject.getString("message"));

            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        GcmBroadcastReceiver.completeWakefulIntent(intent);
    }

    private void sendNotification(String msg) {
        //設定點選推播要啟動的Activity
        PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
                new Intent(this, MainActivity.class), 0);
        //設定新通知
        NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(this);
        mBuilder.setSmallIcon(R.drawable.ic_launcher);
        mBuilder.setTicker("new message");
        mBuilder.setContentText(msg);
        mBuilder.setContentTitle("Ocean's 通知");
        mBuilder.setAutoCancel(true);
        mBuilder.setContentIntent(contentIntent);
        //顯示通知
        NotificationManager mNotificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        mNotificationManager.notify(NOTIFICATION_ID, mBuilder.build());
    }

}

GcmBroadcastReceiver：

public class GcmBroadcastReceiver extends WakefulBroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        ComponentName comp = new ComponentName(context.getPackageName(), GcmIntentService.class.getName());
        startWakefulService(context, (intent.setComponent(comp)));
        setResultCode(Activity.RESULT_OK);
    }

}

MainActivity：

public class MainActivity extends AppCompatActivity {
    private final static int PLAY_SERVICES_RESOLUTION_REQUEST = 9000;
    public static final String PROPERTY_REG_ID = "gcmtest-1152";
    public static final String SENDER_ID = "219666876033";
    private GoogleCloudMessaging gcm;
    private String regid;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        if (checkPlayServices()) {
            gcm = GoogleCloudMessaging.getInstance(this);
            regid = getRegistrationId();
            if (regid.length() == 0) {
                registerInBackground();
            } else {
                Toast.makeText(MainActivity.this, "Already registered", Toast.LENGTH_SHORT).show();
                Log.i("regid", regid);
            }
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }


    //檢查是否支援GooglePlayServices
    private boolean checkPlayServices() {
        int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
        if (resultCode != ConnectionResult.SUCCESS) {
            if (GooglePlayServicesUtil.isUserRecoverableError(resultCode)) {
                GooglePlayServicesUtil.getErrorDialog(resultCode, this,
                        PLAY_SERVICES_RESOLUTION_REQUEST).show();
            } else {
                finish();
            }
            return false;
        }
        return true;
    }

    //取得推播的ID
    private String getRegistrationId() {
        final SharedPreferences prefs = getSharedPreferences(MainActivity.class.getSimpleName(), Context.MODE_PRIVATE);
        String registrationId = prefs.getString(PROPERTY_REG_ID, "");
        if (registrationId.isEmpty()) {
            return "";
        }
        return registrationId;
    }

    //註冊推播
    private void registerInBackground() {
        new AsyncTask() {
            @Override
            protected Void doInBackground(Void... params) {
                try {
                    if (gcm == null) {
                        gcm = GoogleCloudMessaging.getInstance(MainActivity.this);
                    }
                    regid = gcm.register(SENDER_ID);
                    storeRegistrationId(regid);
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
                return null;
            }
            @Override
            protected void onPostExecute(Void result) {
                super.onPostExecute(result);
                Toast.makeText(MainActivity.this, "Successful registration", Toast.LENGTH_SHORT).show();
                Log.i("regid", regid);
            }
        }.execute(null, null, null);
    }
    //通知GCM推播ID使用
    private void storeRegistrationId(String regId)
    {
        SharedPreferences prefs = getSharedPreferences(MainActivity.class.getSimpleName(), Context.MODE_PRIVATE);
        SharedPreferences.Editor editor = prefs.edit();
        editor.putString(PROPERTY_REG_ID, regId);
        editor.commit();
    }
}

PROPERTY_REG_ID：儲存GCM註冊ID之Key。
SENDER_ID：圖5所得到的專案ID。
※regid：接受訊息裝置的辨識Key。

測試推播server：
(來自知道原因問題就解決一半)：http://emlscer.no-ip.info:8080/sample/Send.php
GOOGLE_API_KEY：你所註冊的金鑰(圖4)。
APP_REG_ID：你取得的regid。
Message：你欲傳送之訊息。
※中文無法推，PHP沒有對中文做編碼。
資料來源：
http://gnehcic.azurewebsites.net/android%E4%BD%BF%E7%94%A8google%E6%8E%A8%E6%92%AD%E6%9C%8D%E5%8B%99/ (知道原因問題就解決一半)