Android 開發 (十七) Hello GCM

甚麼是GCM

server端可以藉由此通知client端一些消息，例如: line的訊息通知，軟體更新通知，或者某些商品的特賣通知。

如何實現GCM

首先必須先寫出client端程式，client端必須註冊GCM，並且設定一個receiver去接收GCM

以下是範例

  GCMRegistrar.checkDevice(this); 
  GCMRegistrar.checkManifest(this); 
  final String regId = GCMRegistrar.getRegistrationId(this); 
  Log.d("Ted", "regId = " + regId); 
  if (regId.equals("")) { 
     GCMRegistrar.register(this, Project_ID); 
  } else { 
     Log.d("Ted", "Already registered"); 
  }              

上面幾行會註冊GCM，接著在manifest裡面加入以下的程式

   <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.GET_ACCOUNTS" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.VIBRATE" />

    <permission
        android:name="com.example.momoandroid.permission.C2D_MESSAGE"
        android:protectionLevel="signature" />

    <uses-permission android:name="com.example.momoandroid.permission.C2D_MESSAGE" />
    <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.gcmsample.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <receiver
            android:name="com.google.android.gcm.GCMBroadcastReceiver"
            android:permission="com.google.android.c2dm.permission.SEND" >
            <intent-filter>
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
                <action android:name="com.google.android.c2dm.intent.REGISTRATION" />

                <category android:name="com.example.gcmsample" />
            </intent-filter>
        </receiver>

        <service android:name=".GCMIntentService" />
    </application>

使用receiver接收gcm，並且設定service為 GCMIntentService
然後GCMIntentService繼承 GCMBaseIntentService
接著在onMessage也就是收到訊息時做相關的動作

  NotificationManager notificationManager = (NotificationManager) context
    .getSystemService(NOTIFICATION_SERVICE);

  /*
   * Intent notifyIntent = new Intent(context ,MainActivity.class);
   * notifyIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); PendingIntent
   * appIntent = PendingIntent.getActivity(context,0, notifyIntent, 0);
   */

  Notification notification = new Notification();
  notification.icon = R.drawable.ic_launcher;
  notification.tickerText = "notification on status bar.";
  notification.defaults = Notification.DEFAULT_ALL;
  notification.setLatestEventInfo(context, "Title", message, null);
  notificationManager.notify(0, notification);

如上面的程式碼，這樣就可以在收到訊息時產生推撥
然後在 OnRegiter時將 Register_Id記起來之後在server端會使用到

上面的程式碼有個Project_ID必須去google developer console申請
首先去 google console 開啟一個project  https://cloud.google.com/console/project
接著就可以在overview欄位找到Project Number ，也就是我們需要的Project_ID

接著開啟 google cloud messaging for android

接著create key create browser key

接著將API key 記起來  之後在server端需要使用

目前我們已經取得了 server 端需要的API_Key 以及 Register_Id

接著我們只需要開創一個java project

然後key入以下程式碼

 Sender sender = new Sender(API_Key );

            ArrayList<String> devicesList = new ArrayList<String>();
            
            String device =Register_Id;
           devicesList.add(device);

            Message message = new Message.Builder()
                    //.collapseKey("message")
                    //.timeToLive(241000)
                    .delayWhileIdle(true)
                    .addData("message", "Your message send")
                    .build();



          
            MulticastResult result = sender.send(message, devicesList, 1);
      

            System.out.println(result.toString());
            if (result.getResults() != null) {
                int canonicalRegId = result.getCanonicalIds();
                if (canonicalRegId != 0) {
                }
            } else {
                int error = result.getFailure();
                System.out.println(error);
            }

當執行完java project 訊息就會被送出，然後client端就會出現如下圖的推撥

在這邊附上 sample code

附註   java project 必須 import一些jar檔  檔案也會附在sample code裡

GCMSample為 client端
sendMessage為 server端