在GCM onMessage事件期间检查应用是否已打开？

Question

我想知道如何检查我的应用程序是否已打开,并且当onMessage()从GCM 接收时,用户当前可以看到该应用程序.起初,我只是使用自己的boolean isVisible,但后来我意识到这不可靠,因为如果应用程序没有打开,我用来访问该标志的对象是null.虽然这本身可以用来看看应用程序是否开放,但似乎有点混乱.Android中是否有一种方法可以从系统级别以某种方式检查应用程序当前是否已打开,以及用户是否正在查看应用程序？请记住,应用程序可以在技术上运行,但不可见,因为用户最近按下"主页"按钮将其发送到后台.

@Override
protected void onMessage(Context arg0, Intent arg1) {
    String turn = intent.getExtras().getString("turn");
    if (turn.equals("yours"){
         if (/*app is open*/){ <------------------ what can go here?
             // dont generate a notification
             // display something in the game instead
         }
         else{
             // generate notification telling player its their turn
         }
    }
}

Answer 1

我会使用订单广播来做到这一点.

在你的onMessage方法中:

Intent responseIntent = new Intent("com.yourpackage.GOT_PUSH");
sendOrderedBroadcast(responseIntent, null);

在您的活动中:

public class YourActivity extends Activity {

    final BroadcastReceiver mBroadcastReceiver = new BroadcastReceiver() {

        @Override
        public void onReceive(Context context, Intent intent) {
            //Right here do what you want in your activity
            abortBroadcast();
        }
    };

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

        //.....
    }

    @Override
    protected void onPause() {
        unregisterReceiver(mBroadcastReceiver);
        super.onPause();
    }

    @Override
    protected void onResume() {
        IntentFilter filter = new IntentFilter("com.yourpackage.GOT_PUSH");
        filter.setPriority(2);
        registerReceiver(mBroadcastReceiver, filter);
        super.onResume();
    }
}

另一个BroadcastReceiver

public class SecondReceiver extends BroadcastReceiver {

    @Override
    public void onReceive(Context context, Intent intent) {
        //In this receiver just send your notification
    }

}

表现:

<activity
    android:name=".YourActivity"
    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=".SecondReceiver">
    <intent-filter
        android:priority="1">
        <action
            android:name="com.yourpackage.GOT_PUSH" />
    </intent-filter>
</receiver>

基本上在onMessage你发送一个Intent 的方法中,YourActivity如果它正在运行并且在前台,则由内部注册的BroadcastReceiver首先接收,否则它被接收SecondReceiver.

Answer 2

使用 SharedPreferences 保存布尔值 isVisible，当您从首选项中获取值时，您可以添加默认值。

SharedPreferences settings = context.getSharedPreferences("NAME_XXX", Activity.MODE_PRIVATE);
settings.getBoolean("visible", false);