Question

我无法将我的接收器注销到另一个活动中。这是：

在我的启动活动A中启动/注册BroadcastReceiver。

活动A：

public class ActivityA extends Activity {
   private PowerButtonReceiver mPowerButtonReceiver = null;

   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);

      setContentView(R.layout.activity_main);

      if (getPowerButtonReceiver() == null)
      {
            mPowerButtonReceiver(new PowerButtonReceiver());                                            
            registerReceiver(mPowerButtonReceiver, new IntentFilter("android.intent.action.SCREEN_ON"));
      }         
   }

public void unregister() {
    try {
        unregisterReceiver(mPowerButtonReceiver);
    } catch (NullPointerException e) {
        e.printStackTrace();
    }       
    if (mPowerButtonReceiver == null) {
        Log.i(TAG,"unregistered PowerButtonReceiver!");
    }       
}

然后我在我的接收器的onReceive（）方法中启动Activity B. 在此之后我进入onCreate（） - Activity B的方法，做我的东西，在onCreate（）结束时，我想取消注册BroadcastReceiver：

活动B：（ - ＆gt; android：launchMode =“singleTop”）

public class ActivityB extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);                 

    setContentView(R.layout.activity_camera);       

    [...do my stuff...]

//un-register PowerButtonReceiver --> call in Activity A

    MainActivity m = new MainActivity();
    m.getParent();
    m.unregister();         
}

我的最后一行开始调用unregister（），但是Receiver为null，看起来它没有得到它的引用。接收方也没有注册，仍然在听。我很确定我的错误是在参考/调用中;但我不明白该怎么做：/

我在这里缺少什么？有人能帮助我吗？

Answer 1

通过intent.putExtra（）方法将您的活动A上下文传递给活动B.然后，而不是MainActivity m = new MainActivity();做MainActivity m = ((MainActivity)(passedContext));。

Answer 2

我已经成功尝试了这样的事情，看看这是否有帮助：我有一个HeadSetTesTActivity，一个Headsetconnectorreciever，ActivityB。
的 HEADSETTESTACTIVITY.JAVA
`public class HeadsettestActivity extends Activity { /** 在第一次创建活动时调用。 * / Headsetconnectorreciever r;

static HeadsettestActivity activity; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); activity=this; Log.d("Inside activity ", "before broadcast reciever registered"); r = new Headsetconnectorreciever(); registerReceiver(r, new IntentFilter(Intent.ACTION_HEADSET_PLUG)); Log.d("Inside activity ", "after broadcast reciever registered"); } public void unregister() { try { if(r!=null){ unregisterReceiver(r); Log.i("HeadsettestActivity","Inside unregister "); } } catch (NullPointerException e) { e.printStackTrace(); } if (r == null) { Log.i("HeadsettestActivity","unregistered PowerButtonReceiver!"); } }

}`

<强> Headsetconnectorreciever
`public class Headsetconnectorreciever扩展BroadcastReceiver { private boolean headsetConnected = false;

@Override public void onReceive(Context context, Intent intent) { Log.d("Inside broadcast reciever ", "Inside onrecieve"); // TODO Auto-generated method stub if (intent.hasExtra("state")){ Log.d("Inside broadcast reciever ", "hasstate"); if (headsetConnected && intent.getIntExtra("state", 0) == 0){ headsetConnected = false; Log.d("Inside broadcast reciever ", "disconnected"); Toast.makeText(context, "Headset is disconnected", Toast.LENGTH_SHORT).show(); } else if (!headsetConnected && intent.getIntExtra("state", 0) == 1){ Log.d("Inside broadcast reciever ", "disconnected"); headsetConnected = true; Intent intent2=new Intent(context, ActivityB.class); context.startActivity(intent2); } } }

}`

最后我的 ACTIVITY B

public class ActivityB extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); Toast.makeText(getApplicationContext(), "Headset is connected", Toast.LENGTH_SHORT).show(); HeadsettestActivity a = HeadsettestActivity.activity ; a.unregister(); }

}

代码实际上有效。

Answer 3

由于您没有关闭我将意图发送到活动A的其他活动，

活动B

boolean unregister = true;
Intent intent = new Intent(this, Activity_A.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP| Intent.FLAG_ACTIVITY_SINGLE_TOP);
intent.putExtra("unregister",unregister);
startActivity(intent);

在活动A上覆盖onNewIntent

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

    if (intent != null) {
        if (intent.getBooleanExtra("unregister", false)) {
            unregister();

        }

    }

}

如何才能正确地从其他活动中取消注册接收器？

3 个答案: