android - 粘性广播接收器 - 它们如何工作？

Question

广播接收器是粘性的还是 Intent 粘性的？ 据我所知，“粘性 Intent 是那些在广播后仍然存在的 Intent 。不存在粘性广播接收器之类的东西；只有可以监听粘性 Intent 的接收器。”

但是我们如何让 Intent 具有粘性呢？ sendStickyBroadcast(intentA) 是使 IntentA 粘性的唯一方法吗？如果是，如果我同时调用 sendStickyBroadcast(intentA) 和 sendBroadcast(intentA) 会发生什么？ IntentA 是否可供 future 的接收者使用？

我想用 Logcat 测试这个场景，但我收到了意外的日志:

public class MainActivity extends Activity {

    private static final String CUSTOM_INTENT = "com.ashok.abacussb.my_intent";
    Button button;
    Receiver1 receiver1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        sendBroadcast(new Intent(CUSTOM_INTENT));
        Log.d("abd", "after sendBroadcast() "+ Thread.currentThread().getName());

        receiver1 = new Receiver1();

        button = (Button) findViewById(R.id.button);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Log.d("abd", "inside onClick()");
                Intent intent = registerReceiver(receiver1, new IntentFilter(CUSTOM_INTENT));
                Log.d("abd", (intent == null ? "null": ""+intent));
            }
        });
    }
}

public class Receiver1 extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.d("abd", "inside Receiver1 onReceive() "+ Thread.currentThread().getName());
    }
}

和日志:

09-21 16:26:43.845: D/abd(26620): after sendBroadcast() main
09-21 16:26:49.665: D/abd(26620): inside onClick()
09-21 16:26:49.685: D/abd(26620): Intent { act=com.ashok.abacussb.my_intent flg=0x10 }
09-21 16:26:49.770: D/abd(26620): inside Receiver1 onReceive() main

Receiver1 在按钮单击时注册，这显然是在执行 sendBroadcast() 之后。为什么执行 onReceive() 方法并且 registerReceiver() 返回的 Intent 不为 NULL，因为它不是 sendStickyBroadcast() ？

Answer 1

Are Broadcast Receivers sticky or Intents sticky?

如果您拥有发送此类广播的适当权限，则通过 sendStickyBroadcast() 发送的广播 Intent 是粘性的。

Is sendStickyBroadcast(intentA) is the only way to make intentA sticky?

是的。

If yes, what would happen if I call both sendStickyBroadcast(intentA) and sendBroadcast(intentA) ? Will the intentA be available for future receivers?

据我所知，该行为没有记录。我不建议使用该模式。

Why is the onReceive() method executed & the intent returned by registerReceiver() not NULL, since it was not a sendStickyBroadcast() ?

也许您之前曾针对同一操作字符串发送过粘性广播。重新启动您的设备或模拟器并再次尝试测试。