任何应用程序都可以广播具有动作名称“ android.intent.action.MEDIA_BUTTON”的Intent

Question

My application is registered for intent ( "android.intent.action.MEDIA_BUTTON" ) to handle wired headset key pressed using below code

<receiver
    android:name=".HeadsetEventReceiver"
    android:enabled="true" >
    <intent-filter android:priority="2147483647" >
        <action android:name="android.intent.action.MEDIA_BUTTON" />
    </intent-filter>
</receiver>

Receiver HeadsetEventReceiver does some operation on receiving this Intent.

Now I have a sample application which broadcast an Intent with action as "android.intent.action.MEDIA_BUTTON" with valid KeyEvent object using below code.

Intent newIntent = new Intent("android.intent.action.MEDIA_BUTTON")  ;
KeyEvent event = new KeyEvent(System.currentTimeMillis(), System.currentTimeMillis(), KeyEvent.ACTION_DOWN, 79, 1, 1, 1, 1, 1, InputDevice.SOURCE_TOUCHPAD);
newIntent.putExtra(Intent.EXTRA_KEY_EVENT, event);
getApplicationContext().sendBroadcast(newIntent);

My application is receiving this Intent and processing this data as if it is actually broadcast due to headset key press.

My query is when any application try to send broadcast with native Intents(eg: "android.intent.action.BOOT_COMPLETED" ) securityException is thrown. Why does it not apply for the above Intent( "android.intent.action.MEDIA_BUTTON" ).

Answer 1

Since 4.0 or greater the Android document says that you have to use registerMediaButtonEventReceiver for registering the intent action. Without registering to registerMediaButtonEventReceiver you won't get broadcast message.

Below is the code which is documented here

AudioManager am = mContext.getSystemService(Context.AUDIO_SERVICE);
...

// Start listening for button presses
am.registerMediaButtonEventReceiver(RemoteControlReceiver);
...

// Stop listening for button presses
am.unregisterMediaButtonEventReceiver(RemoteControlReceiver);

So if you are using registerMediaButtonEventReceiver then you would get the broadcast else you won't.