android - 在android中动态注册/注销广播接收器

Question

我想通过广播动态注册和注销我的接收器类:“android.net.wifi.STATE_CHANGE”如果我在 list 中这样做，效果会很好。但这使它成为静态的。我想在 Activity 类中动态地进行。它在 Activity 类中对应的命令是什么？

这就是我的代码...由于注册和取消注册(多次)我的接收器(正在启动服务)，我遇到了问题。

public class startScreen extends Activity {
    /** Called when the activity is first created. */

    private BroadcastReceiver receiver = new BroadcastReceiver() {    

        @Override
        public void onReceive(Context context, Intent intent) {
            Intent serviceIntent = new Intent();
            serviceIntent.setAction("com.example.MyService");
            context.startService(serviceIntent);    
        }    
    };

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

        final IntentFilter filter = new IntentFilter();
        filter.addAction("android.net.wifi.STATE_CHANGE");   

        Button button = (Button) findViewById(R.id.button1);
        final ToggleButton toggleButton = (ToggleButton) findViewById(R.id.toggleButton1);

        try {
                ...some code...
            if (bool == true) {
                toggleButton.setChecked(true);
                this.registerReceiver(receiver, filter);
            } else
                toggleButton.setChecked(false);
        } catch (Exception e) {
            Log.e("Error", "Database", e);
        } finally {
                ...
        }

        toggleButton.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {
                if ((toggleButton.isChecked())) {
                    getBaseContext().registerReceiver(receiver, filter);

                } else {
                    if (receiver != null) {
                        getBaseContext().unregisterReceiver(receiver);
                        receiver = null;
                    }

                }
            }
        });
    }    

    @Override
    protected void onResume() {
        super.onResume();
        if (bool == true) {
            if (receiver == null)
                this.registerReceiver(receiver, filter);
        }
    }

    @Override
    protected void onPause() {
        super.onPause();
        if (receiver != null) {
            this.unregisterReceiver(receiver);
            receiver = null;
        }
    }
}

Answer 1

LocalBroadcastManager 类用于注册 Intent 广播并将其发送到进程中的本地对象。由于您的 Activity 不会离开您的应用程序，因此速度更快、更安全。

以下示例显示了一个注册名为 my-event 的客户事件的 Activity 。

@Override
public void onResume() {
super.onResume();

   // Register mMessageReceiver to receive messages.
   LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
     new IntentFilter("my-event"));
}

// handler for received Intents for the "my-event" event 
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
   // Extract data included in the Intent
   String message = intent.getStringExtra("message");
   Log.d("receiver", "Got message: " + message);
 }
};

@Override
protected void onPause() {
   // Unregister since the activity is not visible
   LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
   super.onPause();
} 
// This method is assigned to button in the layout
// via the onClick property
public void onClick(View view) {
   sendMessage();
}

// Send an Intent with an action named "my-event". 
private void sendMessage() {
  Intent intent = new Intent("my-event");
  // add data
  intent.putExtra("message", "data");
  LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}