Question

我想通过广播动态注册和取消注册我的接收器类： “android.net.wifi.STATE_CHANGE” 如果我在清单中这样做，这非常有效。但这使它变得静止。我想在activity类中动态地完成它。它在活动类中的通讯命令是什么？

这就是我的代码...... 而且由于注册和取消注册（多次）我的接收者（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类用于注册并向流程中的本地对象发送Intents广播。这会更快，更安全，因为您的活动不会离开您的应用程序。

以下示例显示了一个注册名为my-event的客户事件的活动。

@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);
}

Answer 2

使用以下方法注册/取消注册您的接收者：

registerReceiver(BroadcastReceiver receiver, new IntentFilter("android.net.wifi.STATE_CHANGE"));
unregisterReceiver(BroadcastReceiver receiver);

供参考，请查看this

Answer 3

不要在广播文件的onReceive中添加动态广播接收器。将其添加到应用程序的第一个活动或主要活动。如果您只在应用程序打开时才需要它。但是如果你需要它总是收到响应，只是将它添加到清单文件

在主要活动上注册动态广播接收器

MyReceiver reciver;

@Override
protected void onResume() {
    super.onResume();
    IntentFilter intentFilter = new IntentFilter();
    intentFilter.addAction("android.net.wifi.WIFI_STATE_CHANGED");
    intentFilter.addAction("android.net.wifi.STATE_CHANGE");
    reciver = new MyReceiver();
    registerReceiver(reciver, intentFilter);
}

在活动停止或关闭时取消注册广播接收器

@Override
protected void onStop() {
    super.onStop();
    unregisterReceiver(reciver);
}

Answer 4

也许我有点太晚了，但问题在于您在receiver = null方法中设置了onPause，然后再也没有设置它。您也尝试在onResume方法中注册它，但前提是null，这也没有意义。

您应该更改设置/测试接收器null值的逻辑，而只需使用boolean变量来跟踪接收器状态（如果已注册）或不）。

Answer 5

public void registerBroadcastReceiver(View view) {

    this.registerReceiver(broadCastReceiver, new IntentFilter(
        "android.intent.action.TIME_TICK"));
}


public void unregisterBroadcastReceiver(View view) {

    this.unregisterReceiver(broadCastReceiver);
}

在android中动态注册/取消注册广播接收器

5 个答案:

在主要活动上注册动态广播接收器

在活动停止或关闭时取消注册广播接收器