如何使用LocalBroadcastManager？

Question

LocalBroadcastManager如谷歌文档和服务广播文档中所述如何使用/定位？

我试图谷歌它,但没有可用的代码开始？

文件说如果我想在我的应用程序进程内部进行广播,我应该使用它,但我不知道在哪里寻找这个.

任何帮助/评论？

更新:我知道如何使用广播,但不知道如何LocalBroadcastManager在我的项目中使用.

Answer 1

无论如何我会回答这个问题.以防有人需要它.

ReceiverActivity.java

监视名为的事件的通知的活动"custom-event-name".

@Override
public void onCreate(Bundle savedInstanceState) {

  ...

  // Register to receive messages.
  // We are registering an observer (mMessageReceiver) to receive Intents
  // with actions named "custom-event-name".
  LocalBroadcastManager.getInstance(this).registerReceiver(mMessageReceiver,
      new IntentFilter("custom-event-name"));
}

// Our handler for received Intents. This will be called whenever an Intent
// with an action named "custom-event-name" is broadcasted.
private BroadcastReceiver mMessageReceiver = new BroadcastReceiver() {
  @Override
  public void onReceive(Context context, Intent intent) {
    // Get extra data included in the Intent
    String message = intent.getStringExtra("message");
    Log.d("receiver", "Got message: " + message);
  }
};

@Override
protected void onDestroy() {
  // Unregister since the activity is about to be closed.
  LocalBroadcastManager.getInstance(this).unregisterReceiver(mMessageReceiver);
  super.onDestroy();
}

SenderActivity.java

发送/广播通知的第二个活动.

@Override
public void onCreate(Bundle savedInstanceState) {

  ...

  // Every time a button is clicked, we want to broadcast a notification.
  findViewById(R.id.button_send).setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
      sendMessage();
    }
  });
}

// Send an Intent with an action named "custom-event-name". The Intent sent should 
// be received by the ReceiverActivity.
private void sendMessage() {
  Log.d("sender", "Broadcasting message");
  Intent intent = new Intent("custom-event-name");
  // You can also include some extra data.
  intent.putExtra("message", "This is my message!");
  LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}

使用上面的代码,每次R.id.button_send单击按钮时,都会广播一个Intent并由mMessageReceiverin 接收ReceiverActivity.

调试输出应如下所示:

01-16 10:35:42.413: D/sender(356): Broadcasting message
01-16 10:35:42.421: D/receiver(356): Got message: This is my message! 

Answer 2

我宁愿全面回答.

1. LocalbroadcastManager包含在android 3.0及更高版本中,所以你必须使用支持库v4进行早期版本.看这里的说明

2. 创建广播接收器:

   private BroadcastReceiver onNotice= new BroadcastReceiver() {
   
       @Override
       public void onReceive(Context context, Intent intent) {
           // intent can contain anydata
           Log.d("sohail","onReceive called");
           tv.setText("Broadcast received !");
   
       }
   };
   

3. 在onResume中注册您的接收器,例如:

   protected void onResume() {
           super.onResume();
   
           IntentFilter iff= new IntentFilter(MyIntentService.ACTION);
           LocalBroadcastManager.getInstance(this).registerReceiver(onNotice, iff);
       }
   
   //MyIntentService.ACTION is just a public static string defined in MyIntentService.
   

4. onPause中的unRegister接收器:

   protected void onPause() {
     super.onPause();
     LocalBroadcastManager.getInstance(this).unregisterReceiver(onNotice);
   }
   

5. 现在,每当从应用程序的活动或服务发送localbroadcast时,onReceive on onNotice将被调用:).

编辑:您可以在这里阅读完整的教程LocalBroadcastManager:Intra应用程序消息传递

Answer 3

在接收结束时:

• 首先注册LocalBroadcast Receiver

• 然后处理onReceive中的传入意图数据.

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
  
        LocalBroadcastManager lbm = LocalBroadcastManager.getInstance(this);
        lbm.registerReceiver(receiver, new IntentFilter("filter_string"));
    }
  
    public BroadcastReceiver receiver = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent != null) {
                String str = intent.getStringExtra("key");
                // get all your data from intent and do what you want 
            }
        }
    };
  

发送结束时:

   Intent intent = new Intent("filter_string");
   intent.putExtra("key", "My Data");
   // put your all data using put extra 

   LocalBroadcastManager.getInstance(this).sendBroadcast(intent);

Answer 4

在Eclipse中,最终我必须通过右键单击我的项目并选择以下内容来添加兼容性/支持库:

Android Tools - > Add Support Library

一旦添加,我就可以LocalBroadcastManager在我的代码中使用类.

Answer 5

如何将全局广播更改为LocalBroadcast

1)创建实例

LocalBroadcastManager localBroadcastManager = LocalBroadcastManager.getInstance(this);

2)用于注册BroadcastReceiver

更换

registerReceiver(new YourReceiver(),new IntentFilter("YourAction"));

同

localBroadcastManager.registerReceiver(new YourReceiver(),new IntentFilter("YourAction"));

3)用于发送广播消息

更换

sendBroadcast(intent);

同

localBroadcastManager.sendBroadcast(intent);

4)取消注册广播消息

更换

unregisterReceiver(mybroadcast);

同

localBroadcastManager.unregisterReceiver(mybroadcast);

Answer 6

androidx.localbroadcastmanager 在 1.1.0 版中已弃用

原因

LocalBroadcastManager是应用程序范围内的事件总线，在您的应用程序中包含违反层的行为；任何组件都可以侦听来自任何其他组件的事件。它继承了系统BroadcastManager的不必要用例限制；开发人员必须使用Intent，即使对象只存在于一个进程中，也永远不要离开它。出于同样的原因，它不遵循基于功能的BroadcastManager。

这些加在一起使开发人员感到困惑。

替代

您可以将的用法替换LocalBroadcastManager为可观察模式的其他实现。根据您的用例，合适的选项可能是LiveData反应流。

LiveData的优势

您可以LiveData使用单例模式扩展对象以包装系统服务，以便可以在您的应用程序中共享它们。该LiveData对象一次连接到系统服务，然后任何需要资源的观察者都可以监视该LiveData对象。

 public class MyFragment extends Fragment {
    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        LiveData<BigDecimal> myPriceListener = ...;
        myPriceListener.observe(this, price -> {
            // Update the UI.
        });
    }
}

该observe()方法将作为实例的片段LifecycleOwner作为第一个参数。这样做表示此观察者已绑定到Lifecycle与所有者关联的对象，这意味着：

• 如果Lifecycle对象未处于活动状态，则即使值更改也不会调用观察者。

• 生命周期对象销毁后，观察者将自动删除

LiveData对象具有生命周期感知这一事实意味着您可以在多个活动，片段和服务之间共享它们。

Answer 7

当您使用 LocalBroadcastReceiver 玩够了时，我建议您尝试一下Green Robot 的 EventBus - 与 LBR 相比，您一定会意识到它的不同之处和实用性。更少的代码，可定制接收者的线程（UI/Bg），检查接收者的可用性，粘性事件，事件可以用作数据传递等。

Answer 8

使用的 Kotlin 版本LocalBroadcastManager：

请检查以下代码registering和 sending消息。receivingbroadcast

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // register broadcast manager
        val localBroadcastManager = LocalBroadcastManager.getInstance(this)
        localBroadcastManager.registerReceiver(receiver, IntentFilter("your_action"))
    }

    // broadcast receiver
    var receiver: BroadcastReceiver = object : BroadcastReceiver() {
        override fun onReceive(context: Context?, intent: Intent?) {
            if (intent != null) {
                val str = intent.getStringExtra("key")
                
            }
        }
    }

    /**
     * Send broadcast method
     */
    fun sendBroadcast() {
        val intent = Intent("your_action")
        intent.putExtra("key", "Your data")
        LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
    }

    override fun onDestroy() {
        // Unregister broadcast
        LocalBroadcastManager.getInstance(this).unregisterReceiver(receiver)
        super.onDestroy()
    }

}