(转)Android 中LocalBroadcastManager的使用方式

 

发表于2个月前(2014-11-03 22:05)   阅读（ 37） | 评论（0） 0人收藏此文章, 我要收藏

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1月10日 #长沙# OSC 源创会第32期开始报名

摘要 android中广播的作用非常大，对程序的运行起着非常重要的作用

LocalBroadcastManager

 

Android中BroadcastReceiver主要用途有

发送通知，更新UI或者数据，应用程序间相互通信，监听系统状态（比如开机，网络等）

Android中BroadcasetReceiver的注册方式

1. manifest清单文件中的全局注册

2. 按照生命周期，在Service或者Activity中使用代码注册

manifest的注册方式

 "com.sample.test.MyBroadcastReciever" >

                "com.sample.test.ACTION_DO_SOMETHING" >
                "android.intent.ACTION_WIFI_STATE_CHANGED" >

 

使用代码注册

SampleActivity

private   MyReceiver receiver;

@Override
public  void  onStart() {
      super .onStart();
    receiver =  new  MyReceiver();
    IntentFilter filter =  new  IntentFilter();
    filter.addAction( "android.intent.action.MY_BROADCAST" );
    registerReceiver(receiver, filter);
}
@Override
public  void  onStop(){
    super .onStop();
    unregisterReceiver(receiver);
}

 

Android中发送广播的方式

普通广播：无论优先级大小，将发送给所有监听Action="com.test.sample.action"的广播,内容不可被修改，无传递性。

Intent intent =  new  Intent(  "com.test.sample.action" );
sendBroadcast(intent);

 

异步（黏性）广播: 当处理完之后的Intent ，依然存在，这时候registerReceiver(BroadcastReceiver, IntentFilter) 还能收到他的值，直到你把它去掉 , 无传递性 , 无法终止(abort())广播。

发这个广播需要权限"android.permission.BROADCAST_STICKY" />

去掉是用这个方法removeStickyBroadcast(intent); 但别忘了在执行这个方法的应用里面 AndroidManifest.xml 同样要加上面的权限；

sendStickyOrderedBroadcast(intent, resultReceiver, scheduler,
       initialCode, initialData, initialExtras)

 

有序广播：

按照接收者的优先级顺序接收广播 , 优先级别在 intent-filter 中的 priority 中声明 ,-1000 到1000 之间 ，值越大 优先级越高 。可以终止广播意图的继续传播 ， 接收者可以篡改内容，具有传递性。

sendBroadcast(intent);

 

Android中的BroadcastReceiver可以用来发送信息到另一个广播，这种方式可实现程序或者进程间的通行。

 

上面回顾了一下Android的广播用例，总体来说安全性都不太好，因此只适用于安全性较低的数据传递，或者页面更新。

在android-support-v4.jar中引入了LocalBroadcastManager，称为局部通知管理器，这种通知的好处是安全性高，效率也高，适合局部通信，可以用来代替Handler更新UI

public  class  LocalServiceBroadcasterActivity  extends  Activity {
    static  final  String ACTION_STARTED =  "com.example.android.supportv4.STARTED" ;
    static  final  String ACTION_UPDATE =  "com.example.android.supportv4.UPDATE" ;
    static  final  String ACTION_STOPPED =  "com.example.android.supportv4.STOPPED" ;

    LocalBroadcastManager mLocalBroadcastManager;
    BroadcastReceiver mReceiver;

    @Override
    protected  void  onCreate(Bundle savedInstanceState) {
        super .onCreate(savedInstanceState);

        setContentView(R.layout.main);

        final  TextView callbackData = (TextView) findViewById(R.id.callback);
        callbackData.setText( "No broadcast received yet" );
        mLocalBroadcastManager = LocalBroadcastManager.getInstance( this );

        IntentFilter filter =  new  IntentFilter();
        filter.addAction(ACTION_STARTED);
        filter.addAction(ACTION_UPDATE);
        filter.addAction(ACTION_STOPPED);

        mReceiver =  new  BroadcastReceiver() {
            @Override
            public  void  onReceive(Context context, Intent intent) {
                if  (intent.getAction().equals(ACTION_STARTED)) {
                    callbackData.setText( "STARTED" );
                }  else  if  (intent.getAction().equals(ACTION_UPDATE)) {
                    callbackData.setText( "Got update: "  + intent.getIntExtra( "value" ,  0 ));
                }  else  if  (intent.getAction().equals(ACTION_STOPPED)) {
                    callbackData.setText( "STOPPED" );
                }
            }
        };
        mLocalBroadcastManager.registerReceiver(mReceiver, filter);


        Button button = (Button) findViewById(R.id.start);
        button.setOnClickListener(mStartListener);
        button = (Button) findViewById(R.id.stop);
        button.setOnClickListener(mStopListener);
    }

    @Override
    protected  void  onDestroy() {
        super .onDestroy();
        mLocalBroadcastManager.unregisterReceiver(mReceiver);
    }

    private  OnClickListener mStartListener =  new  OnClickListener() {
        public  void  onClick(View v) {
            startService( new  Intent(LocalServiceBroadcasterActivity. this , LocalService. class ));
        }
    };

    private  OnClickListener mStopListener =  new  OnClickListener() {
        public  void  onClick(View v) {
            stopService( new  Intent(LocalServiceBroadcasterActivity. this , LocalService. class ));
        }
    };

    public  static  class  LocalService  extends  Service {
        LocalBroadcastManager mLocalBroadcastManager;
        int  mCurUpdate;

        static  final  int  MSG_UPDATE =  1 ;

        Handler mHandler =  new  Handler() {
            @Override
            public  void  handleMessage(Message msg) {
                switch  (msg.what) {
                case  MSG_UPDATE: {
                    mCurUpdate++;
                    Intent intent =  new  Intent(ACTION_UPDATE);
                    intent.putExtra( "value" , mCurUpdate);
                    mLocalBroadcastManager.sendBroadcast(intent);
                    Message nmsg = mHandler.obtainMessage(MSG_UPDATE);
                    mHandler.sendMessageDelayed(nmsg,  1000 );
                }
                    break ;
                default :
                    super .handleMessage(msg);
                }
            }
        };

        @Override
        public  void  onCreate() {
            super .onCreate();
            mLocalBroadcastManager = LocalBroadcastManager.getInstance( this );
        }

        public  int  onStartCommand(Intent intent,  int  flags,  int  startId) {
            // Tell any local interested parties about the start.
            mLocalBroadcastManager.sendBroadcast( new  Intent(ACTION_STARTED));

            // Prepare to do update reports.
            mHandler.removeMessages(MSG_UPDATE);
            Message msg = mHandler.obtainMessage(MSG_UPDATE);
            mHandler.sendMessageDelayed(msg,  1000 );
            return  ServiceCompat.START_STICKY;
        }

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

            // Tell any local interested parties about the stop.
            mLocalBroadcastManager.sendBroadcast( new  Intent(ACTION_STOPPED));

            // Stop doing updates.
            mHandler.removeMessages(MSG_UPDATE);
        }

        @Override
        public  IBinder onBind(Intent intent) {
            return  null ;
        }
    }
}

 

 摘自：http://my.oschina.net/ososchina/blog/340339

转载于:https://www.cnblogs.com/antyi/p/4182970.html