android第一行代码笔记9-Broadcast Receiv

• 标准广播(Normal broadcasts)是一种完全异步执行的广播

  
  企业微信截图_713ab319-484b-4c42-9ef3-50bdfc695188.png

• 有序广播(Ordered broadcasts)则是一种同步执行的广播，在广播发出之后，同一时刻 只会有一个广播接收器能够收到这条广播消息，当这个广播接收器中的逻辑执行完毕后，广 播才会继续传递。

  
  企业微信截图_1f28e1c9-fb33-4433-a9ba-ed8ccf032a3c.png

 public class MainActivity extends Activity {
        private IntentFilter intentFilter;
        private NetworkChangeReceiver networkChangeReceiver;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState); setContentView(R.layout.activity_main);
intentFilter = new IntentFilter(); intentFilter.addAction("android.net.conn.CONNECTIVITY_CHANGE"); networkChangeReceiver = new NetworkChangeReceiver(); registerReceiver(networkChangeReceiver, intentFilter);
}
        @Override
        protected void onDestroy() {
            super.onDestroy();
            unregisterReceiver(networkChangeReceiver);
        }
 class NetworkChangeReceiver extends BroadcastReceiver {
            @Override
            public void onReceive(Context context, Intent intent) {
                Toast.makeText(context, "network changes",
    Toast.LENGTH_SHORT).show();
} }
}