组件之BroadcastReceiver详解

一、BroadcastReceiver解析

（1）广播注册使用

public class MyBroadcastReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String name = intent.getStringExtra("name");
    }
}

（2）动态注册广播

public class MainActivity extends AppCompatActivity {

    private MyBroadcastReceiver myBroadcastReceiver;
    private IntentFilter intentFilter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        myBroadcastReceiver = new MyBroadcastReceiver();
        intentFilter = new IntentFilter();
        intentFilter.addAction("android.intent.action.MY_BROADCAST_RECEIVER");
        registerReceiver(myBroadcastReceiver, intentFilter);//注册广播
    }

    //发送广播
    private void sendOut(){
        Intent intent = new Intent("android.intent.action.MY_BROADCAST_RECEIVER");
        intent.putExtra("name","name");
        sendBroadcast(intent);
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        unregisterReceiver(myBroadcastReceiver);//注解广播
    }
}

（3）在配置文件中静态注册广播

<receiver android:name=".类名">
    <intent-filter>
        <action android:name="android.intent.action.MY_BROADCAST_RECEIVER"/>
    </intent-filter>
</receiver>

特点：动态注册广播接收器特点是当用来注册的Activity关掉后，广播也就失效了。静态注册无需担忧广播接收器是否被关闭，只要设备是开启状态，广播接收器也是打开着的

（4）其他广播

• 有序广播：将sendBroadcast改成sendOrderedBroadcast。priority接收广播的优先级
• 系统广播：
  屏幕被关闭：Intent.ACTION_SCREEN_OFF
  屏幕被打开：Intent.ACTION_SCREEN_ON
  系统启动完成：Intent.ACTION_BOOT_COMPLETED
  网络变化：android.net.conn.CONNECTIVITY_CHANGE
  充电时或电量发生变化：Intent.ACTION_BATTERY_CHANGED
• 本地广播：只有动态注册的广播才能使用，主要使用了一个LocalBroadcastManager来对广播进行管理，并提供了相应的发送广播和注册广播接收器的方法

LocalBroadcastManager localBroadcastManager = LocalBroadcastManager.getInstance(this);
//注册广播
localBroadcastManager.registerReceiver(myBroadcastReceiver,intentFilter);
//发送广播
localBroadcastManager.sendBroadcast(intent);
//反注册广播
localBroadcastManager.unregisterReceiver(myBroadcastReceiver);

• 粘性广播：.sendStickyBroadcast发送粘性广播，广播会一直滞留，当有匹配该广播的接收器被注册后，该接收器就会收到此条广播。sendStickyBroadcast只保留最后一条广播，并且一直保留。如果只想处理一遍该广播，可通过removeStickyBroadcast来实现。
  BroadcastReceiver源码解析