[移动开发]Android 四大组件之Broadcast

发送广播

Intent intent = new Intent();
intent.putExtra("msg","hello,world!");
sendBroadcast(intent);

创建广播接收器

public class BatteryBroadcastReceiver extend BroadcastReceiver {
	private Activity activity;

    public DemoRecceiver(Activity activity) {
        this.activity = activity;
    }

    @Override
    public void onReceive(Context context, Intent intent) {
        int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0);
        // 在BroadReceiver中直接修改UI
        ((TextView)activity.findViewById(R.id.tv1)).setText("当前电量：" +  persent);
        Log.e("onReceive:", "当前电量:" + persent);
    }
}

注册广播接收器

静态注册（在AndroidManifest.xml中注册）

<receiver android:name=".DemoRecceiver"
	android:enabled="true"
	android:exported="true">
    <intent-filter>
    	<!--BATTERY_CHANGED这个广播在Android8.0之后不能静态注册-->
        <action android:name="android.intent.action.BATTERY_CHANGED"/>
    </intent-filter>
</receiver>

Android8.0（API26）之后某些广播不能静态注册详细参照隐式广播例外情况

动态注册

// 创建广播接收器实例
BatteryBroadcastReceiver receiver = new BatteryBroadcastReceiver(this);

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
	// 设置频道
	IntentFilter intentFilter = new IntentFilter();
	intentFilter.setAction(Intent.ACTION_EXTRA_BATTER);
	// 注册广播
	registerBroadcast(receiver,intentFilter);
}

注销广播接收器

@Override
protected void onDestroy() {
    super.onDestroy();
    // 注销广播
    unregisterReceiver(receiver);
}

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