android四大组件——广播

Posted 2021-10-25 我不在学习在干什么

一、监听电量变化的广播

第一步：创建一个广播接收者，继承自BroadcastReceiver

private class BatteryLevelReceiver extends BroadcastReceiver{
    @Override
    public void onReceive(Context context, Intent intent){
    String action = intent.getAction();
    Log.d(TAG,"收到了电量变化"+action);
    }
}

动态注册

第二步：设置收听频道 

IntentFilter intentFilter = new IntentFilter();

第三步：设置频道

例：收听电量变化

intentFilter.addAction(Intent.ACTION_BATTERY_CHANGED);

第四步：创建广播接收者 

BatteryLevelReceiver batteryLevelReceiver  = new BatteryLevelReceiver();

第五步：注册广播

this.registerReceiver(batteryLevelReceiver,intentFilter);

取消注册：

protected void onDestroy() {
//防止内存泄漏
    super.onDestroy();
    if(batteryLevelReceiver!=null){
        this.unregisterReceiver(batteryLevelReceiver);
    }
}

静态注册

第一步：创建一个类，继承自BroadcastReceiver

public class BootCompleteReceiver extends BroadcastReceiver{略}

第二步：与动态设置action一样

<receiver android:name=".BootCompleteReceiver">
    <intent-filter>
       <action android:name="android.intent.action.BOOT_COMPLETED"></action>
    </intent-filter>
</receiver>