BroadcastReceiver的使用--系统广播(显示手机电量）_安卓实验十一通过系统广播获取手机电量的变化

系统广播--以显示手机电量为例：

java文件：

当手机电量发生改变时，系统会对外发送Intent的Action，将action设为Intent.ACTION_BATTERY_CHANGED即可。

public class MainActivity extends AppCompatActivity {
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        //系统广播
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(Intent.ACTION_BATTERY_CHANGED);
        BatteryReceiver batteryReceiver = new BatteryReceiver();
        registerReceiver(batteryReceiver,intentFilter);
    }
}

BatteryReceiver里的内容:

public class BatteryReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Bundle bundle = intent.getExtras();
        int current = bundle.getInt("level");
        int total = bundle.getInt("scale");
 
        if(current * 1.0 / total ==1){
            Toast.makeText(context, "当前手机电量为"+(current / total)*100+"%", Toast.LENGTH_SHORT).show();
        }
    }
}

AndroidManifest需要申请权限：

 <uses-permission android:name="android.permission.BATTERY_STATS"
        tools:ignore="ProtectedPermissions" />

运行结果如下：