java - 在非 Activity 类中注册 BroadcastReceiver

Question

我必须在我必须在 Activity 中调用的类中使用 BroadcastReceiver。显然，我必须注册 BroadcastReceiver 然后我写了这段代码:

    public class MyClassName {

        Context context;
        BroadcastReceiver batteryInfoReceiverLevel;

        public void CheckBatteryLevel() {

        Log.d("App", "I'm in the CheckBatteryLevel");

        context.registerReceiver(batteryInfoReceiverLevel, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

        batteryInfoReceiverLevel = new BroadcastReceiver() {

            @Override
            public void onReceive(Context context, Intent intent) {

            Log.d("Apps", "I'm in the onReceive");

            int level= intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);

            if(level <=100) {
//Do something

            }

            else if(level >=100) {
//Do something
            }

            }

            };

        }

    }

当我运行代码时，应用程序崩溃给出“Error receiving broadcast Intent { act=android.intent.action.BATTERY_CHANGED flg=0x60000010 (has extras) } 并且崩溃行是

context.registerReceiver(batteryInfoReceiverLevel, new IntentFilter(Intent.ACTION_BATTERY_CHANGED));

我该如何解决？

Answer 1

这里有两个问题:

ρяσѕρєя K 指出了第一个:

通过向方法 CheckBatteryLevel() 或构造函数添加参数来初始化上下文我的类(class)

public class MyClass(Context ctx) {
    context = ctx;
}

其次，您必须在初始化 BroadcastReceiver 之后调用 registerReceiver(..)。否则将为空且未注册。

总而言之，应该这样做:

public class MyClassName {

    BroadcastReceiver batteryInfoReceiverLevel;

    public void CheckBatteryLevel(Context ctx) {

        Log.d("App", "I'm in the CheckBatteryLevel");

        batteryInfoReceiverLevel = new BroadcastReceiver() { // init your Receiver

            @Override
            public void onReceive(Context context, Intent intent) {

                Log.d("Apps", "I'm in the onReceive");
                int level= intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);
                if(level <=100) {
                    //Do something
                } else if(level >=100) {
                    //Do something
                }
            }
        };
        // register your Receiver after initialization 
        ctx.registerReceiver(batteryInfoReceiverLevel,
                  new IntentFilter(Intent.ACTION_BATTERY_CHANGED)); 
    }
}