Android架构组件LiveData - 如何将broadcastReceivers绑定到生命周期

Question

使用 Android LiveData 我希望能够在 onInactive() 和 onActive() 回调中取消注册和注册许多 BroadcastReceivers。所以我想做这样的事情：

public class BroadcastRecieverLiveData extends LiveData<BroadCastReciever> {
    private BroadcastReciever reciever;
    private Context context;

    public BroadcastRecieverLiveData(Context context) {
        this.context = context;
    }

    @Override
    protected void onActive() {
        IntentFilter filter = new IntentFilter();
        filter.addAction("SOME_ACTION");
        filter.addAction("SOME_OTHER_ACTION");

        reciever = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                //do something based on the intent's action
            }
        };
        registerReceiver(reciever, filter);
    }

    @Override
    protected void onInactive() {
        if (reciever != null) {
            context.unregisterReceiver(reciever);
        }
    }
}

我在想这可能是一种清理代码而不是在onDestroy 上中继的设计模式。您对以这种方式使用 LiveData 有何看法？有一个使用的例子here

Answer 1

我认为对于接收者，你应该实现LifecycleObserver。 根据来自 Google codelab 的 LiveData 文档，

注意：在 ViewModel 中存储对 Context 或 View 的引用可以 导致内存泄漏。避免引用实例的字段 上下文或视图类。 onCleared() 方法对 取消订阅或清除对其他较长对象的引用 生命周期，但不适用于清除对 Context 或 View 对象的引用。

因此，您不应该在 LiveData 中进行上下文密集型操作。

相反，以下面的实现为例，

import android.arch.lifecycle.Lifecycle;
import android.arch.lifecycle.LifecycleObserver;
import android.arch.lifecycle.LifecycleOwner;
import android.arch.lifecycle.OnLifecycleEvent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;

public class ReceiverManager implements LifecycleObserver {

    private final Context mContext;
    private final MyBrodacastReceiver myBrodacastReceiver;

    public ReceiverManager(LifecycleOwner lifecycleOwner,
                           Context context) {
        mContext = context;
        myBrodacastReceiver = new MyBrodacastReceiver();
        lifecycleOwner.getLifecycle().addObserver(this);

    }

    @OnLifecycleEvent(Lifecycle.Event.ON_START)
    void registerYourReceiver() {
        mContext.registerReceiver(myBrodacastReceiver, new IntentFilter());
    }


    @OnLifecycleEvent(Lifecycle.Event.ON_STOP)
    void unRegisterYourReceiver() {
        mContext.unregisterReceiver(myBrodacastReceiver);
    }

    private static class MyBrodacastReceiver extends BroadcastReceiver {

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

        }
    }
}

谢谢。