在BroadcastReceiver上使用newInstance時的InstantiationException

Question

我有一個帶有很多靜態便利方法的類。 其中之一應動態啟動BroadcastReceiver-但它始終返回InstantiationException。 BroadcastReceiver有一個無參數的構造函數，因此它應該可以工作-但事實並非如此。 這是我到目前為止所做的：

這是該類中的便捷方法：

// Static convenience methods in a tools class
public class MyTools {

    // Start BroadcastReceiver dynamically
    public static BroadcastReceiver startBroadcastReceiver(Context context,
            Class<? extends BroadcastReceiver> receiverClass, String receiverTag) {

        BroadcastReceiver receiver = null;

        try {
            receiver = (BroadcastReceiver) receiverClass.newInstance();
            if (receiver != null) {
                IntentFilter intentFilter = new IntentFilter(receiverTag);
                if (intentFilter != null) {
                    context.registerReceiver(receiver, intentFilter);
                }
            }
        } catch (Exception exception) {
            // --> InstantiationException
        }

        return receiver;
    }

    // ...
}

這是一個具有InnerClass BroadcastReceiver的活動，該活動嘗試使用此便捷方法啟動BroadcastReceiver：

// An activity with an InnerClass BroadcastReceiver
public class MyActivity extends Activity {

    public class MyBroadcastReceiver extends BroadcastReceiver {

        public static final String TAG = "aa.bb.cc.MyActivity.MyBroadcastReceiver";

        public static final long ACTION_UNDEFINED = 0;
        public static final long ACTION_DOSOMETHING = 1;

        @Override
        public void onReceive(Context context, Intent intent) {
            if (intent != null) {
                Bundle bundleExtras = intent.getExtras();
                if (bundleExtras != null) {
                    long action = bundleExtras.getLong("ACTION");
                    if (action == ACTION_DOSOMETHING) {
                        doSomething();
                    }
                }
            }
        }
    }

    private MyBroadcastReceiver receiver;

    @Override
    protected void onResume() {
        super.onResume();

        // Start BroadcastReceiver
        receiver = (MyBroadcastReceiver) MyTools.startBroadcastReceiver(this,
                MyBroadcastReceiver.class, MyBroadcastReceiver.TAG);
    }


    public void doSomething() {
        // ...
    }
}

這種方法有什么問題？

非常感謝您的幫助。

Answer 1

那就是問題所在

使您的廣播接收器成為靜態內部類公共靜態類MyBroadcastReceiver擴展了BroadcastReceiver

或在自己的文件中聲明

實例化異常中的無空構造函數消息可能會造成混淆