广播被延迟 [英] Broadcasts are delayed

问题描述

我们使用广播来传达远程服务和UI之间的状态更改。这样做时，我们发现了一个非常奇怪的行为：有时（我找不到任何线索，为什么）这些广播会延迟8秒左右。

We use broadcasts to communicate state changes between a remote services and our UI. Doing this, we discovered a very strange behaviour: Sometimes (I can not find any clues why) these broadcasts are delayed around 8s.

我们如何发送它们（非常基本， mState 只是一个枚举）（服务中的远程过程）：

How we send them (pretty basic, mState is just a enum) (Remote process in service):

Intent intent = new Intent();
intent.setAction(ACTION_STATE_CHANGED);
intent.putExtra(EXTRA_STATE, mState);

Service.get().sendBroadcast(intent, null);

如何注册静态接收器（应用程序）：

How the static receiver is registered (App):

<receiver android:name=".ServiceStateReceiver">
    <intent-filter>
        <action android:name="service.intent.action.STATE_CHANGE" />
    </intent-filter>
</receiver>

接收器类别（应用程序）：

The receiver class (App):

public class ServiceStateReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        Log.v("State", "State via static received");
    }
}

现在有时会延迟（对于相同的州总是如此） ）

This is now sometimes delayed (always for the same states)

状态枚举：

public enum State {
    DISCONNECTED,
    BT_DISABLED,
    BT_SCANNING,
    BT_TIMEOUT,
    BT_FAILURE,
    BT_LOCATION_NEEDED,
    CONNECTING,
    ACTIVATION_FAILURE,
    VIN_NEEDED,
    CAR_MODEL_NEEDED,
    MILEAGE_NEEDED,
    READY,
    IGNITION_OFF,
    IGNITION_ON;

    @Override
    public String toString() {
        return name();
    }
}

现在出现了一个奇怪的部分：如果我注册动态接收器，我们总是在那里立即收到所有广播。静态的仍然有那么大的延迟。如果我通过 sendOrderedBroadcast 发送广播（静态和动态）都具有此延迟。

Now comes the strange part: If I register a dynamic receiver we always receive ALL broadcasts immediately there. The static one still has that huge delay. If I send the broadcast via sendOrderedBroadcast BOTH (static & dynamic) have this delay.

动态接收器：

registerReceiver(new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                Log.i("State", "State via dynamic received");
            }
        }, new IntentFilter(State.ACTION_STATE_CHANGED));

到目前为止我一直在尝试：

What I tried so far:

• 从主线程/工作线程发送广播（未更改）


• 使用权限属性播放（未更改）


• 连续发送广播多次（不更改任何内容，现在仅获得多个延迟的广播）

也：无输出从logcat似乎相关。在不同的设备（OnePlus 3 7.1.1，Z3 6.0.1，S7 Edge 7.1.1）上进行了尝试，它们都表现出相同的行为

Also: No output from logcat which seems related. Tried on different devices (OnePlus 3 7.1.1, Z3 6.0.1, S7 Edge 7.1.1), all show the same behaviour

我认为这可能与以下方面有关： Android网络状态更改检测需要时间

I think this may be related: Android network state change detection takes time

推荐答案

搜索了几个小时的答案后，我发现了？发布此后的解决方案。

After searching for a answer for hours, I found the? solution after posting this.

在意图上添加 FLAG_RECEIVER_FOREGROUND 标志似乎可以完全消除此延迟。仍然很高兴知道为什么会发生这种情况，并且如果这是一个很好的解决方案，或者我是否以此破坏了其他东西。

It seems like that adding the FLAG_RECEIVER_FOREGROUND flag to the intent completly removes this delay. Would be still nice to know why this happens and if this is a good "fix" or if I destroy something else with this.

这可以解决问题：

    intent.setFlags(FLAG_RECEIVER_FOREGROUND);

如果已设置，则在发送广播时允许接收方在
个前台优先级，超时间隔更短。在正常的
广播期间，不会自动将接收者悬挂在
背景优先级之外。

If set, when sending a broadcast the recipient is allowed to run at foreground priority, with a shorter timeout interval. During normal broadcasts the receivers are not automatically hoisted out of the background priority class.

资料来源：
https://developer.android.com/reference/android/ content / Intent.html＃FLAG_RECEIVER_FOREGROUND

这篇关于广播被延迟的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！