android - Nougat 上未调用 TelephonyManager 的 PhoneStateListener

Question

我制作了一个示例应用程序和 PhoneStateListener

TelephonyManager telephony = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE); //TelephonyManager object
    telephony.listen(new PhoneStateListener() {
        @Override
        public void onCallStateChanged(int state, String incomingNumber) {
            Log.i("brian", "call state = " + state + " incoming number " + incomingNumber);
            switch (state) {
                case TelephonyManager.CALL_STATE_IDLE:
                    break;
                case TelephonyManager.CALL_STATE_RINGING:

                    break;
                case TelephonyManager.CALL_STATE_OFFHOOK:

                    break;
            }
        }
    }, PhoneStateListener.LISTEN_CALL_STATE); //Register our listener with TelephonyManager

    Log.i("brian", "READ_PHONE_STATE = " + ContextCompat.checkSelfPermission(this,
            Manifest.permission.READ_PHONE_STATE));

按预期工作，但当我将上述代码添加到我的更大的应用程序时，onCallStateChanged 仅在最初订阅时调用。没有电话状态变化通知我。在这两个项目中，底部日志行“READ_PHONE_STATE =”始终被授予，我的目标是 sdk 22，所以我认为没有运行时权限。在我较大的应用程序中，我将代码粘贴到主要 Activity 和长期服务中，都没有获得状态更改事件。当我在 android < 7.0 上运行我的代码时，它们都可以工作，我不知道为什么。在警告或错误日志中看不到任何实质内容。

Answer 1

正如 Vairavan 在 this 中提到的那样回答，PhoneStateListener 的引用方式发生了内部变化:

Local reference to PhoneStateListener is kept track internally only by a weak reference. This makes it eligible for garbage collection upon function exit and once the listener is finalized, apps will not receive any further updates. Solution is to keep a reference to PhoneStateListener via class member variable.

参见:https://github.com/aosp-mirror/platform_frameworks_base/commit/f5d7c587e86c64e657a15a12ad70e75d47c48d99#diff-5af2ac899de823cf60597e554bf67fe0 .