Question

我正在创建一个应用程序，当任何音乐播放器播放音乐时启动并运行一个过程，并在音乐暂停时（或在通话期间）暂停该过程;我以为我可以使用FileObserver查看音乐文件何时被访问（它需要能够分辨出正在播放哪首歌曲），但每当我让观察者运行并启动音乐播放器时，一堆文件似乎立即访问。我的问题是：

是否有更好的方式（或任何方式）告诉任何播放器何时播放音乐？
如果启动另一首歌曲，如何停止FileObserver调用的方法的上一次迭代？
我如何＆＃34;暂停＆＃34;如果音乐暂停或音频焦点发生变化，该方法会运行吗？

我不确定我的观察者是否有问题，所以这就是：

    observer = new FileObserver(observedPath) {

        @Override
        public void onEvent(int event,final String file) {

            event &= FileObserver.ALL_EVENTS;
            switch(event) {
                case FileObserver.DELETE_SELF:
                    break;

                case FileObserver.OPEN:
                case FileObserver.ACCESS:

                    if(changesRunning > 0)
                    {
                        stopCurrentChange.post(new Runnable() {
                            @Override
                            public void run() {
                                return;
                            }
                        });
                    }
                    mainThreadHandler.post(new Runnable() {
                        @Override
                        public void run()
                        {
                            Log.v(TAG,"The event was triggered.");
                        }
                    });
                    handler.post(new Runnable() {

                        @Override
                        public void run() {
                            changesRunning++;//global variable being used
                            GatherChangeVolume(username, deviceName, file);
                            changesRunning = 0;
                        }
                });
                    break;
                default:
                    break;
            }

这是我的logcat输出：

08-10 17:30:19.874 3398-3398/badmexican333.volumizer17 V/TweakRunner: Service trying to watch /storage/sdcard1/Music/
08-10 17:30:34.309 3398-3398/badmexican333.volumizer17 V/TweakRunner: The event was triggered.
08-10 17:30:34.310 3398-3799/badmexican333.volumizer17 A/FileObserver: Unhandled exception in FileObserver badmexican333.volumizer17.TweakRunner$1@21c3ca00
                                                                   java.lang.NullPointerException
                                                                       at badmexican333.volumizer17.TweakRunner$1.onEvent(TweakRunner.java:123)
                                                                       at android.os.FileObserver$ObserverThread.onEvent(FileObserver.java:125)
                                                                       at android.os.FileObserver$ObserverThread.observe(Native Method)
                                                                       at android.os.FileObserver$ObserverThread.run(FileObserver.java:88)
08-10 17:30:34.314 3398-3799/badmexican333.volumizer17 A/FileObserver: Unhandled exception in FileObserver badmexican333.volumizer17.TweakRunner$1@21c3ca00
                                                                   java.lang.NullPointerException
                                                                       at badmexican333.volumizer17.TweakRunner$1.onEvent(TweakRunner.java:123)
                                                                       at android.os.FileObserver$ObserverThread.onEvent(FileObserver.java:125)
                                                                       at android.os.FileObserver$ObserverThread.observe(Native Method)
                                                                       at android.os.FileObserver$ObserverThread.run(FileObserver.java:88)
08-10 17:30:34.314 3398-3398/badmexican333.volumizer17 V/TweakRunner: The event was triggered.
08-10 17:30:34.318 3398-3398/badmexican333.volumizer17 V/TweakRunner: The event was triggered.
08-10 17:30:34.319 3398-3799/badmexican333.volumizer17 A/FileObserver: Unhandled exception in FileObserver badmexican333.volumizer17.TweakRunner$1@21c3ca00
                                                                   java.lang.NullPointerException
                                                                       at badmexican333.volumizer17.TweakRunner$1.onEvent(TweakRunner.java:123)
                                                                       at android.os.FileObserver$ObserverThread.onEvent(FileObserver.java:125)
                                                                       at android.os.FileObserver$ObserverThread.observe(Native Method)
                                                                       at android.os.FileObserver$ObserverThread.run(FileObserver.java:88)
08-10 17:30:34.425 3398-3398/badmexican333.volumizer17 V/TweakRunner: The event was triggered.
08-10 17:30:34.425 3398-3799/badmexican333.volumizer17 A/FileObserver: Unhandled exception in FileObserver badmexican333.volumizer17.TweakRunner$1@21c3ca00
                                                                   java.lang.NullPointerException
                                                                       at badmexican333.volumizer17.TweakRunner$1.onEvent(TweakRunner.java:123)
                                                                       at android.os.FileObserver$ObserverThread.onEvent(FileObserver.java:125)
                                                                       at android.os.FileObserver$ObserverThread.observe(Native Method)
                                                                       at android.os.FileObserver$ObserverThread.run(FileObserver.java:88)
08-10 17:30:34.480 3398-3799/badmexican333.volumizer17 A/FileObserver: Unhandled exception in FileObserver badmexican333.volumizer17.TweakRunner$1@21c3ca00
                                                                   java.lang.NullPointerException
                                                                       at badmexican333.volumizer17.TweakRunner$1.onEvent(TweakRunner.java:123)
                                                                       at android.os.FileObserver$ObserverThread.onEvent(FileObserver.java:125)
                                                                       at android.os.FileObserver$ObserverThread.observe(Native Method)
                                                                       at android.os.FileObserver$ObserverThread.run(FileObserver.java:88)
08-10 17:30:34.484 3398-3398/badmexican333.volumizer17 V/TweakRunner: The event was triggered.
08-10 17:30:34.571 3398-3398/badmexican333.volumizer17 V/TweakRunner: The event was triggered.

在停止之前，输出在此模式中持续一段时间。

我是Android开发的新手，非常感谢任何帮助。

Answer 1

您可以使用AudioManager API轻松检查当前是否播放音乐。

AudioManager audioManager = (AudioManager) context.getSystemService(Context.AUDIO_SERVICE);
if (audioManager.isMusicActive()) {
    // music is playing
}

请参阅：AudioManager.isMusicActive()

android如何判断音乐正在播放/暂停

1 个答案: