【发布时间】：2016-08-10 22:39:51
【问题描述】：
我正在制作一个应用程序，该应用程序在任何音乐播放器播放音乐时启动并运行一个进程，并在音乐暂停时（或在通话期间）暂停该进程；我以为我可以只使用 FileObserver 来查看何时访问音乐文件（它需要能够判断正在播放哪首歌），但是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：
- 是否有更好的方法（或任何方法）来判断音乐何时从任何播放器播放？
- 如果开始播放另一首歌曲，我如何阻止 FileObserver 调用的方法的上一个迭代运行？
- 如果音乐暂停或音频焦点更改，我如何“暂停”正在运行的方法？
我不确定我的观察者是否有问题，所以这里是：
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，输出会以这种模式持续一段时间。
我是 android 开发的新手，非常感谢任何帮助。
【问题讨论】：
标签： android audio fileobserver