如何在Android中恢复音频活动？
我已经实现了媒体播放器。 我只有一个活动。 当我开始活动时，我的音乐开始播放，当我按下后退按钮时，音乐片段处于暂停状态，当我恢复活动时，音乐会恢复正常。 但是在歌曲结束后我尝试恢复我的应用程序后出现错误。 应用程序崩溃了，我在back-press方法（ mp.pause(); ）中mp.pause(); IllegalStateExceptionexception。
请查看下面的代码，并建议我是否做错了什么。
public class Audio_Activity extends Activity { private MediaPlayer mp; Button btnStartStop ; int length; SharedPreferences prefs; ImageView imgVw; public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.audio); init(); imgVw.setImageResource(R.raw.teddy_two); prefs = PreferenceManager.getDefaultSharedPreferences(this); mp=MediaPlayer.create(Audio_Activity.this,R.raw.ennamo_yadho); Log.e("Song is playing","in Mediya Player "); Log.e("Current ","Position -> " + length); mp.setLooping(false); mp.start(); btnChapter.setEnabled(false); mp.setOnCompletionListener(new MediaPlayer.OnCompletionListener() { @Override public void onCompletion(MediaPlayer mp) { // TODO Auto-generated method stub mp.stop(); mp.release(); btnChapter.setEnabled(true); System.out.println("Music is over and Button is enable !!!!!!"); } }); } @Override public void onConfigurationChanged(Configuration newConfig) { super.onConfigurationChanged(newConfig); // Checks the orientation of the screen if (newConfig.orientation == Configuration.ORIENTATION_LANDSCAPE) { Toast.makeText(this, "landscape", Toast.LENGTH_SHORT).show(); } else if (newConfig.orientation == Configuration.ORIENTATION_PORTRAIT){ Toast.makeText(this, "portrait", Toast.LENGTH_SHORT).show(); } } @Override public void onPause() { super.onStop(); SharedPreferences. Editor prefsEdit = prefs.edit(); int position = mp.getCurrentPosition(); prefsEdit.putInt("mediaPosition", position); prefsEdit.commit(); } @Override protected void onResume() { super.onResume(); System.out.println("Activity is Resume !!!"); int position = prefs.getInt("mediaPosition", 0); mp.seekTo(position); } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { if ((keyCode == KeyEvent.KEYCODE_BACK)) { if(mp!= null) { f(mp.isPlaying()) { mp.pause(); } } finish(); return true; } return super.onKeyDown(keyCode, event); } }
这是我的Log Cat
07-09 11:52:01.057: I/System.out(6854): Music is over and Button is enable !!!!!! 07-09 11:52:03.297: D/AndroidRuntime(6854): Shutting down VM 07-09 11:52:03.297: W/dalvikvm(6854): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 07-09 11:52:03.339: E/AndroidRuntime(6854): FATAL EXCEPTION: main 07-09 11:52:03.339: E/AndroidRuntime(6854): java.lang.IllegalStateException 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.media.MediaPlayer.isPlaying(Native Method) 07-09 11:52:03.339: E/AndroidRuntime(6854): at com.audio_demo.Audio_Activity.onKeyDown(Audio_Activity.java:203) 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.view.KeyEvent.dispatch(KeyEvent.java:2609) 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.app.Activity.dispatchKeyEvent(Activity.java:2375) 07-09 11:52:03.339: E/AndroidRuntime(6854): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchKeyEvent(PhoneWindow.java:1847) 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.view.ViewRootImpl.deliverKeyEventPostIme(ViewRootImpl.java:3701) 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.view.ViewRootImpl.handleImeFinishedEvent(ViewRootImpl.java:3651) 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:2818) 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.os.Handler.dispatchMessage(Handler.java:99) 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.os.Looper.loop(Looper.java:137) 07-09 11:52:03.339: E/AndroidRuntime(6854): at android.app.ActivityThread.main(ActivityThread.java:5041) 07-09 11:52:03.339: E/AndroidRuntime(6854): at java.lang.reflect.Method.invokeNative(Native Method) 07-09 11:52:03.339: E/AndroidRuntime(6854): at java.lang.reflect.Method.invoke(Method.java:511) 07-09 11:52:03.339: E/AndroidRuntime(6854): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 07-09 11:52:03.339: E/AndroidRuntime(6854): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 07-09 11:52:03.339: E/AndroidRuntime(6854): at dalvik.system.NativeStart.main(Native Method) 07-09 11:52:28.787: I/Process(6854): Sending signal. PID: 6854 SIG: 9
我理解这个问题是关于onResume（）中的mp.seekTo（posiotion）或onPause（）方法中的mp.getCurrentPosition。 该exception可能是因为没有初始化媒体播放器。 根据听众的说法，当歌曲结束时，你让你的播放器停止并释放，并在onResume上线mp.seekTo（位置）引起该exception。 在OnCompletion（）方法和onResume和onpPause方法中删除mp.release（）行。 还有一件事你需要做。 在代码中使用布尔值来了解您的媒体播放器是否已完成播放。 如下所示更改您的onCreat：
public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.audio); init(); imgVw.setImageResource(R.raw.teddy_two); prefs = PreferenceManager.getDefaultSharedPreferences(this); mp=MediaPlayer.create(Audio_Activity.this,R.raw.ennamo_yadho); Log.e("Song is playing","in Mediya Player "); Log.e("Current ","Position -> " + length); mp.setLooping(false); mp.start(); prefsEdit.putInt("mediaplaying", true); prefsEdit.commit(); btnChapter.setEnabled(false); mp.setOnCompletionListener(new MediaPlayer.OnCompletionListener() { @Override public void onCompletion(MediaPlayer mp) { // TODO Auto-generated method stub mp.stop(); prefsEdit.putInt("mediaplaying", false); prefsEdit.commit(); btnChapter.setEnabled(true); System.out.println("Music is over and Button is enable !!!!!!"); } }); @Override public void onPause() { super.onStop(); SharedPreferences. Editor prefsEdit = prefs.edit(); boolean isPlaying=prefs.getBoolean("mediaplaying",false); if(isPlaying){ int position = mp.getCurrentPosition(); prefsEdit.putInt("mediaPosition", position); prefsEdit.commit(); } } @Override protected void onResume() { super.onResume(); System.out.println("Activity is Resume !!!"); boolean isPlaying=prefs.getBoolean("mediaplaying",false); if(isPlaying){ int position = prefs.getInt("mediaPosition", 0); mp.seekTo(position); } }