可以将文章内容翻译成中文,广告屏蔽插件可能会导致该功能失效(如失效，请关闭广告屏蔽插件后再试):
问题:
I am currently trying to design a simple app that streams an internet radio station. I have the URL for the station and am setting up the Media Player like
MediaPlayer mediaPlayer = new MediaPlayer(); try { mediaPlayer.setDataSource(URL); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } catch (IllegalStateException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } try { mediaPlayer.prepare(); } catch (IllegalStateException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } mediaPlayer.start();
The program isn't crashing when emulated, but nothing is playing and I am get the following error:
start called in state 0
and right below it is
Error (-38,0)
Does anyone know what this means?
I've read a little about these state errors, but couldn't find anything that applies to my project.
回答1:
You need to call mediaPlayer.start() in the onPrepared method by using a listener. You are getting this error because you are calling mediaPlayer.start() before it has reached the prepared state.
Here is how you can do it :
mp.setDataSource(url); mp.setOnPreparedListener(this); mp.prepareAsync(); public void onPrepared(MediaPlayer player) { player.start(); }
回答2:
It seems like Error -38 means a state-exception (as the error-message indicates). For example if you call start(), before the song was ready, or when you call pause(), even if the song isn't playing at all.
To fix this issue check the state of the mediaPlayer before calling the methods. For example:
if(mediaPlayer.isPlaying()) { mediaPlayer.pause(); }
Additionally, the MediaPlayer is sending event-messages. Even if you do not need the prepared-event (although it would be a good idea to not start the playback before this event was fired) you must set a callback-listener. This also holds true for the OnErrorListener, OnCompletionListener, OnPreparedListener and OnSeekCompletedListener (if you call the seek method).
Listeners can be attached simply by
mediaPlayer.setOnPreparedListener(new OnPreparedListener() { @Override public void onPrepared(MediaPlayer mp) { // Do something. For example: playButton.setEnabled(true); } });
回答3:
I got this error when I was trying to get the current position (MediaPlayer.getCurrentPosition()) of media player when it wasn't in the prepared stated. I got around this by Keeping track of its state and only calling the getCurrentPosition() method after onPreparedListener is called.
回答4:
This is my code,tested and working fine:
package com.example.com.mak.mediaplayer; import android.media.MediaPlayer; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.app.Activity; public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); final MediaPlayer mpp = MediaPlayer.create(this, R.raw.red); //mp3 file in res/raw folder Button btnplay = (Button) findViewById(R.id.btnplay); //Play btnplay.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View vone) { mpp.start(); } }); Button btnpause = (Button) findViewById(R.id.btnpause); //Pause btnpause.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View vtwo) { if (mpp.isPlaying()) { mpp.pause(); mpp.seekTo(0); } } }); } }
回答5:
Some times file are encoded in a way that Android can't decode. Even some mp4 files can not be played. Please try a different file format (.3gp are played most of the time) and see..
回答6:
i tested below code. working fine
public class test extends Activity implements OnErrorListener, OnPreparedListener { private MediaPlayer player; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); player = new MediaPlayer(); player.setAudioStreamType(AudioManager.STREAM_MUSIC); try { player.setDataSource("http://www.hubharp.com/web_sound/BachGavotte.mp3"); player.setOnErrorListener(this); player.setOnPreparedListener(this); player.prepareAsync(); } catch (IllegalArgumentException e) { e.printStackTrace(); } catch (IllegalStateException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } @Override public void onDestroy() { super.onDestroy(); player.release(); player = null; } @Override public void onPrepared(MediaPlayer play) { play.start(); } @Override public boolean onError(MediaPlayer arg0, int arg1, int arg2) { return false; } }
回答7:
I encountered the same issue few days ago. My audio MediaPlayer works fine on devices with high processing power, but for slow devices, the media player just did not play some time and from LogCat it had many complain about called in wrong state. So I resolved it by calling putting the call to start(), pause(),... in onPrepared() method of OnPreparedListener() as below:
mediaPlayer.prepare(); mediaPlayer.setOnPreparedListener(new OnPreparedListener() { @Override public void onPrepared(MediaPlayer mp) { ........ mediaPlayer.start(); .... songControlBtn.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { if (mediaPlayer.isPlaying()) { mediaPlayer.pause(); } else { mediaPlayer.start(); } } }); mediaPlayer.setOnCompletionListener(new OnCompletionListener() { @Override public void onCompletion(MediaPlayer mp) { ............ } }); } });
Also try to release any media player that you do not need any more. For example, if you do not want to play the audio or video on background then you should call mediaPlayer.release() in onPause().
回答8:
I solved both the errors (-19,0) and (-38,0) , by creating a new object of MediaPlayer every time before playing and releasing it after that.
Before :
void play(int resourceID) { if (getActivity() != null) { //Using the same object - Problem persists player = MediaPlayer.create(getActivity(), resourceID); player.setAudioStreamType(AudioManager.STREAM_MUSIC); player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() { @Override public void onCompletion(MediaPlayer mp) { player.release(); } }); player.setOnPreparedListener(new MediaPlayer.OnPreparedListener() { @Override public void onPrepared(MediaPlayer mp) { mp.start(); } }); }
}
After:
void play(int resourceID) { if (getActivity() != null) { //Problem Solved //Creating new MediaPlayer object every time and releasing it after completion final MediaPlayer player = MediaPlayer.create(getActivity(), resourceID); player.setAudioStreamType(AudioManager.STREAM_MUSIC); player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() { @Override public void onCompletion(MediaPlayer mp) { player.release(); } }); player.setOnPreparedListener(new MediaPlayer.OnPreparedListener() { @Override public void onPrepared(MediaPlayer mp) { mp.start(); } }); }
}
回答9:
You get this message in the logs, because you do something that is not allowed in the current state of your MediaPlayer instance.
Therefore you should always register an error handler to catch those things (as @tidbeck suggested).
At first, I advice you to take a look at the documentation for the MediaPlayer class and get an understanding of what that with states means. See: http://developer.android.com/reference/android/media/MediaPlayer.html#StateDiagram
Your mistake here could well be one of the common ones, the others wrote here, but in general, I would take a look at the documentation of what methods are valid to call in what state: http://developer.android.com/reference/android/media/MediaPlayer.html#Valid_and_Invalid_States
In my example it was the method mediaPlayer.CurrentPosition, that I called while the media player was in a state, where it was not allowed to call this property.
回答10:
I also got this error i tried with onPreparedListener but still got this error. Finally i got the solution that error is my fault because i forgot the internet permission in Android Manifest xml. :)
I used sample coding for mediaplayer. I used in StreamService.java
onCreate method
String url = "http://s17.myradiostream.com:11474/"; mediaPlayer = new MediaPlayer(); mediaPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC); mediaPlayer.setDataSource(url); mediaPlayer.prepare();
回答11:
if(length>0) { mediaPlayer = new MediaPlayer(); Log.d("length",""+length); try { mediaPlayer.setDataSource(getApplication(),Uri.parse(uri)); } catch(IOException e) { e.printStackTrace(); } mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() { @Override public void onPrepared(MediaPlayer mediaPlayer) { mediaPlayer.seekTo(length); mediaPlayer.start(); } }); mediaPlayer.prepareAsync();
回答12:
It was every much frustrated. So, I got solution which works for me.
try { if (mediaPlayer != null) { mediaPlayer.release(); mediaPlayer = null; } mediaPlayer = new MediaPlayer(); mediaPlayer.setDataSource(file.getAbsolutePath()); mediaPlayer.setAudioStreamType(AudioManager.STREAM_NOTIFICATION); mediaPlayer.setOnPreparedListener(new MediaPlayer.OnPreparedListener() { @Override public void onPrepared(MediaPlayer mediaPlayer) { mediaPlayer.start(); mediaPlayer.setOnCompletionListener(new MediaPlayer.OnCompletionListener() { @Override public void onCompletion(MediaPlayer mediaPlayer) { mediaPlayer.stop(); mediaPlayer.release(); mediaPlayer = null; } }); } }); mediaPlayer.prepare(); } catch (Exception e) { e.printStackTrace(); }
回答13:
For me this worked
mp.seekTo(0); mp.start();
回答14:
I met the same problem just before,the friend at the first floor was right,you called the start() at the wrong time,you should set a listener for prepare() or prepareSync() with this method mediaPlayer.setOnPreparedListener(this); before prepare,in this callback call start().It may resolve your problem. I have tried already.
回答15:
mp = new MediaPlayer(); AssetFileDescriptor afd = mContext.getAssets().openFd(fileName); mp.reset(); mp.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength()); mp.prepare(); mp.setOnPreparedListener(new MediaPlayer.OnPreparedListener() { public void onPrepared(MediaPlayer mp) { mp.start(); } }); mp.prepareAsync();
翻译