我想用前进，后退，播放，暂停按钮创建媒体播放器。从SoundCloud.com播放歌曲。这是我的代码..
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
b1 = (Button) findViewById(R.id.button);
b2 = (Button) findViewById(R.id.button2);
b3 = (Button) findViewById(R.id.button3);
b4 = (Button) findViewById(R.id.button4);
seekbar = (SeekBar) findViewById(R.id.seekBar);
mp = new MediaPlayer();
seekbar.setVisibility(SeekBar.VISIBLE);
seekbar.setProgress(0);
seekbar.setMax(mp.getDuration());
mp.setAudioStreamType(AudioManager.STREAM_MUSIC);
mp.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer player) {
mp.start();
}
});
b2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Toast.makeText(getApplicationContext(), "Playing sound", Toast.LENGTH_SHORT).show();
mp.start();
finalTime = mp.getDuration();
startTime = mp.getCurrentPosition();
if (oneTimeOnly == 0) {
seekbar.setMax((int) finalTime);
oneTimeOnly = 1;
}
seekbar.setProgress((int) startTime);
myHandler.postDelayed(UpdateSongTime, 100);
b2.setEnabled(true);
b3.setEnabled(false);
}
});
b3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (mp.isPlaying()) {
Toast.makeText(getApplicationContext(), "Pausing sound", Toast.LENGTH_SHORT).show();
mp.pause();
mp.seekTo(0);
}
b2.setEnabled(false);
b3.setEnabled(true);
}
});
b1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int temp = (int) startTime;
if ((temp + forwardTime) <= finalTime) {
startTime = startTime + forwardTime;
mp.seekTo((int) startTime);
Toast.makeText(getApplicationContext(), "You have Jumped forward 5 seconds", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getApplicationContext(), "Cannot jump forward 5 seconds", Toast.LENGTH_SHORT).show();
}
}
});
b4.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int temp = (int) startTime;
if ((temp - backwardTime) > 0) {
startTime = startTime - backwardTime;
mp.seekTo((int) startTime);
Toast.makeText(getApplicationContext(), "You have Jumped backward 5 seconds", Toast.LENGTH_SHORT).show();
} else {
Toast.makeText(getApplicationContext(), "Cannot jump backward 5 seconds", Toast.LENGTH_SHORT).show();
}
}
});
mListItems = new ArrayList<Track>();
final ListView listView = (ListView)findViewById(R.id.listview);
mAdapter = new SCTrackAdapter(this, mListItems);
listView.setAdapter(mAdapter);
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Track track = mListItems.get(position);
if (mp.isPlaying()) {
mp.stop();
mp.reset();
}
try {
mp.setDataSource(track.getStreamURL() + "?client_id=" + Config.CLIENT_ID);
mp.prepareAsync();
} catch (IOException e) {
e.printStackTrace();
}
}
});
SCService scService = SoundCloud.getService();
scService.getRecentTracks(new SimpleDateFormat("yyyy-MM-dd hh:mm:ss").format(new Date()), new Callback<List<Track>>() {
@Override
public void success(List<Track> tracks, Response response) {
loadTracks(tracks);
}
@Override
public void failure(RetrofitError error) {
Log.d(TAG, "Error: " + error);
}
});
}
private void loadTracks(List<Track> tracks) {
mListItems.clear();
mListItems.addAll(tracks);
mAdapter.notifyDataSetChanged();
}
private Runnable UpdateSongTime = new Runnable() {
public void run() {
startTime = mp.getCurrentPosition();
seekbar.setProgress((int)startTime);
myHandler.postDelayed(this, 100);
}
};
@Override
public void onDestroy() {
super.onDestroy();
mp.release();if (mp != null) {
if (mp.isPlaying()) {
mp.stop();
}
mp.release();
mp = null;
}
}
我还添加了AndroidMenifest。
<permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.INTERNET" />
<permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
我分别创建了Config，SCService，SCTrackAdapter，SounndCloude，Track ..我遵循这个站点的代码“http://www.sitepoint.com/develop-music-streaming-android-app”。 但我得到了错误。
01-07 14:59:46.055 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: Attempt to call getDuration without a valid mediaplayer
01-07 14:59:46.055 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: error (-38, 0)
01-07 14:59:46.276 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: Error (-38,0)
01-07 14:59:46.895 25541-25547/com.vetecstech.www.mediap E/MediaPlayer: error (1, -1004)
01-07 14:59:47.215 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: Error (1,-1004)
01-07 14:59:50.855 25541-25543/com.vetecstech.www.mediap D/dalvikvm: GC_CONCURRENT freed 1429K, 58% free 3082K/7175K, external 5368K/6641K, paused 4ms+4ms
01-07 14:59:53.035 25541-25546/com.vetecstech.www.mediap I/dalvikvm: Jit: resizing JitTable from 512 to 1024
当我点击列表项时，我收到了错误。错误在下面。
01-07 15:19:41.765 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: Error (1,-2147483648)
01-07 15:19:45.335 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: start called in state 0
01-07 15:19:45.335 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: error (-38, 0)
01-07 15:19:45.335 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: Attempt to call getDuration without a valid mediaplayer
01-07 15:19:45.335 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: error (-38, 0)
答案 0 :(得分：0)
mp = new MediaPlayer();
...
seekbar.setMax(mp.getDuration());
您正试图获取未准备好的MediaPlayer的持续时间，这会导致问题
01-07 14:59:46.055 25541-25541/com.vetecstech.www.mediap E/MediaPlayer: Attempt to call getDuration without a valid mediaplayer
您可能希望在OnPreparedListener
中移动seekbar.setMax(mp.getDuration());
mp.setOnPreparedListener(new MediaPlayer.OnPreparedListener() {
@Override
public void onPrepared(MediaPlayer player) {
seekbar.setMax(mp.getDuration());
mp.start();
}
});