我是Android开发新手，目前我正在开发android mediaplayer简单应用程序。所以，我的问题是为什么我得到这个例外。根据我的项目我定义了三个片段，第一个片段是播放器片段，它显示媒体播放器控制和播放歌曲，第二个片段是播放列表，其中包含歌曲列表，第三个片段是最近的播放列表，其中包含最近播放的歌曲。在此项目中，当我点击播放列表片段项目播放新歌并突然生成java.lang.IllegalStateException此例外。
这是我的播放器片段
package com.v1.sensoft.m_player.Fragment;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.audiofx.Visualizer;
import android.net.sip.SipSession;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.support.v4.view.MotionEventCompat;
import android.text.TextUtils;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageButton;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.Toast;
import com.v1.sensoft.m_player.Activity.AudioFxActivit;
import com.v1.sensoft.m_player.Adapter.SongAdapter;
import com.v1.sensoft.m_player.R;
import com.v1.sensoft.m_player.Utility.SongsManager;
import com.v1.sensoft.m_player.Utility.Utilities;
import com.v1.sensoft.m_player.Visualizer.SliderView;
import com.v1.sensoft.m_player.Visualizer.VisualizerView;
import com.v1.sensoft.m_player.djView.ClickWheel;
import com.v1.sensoft.m_player.djView.WheelModel;
import com.v1.sensoft.m_player.model.SongModel;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Random;
public class Player extends Fragment implements WheelModel.Listener,MediaPlayer.OnCompletionListener,SeekBar.OnSeekBarChangeListener {
private ImageButton btnPlay;
private ImageButton btnForward;
private ImageButton btnBackward;
private ImageButton btnNext;
private ImageButton btnPrevious;
private ImageButton btnRepeat;
private ImageButton btnShuffle;
private SeekBar songProgressBar;
private TextView songTitleLabel;
private TextView songCurrentDurationLabel;
private TextView songTotalDurationLabel;
// Media Player
public static MediaPlayer mp,mp2;
VisualizerView mVisualizerView;
SliderView sl;
private Visualizer mVisualizer;
// Handler to update UI timer, progress bar etc,.
private Handler mHandler = new Handler();;
private SongsManager songManager;
private Utilities utils;
private int seekForwardTime = 5000; // 5000 milliseconds
private int seekBackwardTime = 5000; // 5000 milliseconds
private int currentSongIndex = 0;
private boolean isShuffle = false;
private boolean isRepeat = false;
private ArrayList<SongModel> songsList = new ArrayList<SongModel>();
int songIndex;
SongAdapter songAdapter;
public Player(int position) {
songIndex = position;
}
public Player() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View android = inflater.inflate(R.layout.player, container, false);
ClickWheel wheel = (ClickWheel) android.findViewById(R.id.wheel);
wheel.getModel().addListener(this);
// variable initialization for button
btnPlay = (ImageButton) android.findViewById(R.id.btnPlay);
btnForward = (ImageButton) android.findViewById(R.id.btnForward);
btnBackward = (ImageButton) android.findViewById(R.id.btnBackward);
btnNext = (ImageButton) android.findViewById(R.id.btnNext);
btnPrevious = (ImageButton) android.findViewById(R.id.btnPrevious);
btnRepeat = (ImageButton) android.findViewById(R.id.btnRepeat);
btnShuffle = (ImageButton) android.findViewById(R.id.btnShuffle);
songProgressBar = (SeekBar) android.findViewById(R.id.songProgressBar);
songTitleLabel = (TextView) android.findViewById(R.id.songTitle);
songTitleLabel.setSelected(true);
songTitleLabel.setEllipsize(TextUtils.TruncateAt.MARQUEE);
songTitleLabel.setSingleLine(true);
songCurrentDurationLabel = (TextView)android.findViewById(R.id.songCurrentDurationLabel);
songTotalDurationLabel = (TextView) android.findViewById(R.id.songTotalDurationLabel);
// mVisualizerView = (VisualizerView) android.findViewById(R.id.myvisualizerview);
//audioManager = (AudioManager)getActivity().getSystemService(Context.AUDIO_SERVICE);
/* //sliding finger up and increase and decrease volume
android.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
int action = MotionEventCompat.getActionMasked(event);
if (action == MotionEvent.ACTION_MOVE) {
// put your volume change logic here, for example compare previously recorded x/y position to new one and change volume
audioManager.setStreamVolume(AudioManager.STREAM_MUSIC, 5, 0);
}
return true;
}
});*/
//Visualizer method
mp = new MediaPlayer();
// initAudio();
songManager = new SongsManager();
utils = new Utilities();
// Listeners
songProgressBar.setOnSeekBarChangeListener(this); // Important
mp.setOnCompletionListener(this); // Important
// Getting all songs list
songsList = songManager.getPlayList();
// By default play first song
if (songIndex==0)
{
playSong(0);
}
else
{
playSong(songIndex);
}
btnPlay.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// check for already playing
if (mp.isPlaying()) {
if (mp != null) {
mp.pause();
btnPlay.setImageResource(R.drawable.btn_play);
}
} else {
// Resume song
if (mp != null) {
mp.start();
btnPlay.setImageResource(R.drawable.btn_pause);
}
}
}
});
btnForward.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
int currentPosition = mp.getCurrentPosition();
if(currentPosition + seekForwardTime <= mp.getDuration()){
mp.seekTo(currentPosition + seekForwardTime);
}else{
mp.seekTo(mp.getDuration());
}
}
});
btnBackward.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
int currentPosition = mp.getCurrentPosition();
if(currentPosition - seekBackwardTime >= 0){
mp.seekTo(currentPosition - seekBackwardTime);
}else{
mp.seekTo(0);
}
}
});
btnNext.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
if(currentSongIndex < (songsList.size() - 1)){
playSong(currentSongIndex + 1);
currentSongIndex = currentSongIndex + 1;
}else{
playSong(0);
currentSongIndex = 0;
}
}
});
btnPrevious.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
if(currentSongIndex > 0){
playSong(currentSongIndex - 1);
currentSongIndex = currentSongIndex - 1;
}else{
playSong(songsList.size() - 1);
currentSongIndex = songsList.size() - 1;
}
}
});
btnRepeat.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
if(isRepeat){
isRepeat = false;
Toast.makeText(getActivity().getApplicationContext(), "Repeat is OFF", Toast.LENGTH_SHORT).show();
btnRepeat.setImageResource(R.drawable.btn_repeat);
}else{
isRepeat = true;
Toast.makeText(getActivity().getApplicationContext(), "Repeat is ON", Toast.LENGTH_SHORT).show();
isShuffle = false;
btnRepeat.setImageResource(R.drawable.btn_repeat_focused);
btnShuffle.setImageResource(R.drawable.btn_shuffle);
}
}
});
btnShuffle.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
if(isShuffle){
isShuffle = false;
Toast.makeText(getActivity().getApplicationContext(), "Shuffle is OFF", Toast.LENGTH_SHORT).show();
btnShuffle.setImageResource(R.drawable.btn_shuffle);
}else{
isShuffle= true;
Toast.makeText(getActivity().getApplicationContext(), "Shuffle is ON", Toast.LENGTH_SHORT).show();
isRepeat = false;
btnShuffle.setImageResource(R.drawable.btn_shuffle_focused);
btnRepeat.setImageResource(R.drawable.btn_repeat);
}
}
});
return android;
}
public void playSong(int songIndex){
try {
Log.e("playSong()...", "....is called");
mp.reset();
mp.setDataSource(songsList.get(songIndex).getSongPath());
mp.prepare();
songProgressBar.setProgress(0);
songProgressBar.setMax(100);
String songTitle = songsList.get(songIndex).getSongTitle();
songTitleLabel.setText(songTitle);
btnPlay.setImageResource(R.drawable.btn_pause);
updateProgressBar();
mp.start();
} catch (IllegalArgumentException e) {
e.printStackTrace();
} catch (IllegalStateException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
Log.i("song...songIndex...", "..." + songIndex);
mHandler.removeCallbacks(mUpdateTimeTask);
if(resultCode == 100){
currentSongIndex = data.getExtras().getInt("songIndex");
Log.i("song...currentSongIndex...", "..." + currentSongIndex);
// play selected song
playSong(currentSongIndex);
}
}
private Runnable mUpdateTimeTask = new Runnable() {
public void run() {
long totalDuration = mp.getDuration();
long currentDuration = mp.getCurrentPosition();
songTotalDurationLabel.setText(""+utils.milliSecondsToTimer(totalDuration));
songCurrentDurationLabel.setText(""+utils.milliSecondsToTimer(currentDuration));
int progress = (int)(utils.getProgressPercentage(currentDuration, totalDuration));
songProgressBar.setProgress(progress);
mHandler.postDelayed(this,100);
}
};
private void updateProgressBar() {
mHandler.postDelayed(mUpdateTimeTask,100);
}
@Override
public void onCompletion(MediaPlayer mp) {
if(isRepeat){
playSong(currentSongIndex);
} else if(isShuffle){
Random rand = new Random();
currentSongIndex = rand.nextInt((songsList.size() - 1) - 0 + 1) + 0;
playSong(currentSongIndex);
} else{
if(currentSongIndex < (songsList.size() - 1)){
playSong(currentSongIndex + 1);
currentSongIndex = currentSongIndex + 1;
}else{
playSong(0);
currentSongIndex = 0;
}
}
}
@Override
public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
}
@Override
public void onStartTrackingTouch(SeekBar seekBar) {
mHandler.removeCallbacks(mUpdateTimeTask);
}
@Override
public void onStopTrackingTouch(SeekBar seekBar) {
mHandler.removeCallbacks(mUpdateTimeTask);
int totalDuration = mp.getDuration();
int currentPosition = utils.progressToTimer(seekBar.getProgress(), totalDuration);
mp.seekTo(currentPosition);
updateProgressBar();
}
@Override
public void onDialPositionChanged(WheelModel sender, int nicksChanged) {
getActivity().setVolumeControlStream(AudioManager.STREAM_MUSIC);
mp2 =MediaPlayer.create(getActivity(),R.raw.djlazer);
mp2.start();
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (this.isVisible()) {
if (!isVisibleToUser) {
}
}
}
@Override
public void onDestroy() {
super.onDestroy();
mHandler.removeCallbacks(mUpdateTimeTask);
if(mp!=null)
{
if(mp.isPlaying()) mp.stop();
mp.reset();
mp.release();
}
}
}
播放列表片段。
public class Playlists extends ListFragment {
EditText edtSearch;
SongAdapter songAdapter;
ArrayList<SongModel> songList = new ArrayList<SongModel>();
SongsManager songsManager = new SongsManager();
// Songs list
public ArrayList<SongModel> songsList = new ArrayList<>();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View windows = inflater.inflate(R.layout.playlist, container, false);
return windows;
}
@Override
public void onViewCreated(View v, Bundle savedInstanceState) {
super.onViewCreated(v, savedInstanceState);
getListView().setFastScrollEnabled(true);
//ListView animation
LayoutAnimationController controller
= AnimationUtils.loadLayoutAnimation(
getActivity(), R.anim.list_layout_controller);
getListView().setLayoutAnimation(controller);
edtSearch = (EditText)getView().findViewById(R.id.search);
final ArrayList<SongModel> songsListData = songsManager.songList;
Log.i("songsListData...",""+songsListData.size());
SongsManager plm = new SongsManager();
// get all songs from sdcard
this.songsList = plm.getPlayList();
// looping through playlist
for (int i = 0; i < songsListData.size(); i++) {
// creating new HashMap
SongModel song = songsListData.get(i);
// adding HashList to ArrayList
songsListData.add(song);
}
songAdapter = new SongAdapter(getActivity(),songsList);
setListAdapter(songAdapter);
// selecting single ListView item
ListView lv = getListView();
// listening to single listitem click
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View arg0,
int position, long id) {
Log.i("Index", "..." + position);
songAdapter.setSelectedIndex(position);
Intent i = new Intent(getActivity().getApplicationContext(),Main.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK|Intent.FLAG_ACTIVITY_NEW_TASK);
SongModel songModel = (SongModel) songAdapter.getItem(position);
int indexOfSong = songAdapter.songsList.indexOf(songModel);
// Sending songIndex to PlayerActivity
i.putExtra("songIndex", indexOfSong);
startActivityForResult(i, 100);
//putting song in recentSongList arraylist
SongModel model = (SongModel) songAdapter.getItem(position);
model.setSongTitle(songModel.getSongTitle());
model.setSongPath(songModel.getSongPath());
Constant.recentSongList.add(model);
Log.i("recentSongList...","..."+Constant.recentSongList.size());
getActivity().finish();
}
});
lv.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
removeItemFromList(position);
return true;
}
private void removeItemFromList(int position) {
final int deletePosition = position;
AlertDialog.Builder alert = new AlertDialog.Builder(
getActivity());
alert.setTitle("Delete");
alert.setMessage("Do you want delete this song?");
alert.setPositiveButton("YES", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TOD O Auto-generated method stub
// main code on after clicking yes
songsList.remove(deletePosition);
songAdapter.notifyDataSetChanged();
songAdapter.notifyDataSetInvalidated();
}
});
alert.setNegativeButton("CANCEL", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
dialog.dismiss();
}
});
alert.show();
}
});
edtSearch.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence s, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence cs, int start, int before, int count) {
}
@Override
public void afterTextChanged(Editable s) {
String text = edtSearch.getText().toString().toLowerCase(Locale.getDefault());
songAdapter.filter(text);
}
});
}
@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
super.setUserVisibleHint(isVisibleToUser);
if (this.isVisible()) {
// If we are becoming invisible, then...
Log.d("setUserVisibleHint()...", "PlayList...Visible");
if (!isVisibleToUser) {
Log.d("setUserVisibleHint()...", "PlayList...notVisible");
// TODO stop audio playback
}
}
}
这是我的logcat
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: FATAL EXCEPTION: main
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: Process: com.v1.sensoft.m_player, PID: 17474
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: java.lang.IllegalStateException
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: at android.media.MediaPlayer.getDuration(Native Method)
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: at com.v1.sensoft.m_player.Fragment.Player$8.run(Player.java:289)
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: at android.os.Handler.handleCallback(Handler.java:808)
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: at android.os.Handler.dispatchMessage(Handler.java:103)
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: at android.os.Looper.loop(Looper.java:193)
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: at android.app.ActivityThread.main(ActivityThread.java:5333)
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: at java.lang.reflect.Method.invokeNative(Native Method)
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: at java.lang.reflect.Method.invoke(Method.java:515)
09-14 18:43:12.052 17474-17474/com.v1.sensoft.m_player E/AndroidRuntime: atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:824)
那么，我怎么能解决这个问题。如果有什么问题请帮帮忙。 提前感谢...
答案 0 :(得分：1)
根据the official document about MediaPlayer，MediaPlayer.getDuration()似乎是MediaPlayer.getDuration() MediaPlayer Idle ，Initialized或Error州。
当您使用MediaPlayer进行开发时，您应该好好照顾MediaPlayer的州。
答案 1 :(得分：0)
Android媒体播放器存在很多问题。 当媒体播放器处于空闲状态时，您无法调用方法。
Official Documents 像这样说。
此外，使用new创建的MediaPlayer对象处于空闲状态，而使用其中一个重载方便创建方法创建的对象不处于空闲状态。实际上，如果使用create方法创建成功，则对象处于Prepared状态。
使用
MediaPlayer mediaPlayer = MediaPlayer.create(this, Uri.parse("uriString"));
它已经调用了prepare（）方法，因此您可以开始自由使用它。 希望它能奏效。