Android studio 开发一个音乐播放器 详细代码

很抱歉，由于篇幅限制，无法在此处提供完整的代码。但我可以为您提供一些核心代码片段和步骤： 1. 首先，在 build.gradle 中添加以下依赖： ``` dependencies { implementation 'com.google.android.exoplayer:exoplayer:2.12.1' } ``` 2. 在您的布局文件中创建一个用户界面，包含播放/暂停按钮，歌曲名称、歌手和播放进度条。 ``` <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> <TextView android:id="@+id/song_title" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Song Title" /> <TextView android:id="@+id/song_artist" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="Song Artist" /> <SeekBar android:id="@+id/playback_seekbar" android:layout_width="match_parent" android:layout_height="wrap_content" /> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <ImageButton android:id="@+id/play_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/ic_play_arrow_black_24dp" /> <ImageButton android:id="@+id/pause_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:src="@drawable/ic_pause_black_24dp" /> </LinearLayout> </LinearLayout> ``` 3. 创建一个数据模型来存储歌曲的信息，例如歌曲名称、歌手、专辑、时长和文件路径。 ``` data class Song( val title: String, val artist: String, val album: String, val duration: Long, val uri: Uri ) ``` 4. 创建一个歌曲列表，并使用 RecyclerView 显示歌曲信息。 ``` class SongListAdapter( private val songs: List<Song>, private val onItemClick: (Song) -> Unit ) : RecyclerView.Adapter<SongListAdapter.ViewHolder>() { override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder { val view = LayoutInflater.from(parent.context) .inflate(R.layout.item_song, parent, false) return ViewHolder(view) } override fun onBindViewHolder(holder: ViewHolder, position: Int) { val song = songs[position] holder.titleTextView.text = song.title holder.artistTextView.text = song.artist holder.itemView.setOnClickListener { onItemClick(song) } } override fun getItemCount(): Int = songs.size class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) { val titleTextView: TextView = itemView.findViewById(R.id.song_title) val artistTextView: TextView = itemView.findViewById(R.id.song_artist) } } ``` 5. 创建一个音乐播放器服务，以便在后台播放音乐，并将其绑定到 Activity 中。 ``` class MusicService : Service() { private lateinit var exoPlayer: SimpleExoPlayer private var currentSong: Song? = null override fun onBind(intent: Intent): IBinder? = MusicBinder() inner class MusicBinder : Binder() { fun getService(): MusicService = this@MusicService } override fun onCreate() { super.onCreate() exoPlayer = SimpleExoPlayer.Builder(this).build() } override fun onDestroy() { super.onDestroy() exoPlayer.release() } fun play(song: Song) { if (song != currentSong) { currentSong = song val mediaItem = MediaItem.fromUri(song.uri) exoPlayer.setMediaItem(mediaItem) exoPlayer.prepare() } exoPlayer.play() } fun pause() { exoPlayer.pause() } fun seekTo(position: Long) { exoPlayer.seekTo(position) } fun getCurrentPosition(): Long = exoPlayer.currentPosition fun getDuration(): Long = exoPlayer.duration fun isPlaying(): Boolean = exoPlayer.isPlaying } ``` 6. 在音乐播放器服务中实现播放、暂停、跳转到下一首和上一首歌曲的功能。 ``` fun play(song: Song) { if (song != currentSong) { currentSong = song val mediaItem = MediaItem.fromUri(song.uri) exoPlayer.setMediaItem(mediaItem) exoPlayer.prepare() } exoPlayer.play() } fun pause() { exoPlayer.pause() } fun seekTo(position: Long) { exoPlayer.seekTo(position) } fun skipToNext() { val currentSongIndex = songs.indexOf(currentSong) val nextSongIndex = (currentSongIndex + 1) % songs.size val nextSong = songs[nextSongIndex] play(nextSong) } fun skipToPrevious() { val currentSongIndex = songs.indexOf(currentSong) val previousSongIndex = if (currentSongIndex == 0) { songs.size - 1 } else { currentSongIndex - 1 } val previousSong = songs[previousSongIndex] play(previousSong) } ``` 7. 在 Activity 中实现与音乐播放器服务的通信，以便更新用户界面和处理用户的输入。 ``` class MainActivity : AppCompatActivity() { private lateinit var binding: ActivityMainBinding private lateinit var musicService: MusicService private var isBound = false private val connection = object : ServiceConnection { override fun onServiceConnected(name: ComponentName?, service: IBinder?) { val binder = service as MusicService.MusicBinder musicService = binder.getService() isBound = true } override fun onServiceDisconnected(name: ComponentName?) { isBound = false } } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) binding = ActivityMainBinding.inflate(layoutInflater) setContentView(binding.root) val songList = listOf( Song("Song 1", "Artist 1", "Album 1", 180000, Uri.parse("path/to/song1.mp3")), Song("Song 2", "Artist 2", "Album 2", 240000, Uri.parse("path/to/song2.mp3")), Song("Song 3", "Artist 3", "Album 3", 300000, Uri.parse("path/to/song3.mp3")) ) val songListAdapter = SongListAdapter(songList) { song -> musicService.play(song) updateUI() } binding.songList.adapter = songListAdapter binding.playButton.setOnClickListener { musicService.play() updateUI() } binding.pauseButton.setOnClickListener { musicService.pause() updateUI() } binding.playbackSeekbar.setOnSeekBarChangeListener(object : SeekBar.OnSeekBarChangeListener { override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) { if (fromUser) { musicService.seekTo(progress.toLong()) } } override fun onStartTrackingTouch(seekBar: SeekBar?) {} override fun onStopTrackingTouch(seekBar: SeekBar?) {} }) } override fun onStart() { super.onStart() bindService(Intent(this, MusicService::class.java), connection, Context.BIND_AUTO_CREATE) } override fun onStop() { super.onStop() if (isBound) { unbindService(connection) isBound = false } } private fun updateUI() { binding.playButton.isEnabled = !musicService.isPlaying() binding.pauseButton.isEnabled = musicService.isPlaying() binding.playbackSeekbar.max = musicService.getDuration().toInt() binding.playbackSeekbar.progress = musicService.getCurrentPosition().toInt() } } ``` 以上是一个简单的步骤和代码示例，希望对您有所帮助！