将音频从raw目录移至assets目录并保留进度保存功能

核心修改点 #

原代码依赖MediaPlayer.create()直接加载raw目录资源，改为从assets目录加载时，需要通过AssetManager获取音频文件输入流来初始化MediaPlayer，同时完整保留原有的SharedPreferences进度保存与恢复逻辑。

修改后的完整代码 #

// 补充类成员变量声明
private MediaPlayer mediaPlayer;
private SharedPreferences mPreferences;
private SharedPreferences.Editor editor;
private SeekBar seekBar;
private ImageButton playbttn, lastbuttn;
private boolean playing = true;
private int currentposition;
private Handler handler = new Handler();
private Runnable runnable;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main); // 按实际布局ID调整

    // 初始化控件
    seekBar = findViewById(R.id.seekBar);
    playbttn = findViewById(R.id.playbttn);
    lastbuttn = findViewById(R.id.lastbuttn);

    mPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    editor = mPreferences.edit();

    int mediaprogress = mPreferences.getInt("mediaprogress", 0);
    seekBar.setProgress(mediaprogress); // 直接恢复保存的进度

    seekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
            if (fromUser && mediaPlayer != null && mediaPlayer.isPrepared()) {
                seekBar.setProgress(progress);
                mediaPlayer.seekTo(progress);
                editor.putInt("mediaprogress", progress);
                editor.apply();
            }
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {}

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {}
    });

    lastbuttn.setOnClickListener(v -> handlePlayPause());
    playbttn.setOnClickListener(v -> handlePlayPause());
}

// 合并重复的播放暂停逻辑
private void handlePlayPause() {
    if (playing) {
        if (mediaPlayer == null) {
            try {
                initMediaPlayer();
                int savedProgress = mPreferences.getInt("mediaprogress", 0);
                mediaPlayer.seekTo(savedProgress);
                mediaPlayer.start();
                editor.putInt("mediaprogress", savedProgress);
                editor.apply();
            } catch (IOException e) {
                e.printStackTrace();
                Toast.makeText(getApplicationContext(), "音频加载失败", Toast.LENGTH_SHORT).show();
            }
        } else if (!mediaPlayer.isPlaying()) {
            mediaPlayer.seekTo(currentposition);
            mediaPlayer.start();
        }
        updateSeekBar();
        playbttn.setImageResource(R.drawable.ic_pause);
        playing = false;
    } else {
        if (mediaPlayer != null && mediaPlayer.isPlaying()) {
            mediaPlayer.pause();
            currentposition = mediaPlayer.getCurrentPosition();
            playbttn.setImageResource(R.drawable.ic_play);
            playing = true;
        }
    }
}

// 初始化Assets目录下的MediaPlayer
private void initMediaPlayer() throws IOException {
    mediaPlayer = new MediaPlayer();
    // 从assets目录获取音频文件描述符
    AssetFileDescriptor afd = getAssets().openFd("audio.mp3");
    mediaPlayer.setDataSource(afd.getFileDescriptor(), afd.getStartOffset(), afd.getLength());
    afd.close();
    mediaPlayer.prepare();
    // 音频播放完成后重置状态
    mediaPlayer.setOnCompletionListener(mp -> {
        playbttn.setImageResource(R.drawable.ic_play);
        playing = true;
        currentposition = 0;
        seekBar.setProgress(0);
        editor.putInt("mediaprogress", 0);
        editor.apply();
    });
}

public void updateSeekBar() {
    if (mediaPlayer != null && mediaPlayer.isPlaying()) {
        int current = mediaPlayer.getCurrentPosition();
        seekBar.setProgress(current);
        int duration = mediaPlayer.getDuration();
        seekBar.setMax(duration);

        editor.putInt("current", current);
        editor.putInt("duration", duration);
        editor.apply();
    }

    runnable = () -> updateSeekBar();
    handler.postDelayed(runnable, 1000);
}

@Override
protected void onStop() {
    super.onStop();
    if (mediaPlayer != null) {
        if (mediaPlayer.isPlaying()) {
            mediaPlayer.pause();
            currentposition = mediaPlayer.getCurrentPosition();
            editor.putInt("mediaprogress", currentposition);
            editor.apply();
        }
        playbttn.setImageResource(R.drawable.ic_play);
    }
    Toast.makeText(getApplicationContext(), "进度已保存", Toast.LENGTH_LONG).show();
}

@Override
protected void onDestroy() {
    super.onDestroy();
    // 释放MediaPlayer资源，避免内存泄漏
    if (mediaPlayer != null) {
        mediaPlayer.release();
        mediaPlayer = null;
    }
    handler.removeCallbacks(runnable);
}

关键改动说明 #

1. Assets资源加载：
   放弃MediaPlayer.create()，改用AssetManager.openFd()获取音频文件的文件描述符，通过setDataSource()设置给MediaPlayer，最后调用prepare()完成初始化，适配assets目录的资源读取逻辑。

2. 进度恢复优化：
   在MediaPlayer初始化并准备完成后，再调用seekTo()跳转到保存的进度，避免因MediaPlayer未就绪导致的状态错误；同时在onStop()中主动保存当前播放位置，确保进度不丢失。

3. 代码简化与稳定性：
   合并重复的播放暂停逻辑到handlePlayPause()方法，减少冗余；添加MediaPlayer资源释放逻辑（onDestroy()中），避免内存泄漏；增加异常捕获，处理音频加载失败的情况。

内容的提问来源于stack exchange，提问作者Nazzay