Android 第三次作业

Android第三次作业

制作一个音乐播放器：

1. 实现的功能

   • 实现播放，暂停，播放上一首，下一首功能
   • 音乐列表的显示

2. 页面截图

           

        

3.核心代码：

（1）界面：

 activity_main.xml:界面由

在<LinearLayout>线性布局当中嵌套一个<LinearLayout>：

 <LinearLayout>

    <TextView> ——获取本地音乐列表

    <ListView>——列表

    <LinearLayout>

        <Button>  ——上一首

        <Button>  ——暂停

        <Button>  ——播放

        <Button>  ——停止

        <Button>  ——下一首

    </LinearLayout>

</LinearLayout>

musiclist.xml:

用于显示歌曲列表，用线性布局：

<LinearLayout  android:orientation="vertical">

<ImageView> ——歌手照片

    <TextView/> ——歌曲名称

    <TextView/> ——演唱者

</LinearLayout>

（2）功能实现的核心代码：

c.MusicInfo核心代码：

public class MusicInfo {
    private String name;   //歌曲名称
    private String artical;  //歌手
    private int imageId;

    public MusicInfo(String name,String artical ,int imageId){
        this.artical=artical;
        this.name=name;
        this.imageId=imageId;
    }
    public String getName(){
        return name;
    }

    public String getArtical(){
        return artical;
    }

    public int getImageId(){
        return imageId;
    }
}

 

b. 自定义的音乐适配器MusicAdapter的核心代码：

public class MusicAdapter extends ArrayAdapter {
    private final int resourceId;
    public MusicAdapter(Context context, int textViewResourceId, List<MusicInfo> objects) {
        super(context, textViewResourceId, objects);

        this.resourceId =textViewResourceId;
    }
    public View getView(int position, View convertView, ViewGroup parent) {
        MusicInfo musicinfo = (MusicInfo) getItem(position);
        View view = LayoutInflater.from(getContext()).inflate(resourceId, null);//实例化一个对象
        ImageView  Image = (ImageView) view.findViewById(R.id.image);//获取该布局内的图片视图
        TextView  Name = (TextView) view.findViewById(R.id.name);//获取该布局内的歌曲名称文本视图
        TextView Artical = (TextView) view.findViewById(R.id.artical);//获取该布局内的歌手文本视图
        Image.setImageResource(musicinfo.getImageId());//为图片视图设置图片资源
        Name.setText(musicinfo.getName());//为文本视图设置文本内容
        Artical.setText(musicinfo.getArtical());//为文本视图设置文本内容
        return view;
    }

}

c. MainActivity核心代码：

  

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private List<MusicInfo>musiclist=new ArrayList<>();
    private MediaPlayer  mediaPlayer=new  MediaPlayer();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initMusicList();
        Button play=(Button)findViewById(R.id.btn_play);//播放
        Button stop=(Button)findViewById(R.id.btn_stop);//停止
        Button next=(Button)findViewById(R.id.btn_next);//下一曲
        Button up=(Button)findViewById(R.id.btn_up);//上一曲

        if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
            ActivityCompat.requestPermissions(MainActivity.this, new String[]{
                    Manifest.permission.WRITE_EXTERNAL_STORAGE}, 1);
        }else{
            initMediaPlay();
        }

       MusicAdapter adapter = new MusicAdapter(MainActivity.this, R.layout.musiclist, musiclist);
        ListView listView = (ListView) findViewById(R.id.listview);
        listView.setAdapter(adapter);
    }

    private void initMusicList(){
        MusicInfo music = new MusicInfo("明智之举","许嵩" ,R.drawable.xusong);
        musiclist.add(music);
        MusicInfo music1 = new MusicInfo("大千世界","许嵩", R.drawable.xosong1);
        musiclist.add(music1);
        MusicInfo music2 = new MusicInfo("庐州月","许嵩", R.drawable.xusong2);
        musiclist.add(music2);
        MusicInfo music3 = new MusicInfo("我乐意","许嵩", R.drawable.xusong3);
        musiclist.add(music3);
        MusicInfo music4 = new MusicInfo("幻听","许嵩", R.drawable.xusong4);
        musiclist.add(music4);
        MusicInfo music5 = new MusicInfo("天后","薛之谦", R.drawable.xusong);
        musiclist.add(music5);

    }
    private void   initMediaPlay(){
        File file = new File(Environment.getExternalStorageDirectory(),".mp3");

    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
//        super.onRequestPermissionsResult(requestCode, permissions, grantResults);
        switch(requestCode){
            case 1:
                if (grantResults.length > 0 && grantResults [0] == PackageManager.PERMISSION_GRANTED){
                    initMediaPlay();
                }else {
                    Toast.makeText(this, "拒绝权限无法使用程序",Toast.LENGTH_SHORT).show();
                    finish();
                }
                break;
            default:
        }
    }
    @Override
    public void onClick(View v) {
        switch(v.getId()){
            case R.id.btn_play:
                if(!mediaPlayer.isPlaying()){
                    mediaPlayer.start();//播放
                }
                break;
            case R.id.btn_pause:
                if(mediaPlayer.isPlaying()){
                    mediaPlayer.pause();//暂停播放
                }
                break;
            case R.id.btn_stop:
                if(mediaPlayer.isPlaying()){
                    mediaPlayer.reset();//停止播放
                    initMediaPlay();
                }
                break;
            default:
                break;

        }
    }
    @Override
    protected void onDestroy() {
        super.onDestroy();
        if(mediaPlayer != null){
            mediaPlayer.stop();
            mediaPlayer.release();
        }
    }
}

codding地址：https://git.coding.net/tian-xin/Android_Music_Player.git