基于Android 开发的音乐播放器

package com.example.list_all_songs_from_storage; import androidx.appcompat.app.AppCompatActivity; import androidx.core.app.ActivityCompat; import androidx.core.content.ContextCompat; import android.Manifest; import android.content.ContentResolver; import android.content.Context; import android.content.Intent; import android.content.pm.PackageManager; import android.database.Cursor; import android.media.MediaPlayer; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.provider.MediaStore; import android.util.Log; import android.view.View; import android.widget.AdapterView; import android.widget.ArrayAdapter; import android.widget.ListView; import android.widget.Toast; import java.io.IOException; import java.lang.reflect.Array; import java.util.ArrayList; public class MainActivity extends AppCompatActivity { private static final int MY_PERMISSION_REQUEST = 1; MediaPlayer mp = new MediaPlayer(); Boolean musicIsPlaying = false; ArrayList<String> stringArrayList; // ArrayList<String> locationsArrayList; // ArrayList<String> arrayList; // String[] locationsArray; String locationsString = ""; String[] musicParts; ListView musicListView; ArrayAdapter<String> stringArrayAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE ) != PackageManager.PERMISSION_GRANTED) { if(ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE)) { ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, MY_PERMISSION_REQUEST); } else { ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE}, MY_PERMISSION_REQUEST); } } else { doStuff(); } } public void doStuff() { musicListView = (ListView) findViewById(R.id.musicListView); stringArrayList = new ArrayList<>(); getMusic(); stringArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, stringArrayList); musicListView.setAdapter(stringArrayAdapter); musicListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { @Override public void onItemClick(AdapterView<?> parent, View view, int position, long id) { // open music player to play desired song Log.i("debugparent", locationsString); // Log.i("debugparent", Integer.toString(position)); // Log.i("debugparent", String.valueOf(position)); // Log.i("debugparent", musicParts[(int) id]); // Log.i("debugparent", Array.toString(musicParts)); // for (String foo: musicParts) { // Log.i("debugs", foo); // } playMusic(position); } }); } private void playMusic(Integer position) { if(musicIsPlaying) { mp.pause(); mp.release(); } try { mp = new MediaPlayer(); // mp.setDataSource("/storage/emulated/0/Download/Lil Morty - Choppa on me.mp3"); mp.setDataSource(musicParts[position]); mp.prepare(); mp.start(); musicIsPlaying = true; } catch (IOException e) { e.printStackTrace(); } } public void getMusic() { ContentResolver contentResolver = getContentResolver(); Uri songUri = MediaStore.Audio.Media.EXTERNAL_CONTENT_URI; Cursor songCursor = contentResolver.query(songUri, null, null, null, null); if (songCursor != null && songCursor.moveToFirst()) { int songTitle = songCursor.getColumnIndex(MediaStore.Audio.Media.TITLE); int songArtist = songCursor.getColumnIndex(MediaStore.Audio.Media.ARTIST); int songLocation = songCursor.getColumnIndex(MediaStore.Audio.Media.DATA); int counter = 0; do { String currentTitle = songCursor.getString(songTitle); String currentArtist = songCursor.getString(songArtist); String currentLocation = songCursor.getString(songLocation); // locationsArrayList.add(currentLocation); stringArrayList.add(currentTitle + "\n" + currentArtist); locationsString += currentLocation; locationsString += "|"; // stringArrayList.add(currentLocation); // locationsArray[counter] = currentLocation; // Log.i("currentLocation", currentLocation.getClass().getName()); // if(currentLocation instanceof String) { // Log.i("Stringggggggggggggggg","messageeeeeeeeeeeeeeeeeeeeeee"); // arrayList.add(currentLocation); // } counter++; } while (songCursor.moveToNext()); musicParts = locationsString.split("\\|"); } } @Override public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) { switch (requestCode) { case MY_PERMISSION_REQUEST: { if(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) { if(ContextCompat.checkSelfPermission(MainActivity.this, Manifest.permission.READ_EXTERNAL_STORAGE) == PackageManager.PERMISSION_GRANTED) { Toast.makeText(this, "Permission granted!", Toast.LENGTH_SHORT).show(); doStuff(); } else { Toast.makeText(this, "No permission granted!", Toast.LENGTH_SHORT).show(); finish(); } return; } } } } }