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我想在android中创建音乐播放器。这段代码是读取mp3文件的SD卡并在烤面包片中显示它们。Android中的Mp3 /音乐播放器
当我在手机上运行此应用程序时,手机会显示一个空白屏幕,即不显示歌曲。
import android.Manifest;
import android.content.pm.PackageManager;
import android.os.Environment;
import android.support.annotation.NonNull;
import android.support.v4.app.ActivityCompat;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.Toast;
import java.io.File;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
String items;
final int READ_EXTERNAL_STORAGE_REQUEST = 1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(this, new String[] {Manifest.permission.READ_EXTERNAL_STORAGE}, READ_EXTERNAL_STORAGE_REQUEST);
return;
}
ArrayList<File> mySongs = findSongs(Environment.getExternalStorageDirectory());
for(int i = 0; i < mySongs.size(); i++) {
toast(mySongs.get(i).getName().toString());
}
}
public ArrayList<File> findSongs(File root) {
ArrayList<File> al = new ArrayList<File>();
File[] files = root.listFiles();
for(File singleFile : files) {
if(singleFile.isDirectory() && !singleFile.isHidden()) {
al.addAll(findSongs(singleFile));
}
else {
if(singleFile.getName().endsWith(".mp3")) {
al.add(singleFile);
}
}
}
return al;
}
public void toast(String text) {
Toast.makeText(this, text, Toast.LENGTH_SHORT).show();
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch(requestCode) {
case READ_EXTERNAL_STORAGE_REQUEST: if(grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED){
return;
}
}
}
}
谢谢!除了我必须将权限请求从WRITE_EXTERNAL_STORAGE更改为READ_EXTERNAL_STORAGE以外,一切正常。感谢你的帮助。 –