Question

我在播放列表视图中的歌曲时遇到问题。

歌曲正确保存，但我不能播放它们。

我有一首歌的路径，所以一切都应该有用......

这是oncreate和outside的代码：

    listView = (ListView) findViewById(R.id.filesList);
    ArrayList<String> FilesInFolder = GetFiles("/sdcard/Kandydaci");

    listView.setAdapter(new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, FilesInFolder));

    listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> parent, View v, int position, long id) {
            MediaPlayer mediaPlayer = new MediaPlayer();
            try {
                File audioFile = getApplicationContext().getCacheDir();
                String name = (String) parent.getItemAtPosition(position);
                String OUTPUT_FILE ="sdcard/Kandydaci/"+name;
                mediaPlayer.setDataSource(OUTPUT_FILE);
                mediaPlayer.prepare();
                mediaPlayer.start();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    });

 public ArrayList<String> GetFiles(String DirectoryPath) {
    ArrayList<String> MyFiles = new ArrayList<String>();
    File f = new File(DirectoryPath);

    f.mkdirs();
    File[] files = f.listFiles();
    if (files.length == 0)
        return null;
    else {
        for (int i=0; i<files.length; i++)
            MyFiles.add(files[i].getName());
    }

    return MyFiles;
}

这是bug，我点击listview中的项目后得到：

E/ExtMediaPlayer-JNI: env->IsInstanceOf fails
E/MediaPlayer-JNI: JNIMediaPlayerFactory: bIsQCMediaPlayerPresent 0
E/ExtMediaPlayer-JNI: env->IsInstanceOf fails
E/MediaPlayer-JNI: JNIMediaPlayerFactory: bIsQCMediaPlayerPresent 0
E/FileSource: Failed to open file 'sdcard/Kandydaci/Thu Nov 30 17:36:34 GMT+01:00 2017.mp3'. (Permission denied)
E/GenericSource: Failed to create data source!
E/MediaPlayer: error (1, -2147483648)

Answer 1

您的代码绝对正确，但问题是您错过了定义访问EXTERNAL STORAGE的权限。

就这样。

在清单中声明：

   <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

现在在列表设置之前添加此代码：

If(ContextCompat.checkSelfPermission(MainActivity.this, permission) != PackageManager.PERMISSION_GRANTED) 
 { 
      // Should we show an explanation?
      if (ActivityCompat.shouldShowRequestPermissionRationale(MainActivity.this, permission)) 
      {
            //This is called if user has denied the permission before
            //In this case I am just asking the permission again 
           ActivityCompat.requestPermissions(MainActivity.this, new String[]{permission}, requestCode); 
     }
     else 
     { 
           ActivityCompat.requestPermissions(MainActivity.this, new String[]{permission}, requestCode);
     } 
 }
 else {
       Toast.makeText(this, "" + permission + " is already granted.", Toast.LENGTH_SHORT).show(); 

  }

通过此代码，您将获得存储访问权限，此处权限为：

   String ="Manifest.permission.WRITE_EXTERNAL_STORAGE";

快乐的编码!!

媒体播放器问题并在列表视图中播放歌曲

1 个答案: